David Grinspoon

David H. Grinspoon (born 1959) is an American astrobiologist. He is Senior Scientist at the Planetary Science Institute and was the former inaugural Baruch S. Blumberg NASA/Library of Congress Chair in Astrobiology for 2012-2013.
His research focuses on comparative planetology, with a focus on climate evolution on Earth-like planets and implications for habitability. He has also studied, written and lectured on the human influence on Earth, as seen in cosmic perspective.
He has published four books, "Venus Revealed", which was a finalist for the Los Angeles Times book prize, "Lonely Planets: The Natural Philosophy of Alien Life", which won the 2004 PEN literary award for nonfiction, "Earth in Human Hands", which was named one of NPR's Science Friday "Best Science Books of 2016" and "Chasing New Horizons: Inside the Epic First Mission to Pluto", co-authored with Alan Stern. He is adjunct professor of Astrophysical and Planetary Science at the University of Colorado.
Early life.
Grinspoon was born in 1959. His father was Harvard psychiatrist and author Lester Grinspoon. He holds degrees in Philosophy of Science and Planetary Science from Brown University and a doctorate in Planetary Sciences from the University of Arizona.
Career.
Grinspoon serves as an advisor to NASA on space exploration strategy and as an Interdisciplinary Scientist on the European Space Agency's Venus Express spacecraft mission to Venus. In addition to being a science team member of the NASA Astrobiology Institute Titan Team, he serves as science Co-Investigator and team lead for Education and Public Outreach for the Radiation Assessment Detector (RAD) on the Mars Science Laboratory.
His popular writing has appeared in numerous periodicals, such as Slate, Scientific American, Natural History, The Sciences, Seed, Astronomy, The Boston Globe, LA Times, and The New York Times. Grinspoon's technical papers have been published in Nature, Science, and numerous other journals. He has been featured on many television programs including PBS's Life Beyond Earth, BBC's The Planets, and History Channel's The Universe, as well as on NPR's Science Fridays, Wisconsin Public Radio, and BBC World Service shows. He has given invited talks at international conferences throughout the U.S., Europe, and Australia. Grinspoon also writes the bi-monthly "Cosmic Relief" column for Sky & Telescope magazine, where he is also a contributing editor. In addition, he has appeared several times as a guest, and also as guest host, of Neil deGrasse Tyson's popular podcast and live shows "StarTalk".
In 2013, he was invited to give the Carl Sagan Lecture at the Fall meeting of the American Geophysical Union.
Grinspoon currently serves as an adjunct professor at Georgetown University.
Awards.
Grinspoon has won many awards including the 2006 Carl Sagan Medal by the Division for Planetary Sciences of the American Astronomical Society for excellence in public communication of planetary science; Alpha Geek 2007 by WIRED Magazine; the 2004 PEN Center USA Literary Award for Research Nonfiction for "Lonely Planets"; 1997 Los Angeles Times Book Prize Finalist for "Venus Revealed"; and the 1989 Gerard P. Kuiper Memorial Award at the University of Arizona. Asteroid 22410 Grinspoon, a main-belt asteroid, is named after him.
Personal life.
Grinspoon is a musician who has played guitar and composed for many bands. Currently, he is performing with the House Band of the Universe. He lives in Washington, D.C. with his wife.


Neutrino mass hierarchy

 The problem of neutrino mass hierarchy is related to the fact that present experimental data on neutrino oscillations allow two possible classes of solutions.
In the first class, called Normal Hierarchy (NH) or Normal Ordering (NO), the two lightest mass eigenstates have a small mass difference, of the order of 10 meV, while the third eigenstate has a mass about 50 meV higher. In the Inverted Hierarchy (IH), also called Inverted Ordering (IO), the lightest mass eigenstate is followed by a doublet of higher mass eigenstates about 50 meV heavier, being again of about 10 meV the mass difference in the doublet. Present data slightly prefer the NO.


Ejnar Hertzsprung

Ejnar Hertzsprung (; 8 October 1873 – 21 October 1967) was a Danish chemist and astronomer born in Copenhagen. In the period 1911–1913, together with Henry Norris Russell, he developed the Hertzsprung–Russell diagram.
In 1913 he determined the distances to several Cepheid variable stars by parallax, and was thus able to calibrate the relationship, discovered by Henrietta Leavitt, between Cepheid period and luminosity. In this determination he made a mistake, possibly a slip of the pen, putting the stars 10 times too close. He used this relationship to estimate the distance to the Small Magellanic Cloud. From 1919 to 1946, Hertzsprung worked at Leiden Observatory in the Netherlands, from 1937 as director. Among his graduate students at Leiden was Gerard Kuiper.
Perhaps his greatest contribution to astronomy was the development of a classification system for stars to divide them by spectral type, stage in their development, and luminosity. He used the earlier classification system developed by Antonia Maury in his work. The so-called "Hertzsprung–Russell Diagram" has been used ever since as a classification system to explain stellar types and stellar evolution. He also discovered two asteroids, one of which is 1627 Ivar, an Amor asteroid.
His wife Henrietta (1881–1956) was a daughter of the Dutch astronomer Jacobus Kapteyn. Hertzsprung died in Roskilde in 1967. The asteroid 1693 Hertzsprung was named in his honour.


Walter Wislicenus

Walter Friedrich Wislicenus (November 5, 1859 – October 3, 1905) was a German astronomer. He taught at the University of Strasbourg starting in 1888, and was a professor from 1897 until his death. He was known for his lectures given outside of academia that attracted many non-scientists, and for his publications for the interested public.
Biography.
He was born in Halberstadt as the son of a preacher, and the nephew of Gustav Adolf Wislicenus, founder of the "free religious movement" in Germany.
After only one year of studies in Leipzig he decided to move to Strasbourg in 1880, where a new observatory was close to completion. In 1882 he joined an expedition to observe the transit of Venus at Bahía Blanca as an assistant. In 1883 he started to work for the Strasbourg Observatory. He was the main observer for the catalogue of southern stars, created from 1884 to 1888. He received his Ph.D in 1886 publishing works on the rotational period of Mars.
A crater on Mars and the asteroid 4588 Wislicenus are named in his honor.


Solar eclipse of January 27, 2074

An annular solar eclipse will occur on January 27, 2074. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide.


James Binney

James Jeffrey Binney, FRS, FInstP (born 12 April 1950) is a British astrophysicist. He is a professor of physics at the University of Oxford and former head of the Sub-Department of Theoretical Physics as well as an Emeritus Fellow of Merton College. Binney is known principally for his work in theoretical galactic and extragalactic astrophysics, though he has made a number of contributions to areas outside of astrophysics as well.
Education and career.
Binney took a first class BA in the Mathematical Tripos at the University of Cambridge in 1971, then moved to the University of Oxford, reading for a DPhil at Christ Church under Dennis Sciama, which he completed in 1975. He was a visiting scholar at the Institute for Advanced Study, Princeton in 1983–87 and again in the fall of 1989. After holding several post-doctoral positions, including a junior research fellowship at Magdalen College, and a position at Princeton University, Binney returned to Oxford as a university lecturer and fellow and tutor in physics at Merton College in 1981. He was subsequently made ad hominem reader in theoretical physics in 1991 and professor of physics in 1996.
Binney has received a number of awards and honours for his work, including the Maxwell Prize of the Institute of Physics in 1986, the Brouwer Award of the American Astronomical Society in 2003, the Dirac Medal in 2010, and the Eddington Medal in 2013. He has been a fellow of the Royal Astronomical Society since 1973, and was made a Fellow of the Royal Society and a fellow of the Institute of Physics, both in 2000. He sits on the European Advisory Board of Princeton University Press.
Interests.
Binney's research interests have included:
Publications.
Binney has authored over 200 articles in peer-reviewed journals and several textbooks, including "Galactic Dynamics", which has long been considered the standard work of reference in its field.
Books:


HIPAS Observatory

The HIPAS (HIgh Power Auroral Stimulation) Observatory was a research facility, built to study the ionosphere and its influence on radio communications. It was located 25 miles east of Fairbanks, Alaska in the Fairbanks North Star Borough area.
It was operated by the UCLA plasma physics laboratory from 1986 through 2007. A unique capability at that time, it could radiate 70 MW ERP at either 2.85 MHz or 4.53 MHz. These frequencies are close to a multiple of 2 and 3 of the electron gyro-frequency at ionospheric altitudes. Sending a pulse of HF-radio waves upward could accelerate the electrons in the ionosphere. Somewhat like waves on the ocean, the character of the ionosphere could be inferred from the backscatter signal. Other experiments attempted to combine RF and visible excitation where the latter probed metal ions such as sodium.
The HIPAS facility also used a LIDAR (LIght Detection And Ranging) instrument. Other projects included:
The High Frequency Active Auroral Research Program (HAARP) is a similar facility funded jointly by the US Air Force and US Navy.
The HIPAS facility was shut down and much of the equipment sold as surplus in the Spring of 2010.


List of unsolved problems in geoscience

This list provides references to notable unsolved problems in geoscience.


List of solar eclipses visible from Ukraine

This list of solar eclipses seen from Ukraine enumerates the solar eclipses that were seen and will be seen in Ukraine.


Julian Thornton-Duesbery

Julian Percy Thornton-Duesbery (7 September 1902 – 1 April 1985) was a British Church of England priest and academic. He was Master of St Peter's Hall, Oxford (later known as St Peter's College) from 1940 to 1944, and from 1955 to 1968. He also served as Principal of Wycliffe Hall, Oxford, an Anglican theological college, from 1944 to 1955.
Early life.
Thornton-Duesbery was born at Isle House, Godmanchester on 7 September 1902 to a clergyman, Charles Thornton-Duesbury, who would later become Bishop of Sodor and Man. He was educated at Rossall School, then an all-boys public school in Lancashire. He then matriculated into Balliol College, Oxford where he studied classics. He obtained first class honours in "Honour Moderations" in 1923, and first class honours in "Literae Humaniores" in 1925. He then joined Wycliffe Hall, Oxford, where he studied theology. He obtained first class honours in 1926 and was awarded the Junior Greek Testament Prize.
Career.
Ordained ministry.
Thornton-Duesbery was ordained in the Church of England as a deacon in 1926 and as a priest in 1927. He served at his alma mater, Wycliffe Hall, Oxford as chaplain from 1926 to 1927 and then as Vice-Principal from 1927 to 1933. In May 1928, he was additionally appointed Chaplain of Corpus Christi College, Oxford.
From 1940 to 1945, while also Master of St Peter's Hall for the first time, Thornton-Duesbery was Rector of Church of St Peter-le-Bailey, Oxford. He was also a Select Preacher to the University of Oxford between 1943 and 1945.
After retiring from the mastership in 1968, he moved to Liverpool where he was appointed Canon Theologian of the Liverpool Cathedral. He was appointed Canon Emeritus in 1977 on his retirement.
Academic career.
From 1928 to 1933, Thornton-Duesbery was a fellow and the librarian of Corpus Christi College, Oxford; this was in addition to his chaplaincy to the college and leadership role at Wycliffe Hall. In July 1933, he left his university focused life to enter the world of schooling. He was invited by Francis Graham Brown, the Anglican Bishop in Jerusalem, to become the Headmaster of St. George's School, an Anglican boys school in Jerusalem.
In 1940, he was appointed Master of St Peter's Hall, Oxford in succession to Christopher Chavasse. In 1944, he left St Peter's and was appointed Principal of Wycliffe Hall, Oxford. He replaced John Taylor who had been appointed Bishop of Sodor and Man. In 1955, he was once more appointed Master of St Peter's Hall. During his leadership, the then Permanent Private Hall achieved full collegiate status within the University of Oxford, becoming St Peter's College in 1961.


George Roupell

Brigadier George Rowland Patrick Roupell (7 April 1892 – 4 March 1974) was born in Tipperary and was an Irish born recipient of the Victoria Cross, the highest and most prestigious award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces.
Early life and military career.
George Roupell was born into a military family; his father, Francis F. F. Roupell, having served with the British Army in the 70th Regiment and commanded the 1st Battalion, East Surrey Regiment between 1895 and 1899. George's father had married Edith Maria Bryden at Kingston in 1887.
George was educated at Rossall School and the Royal Military College, Sandhurst. He was commissioned in the East Surrey Regiment, 2 March 1912 and was appointed lieutenant on 29 April 1914, shortly before the outbreak of the First World War.
World War I.
At the outbreak of war, the 1st Battalion the East Surreys were deployed as part of the British Expeditionary Force (BEF) into northern Belgium. Roupell commanded a platoon in the BEF's first major action; the Battle of Mons in August 1914. Roupell kept a diary throughout the war which has since been a useful, and sometimes humorous, source of insight and observation on the events that he witnessed and participated in. In the trenches at Mons he recounted how he had to hit his men on the backside with his sword in order to gain their attention and remind them to fire low as they had been taught!
Soon after, following the retreat from Mons in September, Roupell led his platoon in the first Battle of the Aisne. Once again, he came under heavy fire, this time while crossing the Aisne on a raft. The Surreys' advance was pushed back with heavy casualties.
Early the following year, during the continued fighting around Ypres, Roupell was 23 years old, when the following deed took place for which he was awarded the VC. His citation reads:
For most conspicuous gallantry and devotion to duty on 20 April 1915, when he was commanding a company of his battalion in a front trench on "Hill 60," which was subjected to a most severe bombardment throughout the day. Though wounded in several places, he remained at his post and led his company in repelling a strong German assault. During a lull in the bombardment he had his wounds hurriedly dressed, and then insisted in returning to his trench, which was again being subjected to severe bombardment. Towards evening, his company being dangerously weakened, he went back to his battalion headquarters, represented the situation to his commanding officer, and brought up reinforcements, passing backwards and forwards over ground swept by heavy fire. With these reinforcements he held his position throughout the night, and until his battalion was relieved next morning.
This young officer was one of the few survivors of his company, and showed a magnificent example of courage, devotion and tenacity, which undoubtedly inspired his men to hold out till the end.
He was decorated with his VC by King George V on 12 July 1915. In addition to his Victoria Cross he was awarded the Russian Order of St George (4th Class) and the French Croix de Guerre, and was Mentioned in Despatches.
He was retrospectively appointed temporary Captain 29 December 1914, to the 20 April 1915, inclusive and again later the same year.
Roupell was aboard when it was captured and sunk in the channel in October 1916.
Roupell was promoted to acting brigade major on 29 December 1917. On 9 May 1918 he was seconded to the general staff at the rank of temporary major.
Inter-war.
Following the end of hostilities in Europe, Captain Roupell, still acting major, was promoted to acting lieutenant colonel in charge of Battalion between December 1918 and March 1919. His appointment to the general staff was confirmed on 1 July 1919.
During this time he was attached to the allied force under Edmund Ironside and sent to support Tsarist Russians as part of the Allied intervention in the Russian Civil War. On a visit to a Tsarist unit, they mutinied and Roupell and others were taken prisoner near Arkhangelsk, sent to Moscow and finally repatriated in 1920.
Early in 1921, Roupell married Doris P. Sant in Paddington. Daughter Phoebe and son Peter were born in 1922 and 1925 respectively.
Roupell's inter-war military career continued with appointments as staff captain (1921), brigade major (1926) and promotion to substantive major (1928).
During the inter-war period, Roupell served in Gibraltar, the Regimental Depot, India and the Sudan and he attended the Staff College, Camberley. As major (GSO2), Roupell spent two years from 1929 at the Royal Military College of Canada
and in 1934 a year with the British troops in China. Following his return, he was promoted to lieutenant colonel (1935).
World War II.
At the outbreak of the Second World War, in September 1939, Roupell was promoted to colonel and, promoted to acting brigadier placed in command of 36th Infantry Brigade from 7 October 1939.
Roupell's 36th Brigade were deployed as part of the 12th (Eastern) Infantry Division in April 1940 and became part of the British Expeditionary Force (BEF), taking part in the Battle of France. The German thrust near the Somme river towards Abbeville eventually cut off the BEF, northern French and Belgian forces from the rest of France. Roupell's brigade headquarters near Doullens was attacked by enemy troops and on being told of the threat Roupell is reported to have exclaimed: "Never mind the Germans. I'm just going to finish my cup of tea." When the brigade headquarters was overrun on 20 May 1940, Roupell gave the order for the survivors to split up into small groups and endeavour to re-contact Allied troops. Roupell, with a captain and French interpreter, avoided capture, hiding by day and walking at night for over a month. They arrived at a farm near Rouen where the two officers remained for almost two years, working as labourers. With the help of the French Resistance they were moved through unoccupied France into non-belligerent Spain, finally boarding ship in Gibraltar and returning to the United Kingdom. Following his return he was appointed commanding officer of the 114th Infantry Brigade, part of the 38th (Welsh) Infantry Division, on 18 March 1943, a command he held until 2 November that year. He was appointed as garrison commander at Chatham, where he remained until retirement.
Post-War.
In 1946 Roupell was formally retired from the army on retirement pay and granted the honorary rank of brigadier.
 and, at the age of 58, excused from the reserve list of officers in 1950.
He was appointed a Deputy Lieutenant of Surrey in 1953.
In 1954 he was appointed Colonel of the East Surreys, succeeding Arthur Dowler, and was to be the last Colonel of The East Surrey Regiment, relinquishing office in 1959 when amalgamation with The Queen's Royal Regiment took place to form the Queen's Royal Surrey Regiment.
He was appointed a Companion of the Order of the Bath in 1956.
George Roupell died in Shalford, Surrey, on 4 March 1974 (aged 82). His body was cremated at Guildford Crematorium.
References.
Listed in order of publication year


Korean Astronomical Society

The Korean Astronomical Society is a non-profit learned society in South Korea that aims a supporting astronomical scholarship, technological development, education, and the spread of astronomical knowledge. It operates the Journal of the Korean Astronomical Society.
The KAS was founded on 21 March 1965, and presently has over 700 members. It holds meetings in spring and autumn of each year. The KAS is a member organisation of the International Astronomical Union, which it joined in 1973, and hosted the IAU Asia-Pacific Regional Meeting in 1996 and 2014. It also co-hosted the International Astronomy Olympiad in 2012.


Jani Radebaugh

Jani Radebaugh (; ) is an American planetary scientist and professor of geology at Brigham Young University who specializes in field studies of planets. Radebaugh's research focuses on Saturn's moon Titan, Jupiter's moon Io, our own Moon, Mars and Pluto. Radebaugh is a Science Team member of the Dragonfly (spacecraft) mission to Titan, the IVO Io mission proposal, and the Mars Median project. She was an Associate Team Member of the Cassini-Huygens RADAR instrument from 2008-2017, and was a graduate student scientist for Io for the Galileo mission. She does science outreach through her work as an expert contributor to the Science/Discovery program "How the Universe Works" and other television and radio programs. In December 2012, Radebaugh and her colleagues on the Cassini mission announced the discovery of Vid Flumina, a liquid methane river on Saturn's moon Titan over long and resembling the Nile river.
Career.
Radebaugh received a BS from Brigham Young University in Physics and Astronomy and a PhD from the University of Arizona in Planetary Science. She has been a professor of Geological Sciences at Brigham Young University since 2006 (full professor since 2019). She has conducted field research in terrestrial locations as Earth analogues for geological features on other worlds within the solar system, including the Saharan, Arabian and Namib deserts to study giant sand dunes similar to those on Saturn's moon Titan, lava lakes in the Ethiopian Afar valley, Vanuatu, and Kilauea as analogues for the active lava lakes of Jupiter's moon Io. She traveled to Iran's Lut Desert to study wind-carved ridges, termed yardangs, which are found on Mars, Venus and Titan and has spent four seasons (05-06, 08-09, 13-14, 16-17) in Antarctica with the U.S. Antarctic Search for Meteorites, where she helped recover meteorite samples from around the solar system including the Moon and Mars.
She has repeatedly appeared as an expert contributor to the Science/Discovery program "How the Universe Works," as well as other television programs on BBC and Nova. Radebaugh has appeared on the "Science Channel's", "The Planets and Beyond". She has analyzed data from the Cassini RADAR instrument and contributed to the formulation of the Dragonfly rotorcraft lander mission proposal. She was also involved in the Galileo Mission, the Io Volcanoes Observer mission proposal, and the Median project for Mars.
Personal life.
Radebaugh lives in Provo, Utah and is a member of The Church of Jesus Christ of Latter-day Saints. She was married in 2020.
Inclusion.
In November 2018, Radebaugh was quoted in an article in response to the American Geophysical Union (AGU) action on removing a Brigham Young University job posting due to homophobic bias by the university's hiring code of conduct. Radebaugh supported the hiring advertisement's inclusion on AGU job boards, stating that ideological diversity was important towards a constructive dialogue about inclusion in science.


Talcott Mountain Science Center

Talcott Mountain Science Center for Student Involvement ("TMSC") is a not-for-profit 501c(3) corporation in Avon, Connecticut. It is dedicated to the improvement of science education and does so by working directly with students, teachers, and the general public.
History.
TMSC was established in 1967 under a program of the U.S. Department of Education. Its founders were part of the Avon Public School district and included Superintendent Francis Driscoll and science teachers Donald P. La Salle and George C. Atamian. Its campus atop Talcott Mountain is a former Project Nike missile radar site ("HA-85") that formed part of the U.S. defenses during the Cold War. Initially three small buildings and a guard shack, the Center today houses four main campus buildings with classrooms and laboratories, as well as a weather research station, two observatories, the largest teaching planetarium in Connecticut and - within the surrounding 15 miles - a large visible model of the solar system.
Activities.
The Center provides direct science education in schools in central Connecticut, online resources via the internet, teacher training in science methods, as well as public programs by appointment for students and adults on weekends and evenings, vacations and summers.
Courses include general science for younger students, and enrichment and student-based research in astronomy, chronobiology, computers, ecology, geology, green energy, magic & science, meteorology, music technology, robotics, and video production.
The Center produces curriculum for its own use as well as on a contracted basis for schools and projects. It has originated a number of nationwide educational projects under the U.S. Department of Education and the National Science Foundation. It has been an international consultant to overseas schools in Northern Africa, Eastern Europe and the Mediterranean region.
The Center houses the Talcott Mountain Academy for Science, Mathematics and Technology, a private independent co-educational day school centered on science and providing all academic subjects in grades K-8.


Galactic plane

The galactic plane is the plane on which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles. In actual usage, the terms "galactic plane" and "galactic poles" usually refer specifically to the plane and poles of the Milky Way, in which Planet Earth is located.
Some galaxies are irregular and do not have any well-defined disk. Even in the case of a barred spiral galaxy like the Milky Way, defining the galactic plane is slightly imprecise and arbitrary since the stars are not perfectly coplanar. In 1959, the IAU defined the position of the Milky Way's north galactic pole as exactly RA = , Dec = in the then-used B1950 epoch; in the currently-used J2000 epoch, after precession is taken into account, its position is RA , Dec . This position is in Coma Berenices, near the bright star Arcturus; likewise, the south galactic pole lies in the constellation Sculptor.
The "zero of longitude" of galactic coordinates was also defined in 1959 to be at position angle 123° from the north celestial pole. Thus the zero longitude point on the galactic equator was at , (B1950) or , (J2000), and its J2000 position angle is 122.932°. The galactic center is located at position angle 31.72° (B1950) or 31.40° (J2000) east of north.


July 2047 lunar eclipse

A total lunar eclipse will take place on July 7, 2047. It will last 1 hour and 41 minutes and will plunge the full Moon into deep darkness, as it passes right through the centre of the Earth's umbral shadow. While the visual effect of a total eclipse is variable, the Moon may be stained a deep orange or red colour at maximum eclipse. This will be a great spectacle for everyone who sees it. The partial eclipse will last for 3 hours and 39 minutes in total.
The moon will pass through the center of the Earth's shadow. Totality will last 102 minutes, the maximum for this Saros series.
Visibility.
It will be completely visible over most of the Pacific Ocean, seen rising over Australia and Eastern Asia, and setting over North and South America.
Related lunar eclipses.
Half-Saros cycle.
A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros). This lunar eclipse is related to two annular solar eclipses of Solar Saros 137.


John Guest (geologist)

John Edward Guest (6 December 1938 – 19 May 2012), was a British volcanologist and planetary scientist.
Education and family.
Guest was born in London, England). He studied at University College London (UCL) and he graduated there in 1962. He and Mary Guest, his wife, had two sons, Ben and James
Career.
Guest remained as an employee of his "alma mater" for the remainder of his career. He worked on his PhD under Sydney Ewart Hollingworth on the subject of tertiary ignimbrites in the Chilean Andes, where Hollingworth had been mapping the geology.
Planetary geology and physical volcanology were developed at UCL under his auspices. He did research on a number of volcanoes around the World, but most notably Mount Etna in Sicily. He was the leader of the United Kingdom's efforts in a long-term collaboration with Italy to study the evolution of Mount Etna and, for the first time in over 100 years, make a geological map of it.
In 1984, he was asked by the government of the United Kingdom to assess the volcanic threat to the British military personnel at a NATO base in Sicily. After submitting his report, it found its way - the following day - into the Italian press with the headline, "Bye, bye, Naples!" and Guest used his skills as required to allay the concerns of Italian politicians.
He did postdoctoral study on lunar craters: he worked with Gilbert Fielder, a vocal supporter of the volcanic origin of the craters, at the university observatory. Guest soon rejected Fielder's commonly-held belief and instead supported the meteorite-impact mechanism; the new data unequivocally supported his view. He joined NASA's programme for planetary exploration, including the 1973 "Mariner 10" mission to Mercury and the 1975 Viking programme to Mars. In 1980, he founded the first NASA Regional Planetary Image Facility outside of the U.S.A. at UCL where he taught many leading international scientists including Rosaly Lopes, Chris Kilburn and Ben Bussey. He was involved with scientists from the Soviet Union on their 1988 "Phobos 2" mission to Mars and further with the American 1989 "Magellan" mission to Venus. He contributed to the first geological map of Mercury and the first detailed map of eastern equatorial Mars, along with Ron Greeley. Guest and Greeley helped to select the "Viking 2" landing site. With Philippe Masson, , and Marcello Fulchignoni, he founded the European Planetary Geology Consortium in 1976 to foster cooperation in planetary surface studies. In 1999, he moved from the UCL observatory to the Department of Geological Sciences.
As a story-teller, educator and colleague, he was much-loved, supportive, inspirational to generations of students and considered his role more as a vocation than a job. Showing his great humour, he duped his students into believing in rats occupying lava tubes and that the principal danger to be encountered while working amongst rope-like Hawaiian "pahoehoe" lavas was a poisonous snake. He had a great talent for interpreting geology from morphology, even from photographs. Very inquisitive, he was fascinated by the international cultures and customs he encountered on his travels. His fast thinking and remarkable skills of magnanimity were greatly admired: he would address the nub of a problem quickly and thus had a very influential effect in discussions, debates, decision-making and project planning.
He died at home in Church Stretton, Shropshire.


Lichun

Traditional Chinese calendar divides a year into 24 solar terms. Lìchūn, "Risshun", "Ipchun", or "Lập xuân" is the 1st solar term. It begins when the Sun reaches the celestial longitude of 315° and ends when it reaches the longitude of 330°. It more often refers in particular to the day when the Sun is exactly at the celestial longitude of 315°. In the Gregorian calendar, it usually begins around February 4 and ends around February 18 (February 19 East Asia time). It's also the beginning of a sexagenary cycle.
Pentads.
Each solar term can be divided into 3 pentads (候). They are: first pentad (初候), second pentad (次候) and last pentad (末候). Pentads in Lichun include:
Customs.
China.
Lichun traditionally signifies the beginning of spring in East Asian cultures. Chinese New Year is celebrated around this time. Farmers often celebrate the beginning of Lichun with special village events, worship and offerings to the Taoist and Buddhist gods and ceremonies for a blissful and prosperous new year. In China, people eat "chūnbǐng" (春餅) on this day.
According to some schools of Feng Shui, if you are born after Chinese New Years but before or even on the first day of Lichun you are considered the zodiac animal of the previous Chinese lunar year.
In the lunisolar calendar, New Year's Day might be before or after Lichun. A year without Lichun is called 無春年 ("no spring year"). 無春年 is also known as 寡婦年 ("widow year") in northern China or 盲年 ("blind year") in southern China. Marriage is believed to be unlucky in a year without Lichun.
In the Republic of China, Lichun has been Farmer's Day since 1941.
In Singapore, there is a practice of depositing money into bank accounts on Lichun which many believe will bring them good fortune.
Korea.
Ipchun is the first season of the new year, so there are many farming-related events.
In Ipchun, families, regardless of the city or countryside, put their writings on walls or thresholds as a blessing event.
These writings are also called Ipchunchuk, Chunchuk, Ipchunseo, Ipchunbang, and Chunbang.
Those who know the letters write themselves, and those who do not know how to write, ask others to write them.
It is said that it is good to attach it at the time of Ipchun, but it is not written in the house where the funeral is held.
In popular culture.
China.
Lichun was frequently mentioned in literature. The most famous reference is probably Du Fu's (杜甫) "shi" (詩), simply titled "Lìchūn" (立春):
This poem tells us about the traditional custom of eating "chūnbǐng" (春餅) on this day.


Giuseppe Asclepi

Giuseppe Maria Asclepi (1706–1776) was an Italian astronomer and physician. He was a Jesuit and director of the observatory at the Collegio Romano.
The lunar crater Asclepi is named after him.


WASP-28b

WASP-28b is an extrasolar planet discovered in 2010 by the Wide Angle Search for Planets (WASP) project orbiting WASP-28, a magnitude 12 star also known as 1SWASP J233427.87-013448.1 and 2MASS J23342787-0134482. Since it orbits its star very closely, the planet is a strongly irradiated hot Jupiter. As seen from the Earth, WASP-28b transits its host star every 3.41 days taking about 3 hours to do so.
The planet was observed by the Kepler spacecraft during the K2 mission engineering campaign in February 2014 as part of an early science demonstration. It was also observed from December 2016 to March 2017 during K2's campaign 12 which allowed a refinement of the system parameters.
Internal structure.
The planet seems to be a gas giant with a low core mass (<~10M(Earth)) and a low heavy elements content (Z<~0.2).


Peter Winterbottom

Peter James Winterbottom (born 31 May 1960 in Otley, West Yorkshire), is a former England rugby union footballer who played as an openside flanker. He was England's most-capped openside (with 58 caps) until being overtaken by Neil Back in 2003. He made his England debut on 2 January 1982 against Australia, and his final appearance on 20 March 1993 against Ireland.
Winterbottom was known for his work rate, durability, hard tackling and courage. He was selected on two British and Irish Lions tours in 1983 and 1993, both to New Zealand, where he impressed the locals with his fine play, albeit on losing sides. He was the second England player to reach 50 caps, after Rory Underwood, and was inducted onto the Twickenham "Wall of Fame" in November 2005.
Winterbottom played club rugby for Headingley, Harlequins and also for Hawkes Bay in New Zealand and Transvaal in South Africa
After rugby.
Since his playing career ended, Winterbottom carved out a career in finance. He worked as a Corporate bond broker for Tullett & Tokyo Ltd and BGC Partners alongside Ben Clarke, but left BGC in 2008 to join interdealer broker Creditex.
Peter is currently Director Rugby at Esher Rugby Football Club.
Personal life.
Winterbottom is the uncle of Swiss-born James Leuzinger, who represented Great Britain at the 2006 Winter Olympics.


Stephen P. Laurie

Stephen P. Laurie is a British amateur astronomer. He is a prolific discoverer of asteroids and comets, although his profession is that of an actuary. He has also worked on searches for dwarf stars and discovered a supernova (SN 1997bq in NGC 3147) in 1997.
Laurie has named five asteroids he discovered from the Church Stretton area — 7603 Salopia (named after Shropshire,) 9421 Violilla, 9428 Angelalouise, 10216 Popastro and 11626 Church Stretton — all discovered at observatory 966 Church Stretton and nearby location Ragdon (observatory J17). Laurie lives and works in the Church Stretton area.


XO Project

The XO Project is an international team of amateur and professional astronomers tasked with identifying extrasolar planets. They are led by Peter McCullough of the Space Telescope Science Institute. It is primarily funded by NASA's Origins Program and the Director's Discretionary Fund of the Space Telescope Science Institute.
Duties.
Preliminary identification of possible star candidates starts at the Haleakala telescope in Hawaii by a team of professional astronomers. Once they identify a star that dims slightly from time to time, the information is forwarded to a team of amateur astronomers who then investigate for additional evidence suggesting this dimming is caused by a transiting planet. Once enough data is collected, it is forwarded to the University of Texas McDonald Observatory to confirm the presence of a transiting planet by a second team of professional astronomers.
Equipment.
McCullough and his team employed a relatively inexpensive telescope called an XO Telescope, made from commercial equipment, to search for extrasolar planets. This telescope consists of two 200-millimeter telephoto camera lenses, and resembles binoculars in shape. It stands on the summit of the Haleakalā volcano in Hawaii. Their first discovery of a Jupiter-sized planet orbiting a Sun-like star 600 light-years from Earth in the constellation Corona Borealis—XO-1b—was reported May 16, 2006 on Newswise.
In 2016 three similar double telescopes were operating, two in Spain and one in Utah.


Eric Burgess

Eric Burgess (1920 – March 2005) was an English freelance consultant, lecturer and journalist, who wrote about the Pioneer program of space missions since the first tests in 1957. He was the science correspondent of the "Christian Science Monitor" in the period of many of the planetary probe launches, and was often the senior science reporter present at many of those events.
Burgess is credited with the original idea that the Pioneer probes should carry a message for extraterrestrial intelligences. He approached Carl Sagan about his idea, which eventually resulted in the Pioneer plaque. Burgess was a fellow of the Royal Astronomical Society and British Interplanetary Society, and an associate fellow of the American Institute of Aeronautics and Astronautics.
Burgess and Arthur C. Clarke were both charter members of the British Interplanetary Society and lifelong friends. While Clarke claimed he invented the idea of using three satellites in geostationary orbit to create the global communication relay in common use today (see: book dust jacket front fold over sleeve of The Exploration of Space, A.C. Clarke, Harper Bros., 1951), Burgess claimed to have given the idea to Clarke in the late 1940s. Shortly before his death Burgess had a large collection of film and printed media on the subject of rocketry and space exploration that may have been donated by his heirs to a local library. Perhaps his greatest contribution other than the claim of having the idea for geosynchronous satellite communication networks (disputed with characteristic droll humor by Clarke) was his chronicling of the initial exploration of the solar system (see: bibliography). He was also the science adviser for the James Bond film Moonraker which received an Academy Award nomination for its visuals which Burgess helped edit for accuracy.


Ralph Arthur Penrhyn Clements

Major General Ralph Arthur Penrhyn Clements, (9 February 1855 – 2 April 1909), commonly known as R. A. P. Clements, was a senior British Army officer.
Clements, the son of a churchman, fought in the Xhosa War of 1877–1878 and the Anglo-Zulu War as a junior officer. He was twice wounded during the Third Anglo-Burmese War while serving as a brigade major, being mentioned in dispatches. After commanding a battalion of the South Wales Borderers during the late 1890s, he was appointed a brigade commander during the Second Boer War. Clements commanded the Colesberg front in early 1900, but was surprised at the Battle of Nooitgedacht in December, managing to extricate his force from the latter. After the Boer War he served in India, rising to divisional command before his death.
Early life and career.
Clements was born at Upton St Leonards on 9 February 1855, the son of Reverend Jacob Clements, a local sub-dean and Canon Residentiary, and was educated at the Rossall School. He transferred from the militia to the British Army on 2 December 1874, and served as a lieutenant of the 24th Regiment of Foot in South Africa. Clements fought at the Battle of Nyumaga during the Xhosa War of 1877–1878, being mentioned in dispatches on 26 February 1878. He became adjutant of his battalion on 27 July 1879 and served at the Battle of Ulundi during the 1879 Anglo-Zulu War. For his service, Clements received the South Africa Medal with clasp; he continued to serve with the regiment when it became the South Wales Borderers and was promoted to captain on 4 December 1880, becoming a company commander.
Clements became battalion adjutant again on 26 October 1882, holding the position until promoted to major on 24 February 1886. He served as a brigade major during the Burma Expedition and as Assistant Provost Marshal, being twice wounded in battle (once severely) and mentioned in dispatches on 22 June 1886. Clements rejoined his battalion in early 1886 and remained with them until 1889. Clements received the India General Service Medal with clasps and was brevetted lieutenant colonel in July 1887 for his actions. Awarded the Distinguished Service Order in 1891, he was made an Aide-de-camp to Queen Victoria on 2 December 1896. On 8 April 1897 Clements was promoted to command of the 2nd Battalion, South Wales Borderers.
Second Boer War.
During the Second Boer War, on 20 November 1899 Clements was selected to take command of the unit that became the 12th Brigade of the 6th Division at Aldershot. He departed for South Africa on 4 December with the temporary rank of major general and the substantive rank of colonel. Clements took over command on the Colesberg front from Major General John French in late January and held it with lesser forces against the attacks of Boer commander Koos de la Rey. On 12 February, after the action at Pink Hill, Clements shortened his line in the face of the Boer advance by retreating to Rensburg siding. After the victories of Field Marshal Frederick Roberts on the western front, the Boers retreated and Clements took Colesberg on 28 February.
He led his brigade (column) under the command of Archibald Hunter during the advance into the Brandwater Basin during July 1900. Due to the slow movement of his supply convoy, the advance of the column into the Drakensberg was delayed until 20 July. For the attack of Hunter's force, Clements and Arthur Paget's columns were tasked with attacking Slabbert's Nek in the Boer centre. Slebbert's Nek was taken with little resistance and the columns joined Hunter and advanced to Fouriesburg, after which a large Boer force under General Marthinus Prinsloo surrendered to them.
Clements' column moved into the Magalies valley in September and remained there for the next three months, burning farms there so effectively that the area became a "blackened desert" according to the historian Thomas Pakenham. Clements encamped at Nooitgedacht on 8 December, in a position that provided him with a water supply and heliograph communication, though dominated by the Magaliesberg. His 1,200-strong force was attacked at dawn on 13 December by more than 1,500 Boers under de la Rey and Christian Frederick Beyers. The three hundred dispersed pickets he had posted on the ridge were swiftly overrun and surrendered. After Boer fire was directed on his camp, Clements began a retreat with the remaining half of his force to Yeomanry Hill in the valley, out of range of the Boers on the ridge. Due to Boer exhaustion and looting of his camp, Clements managed an orderly retreat towards Pretoria that afternoon. Clements subsequently commanded the districts of Pretoria and Standerton-Heidelberg. He was mentioned in dispatches on 4 May 1900, 16 April 1901, and 29 July 1902, and received the Queen's medal with three clasps and the King's medal with two clasps. Following the end of the war in June 1902, he stayed on in South Africa for several months with a staff appointment.
Later life.
He was made an aide-de-camp to Edward VII in 1901 and a Companion of the Order of the Bath in 1904. On 1 February of that year, he was sent to India as a major general in the British Indian Army to command a second class district at Agra, which became the Sirhind Brigade of the 3rd (Lahore) Division under the Kitchener Reforms. Clements was appointed commander of the 4th (Quetta) Division on 1 December 1907, and died on 2 April 1909 at Quetta from complications resulting from an appendicitis operation. He was buried in the New Cemetery at Quetta.


Stellar classification

In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The "spectral class" of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature.
Most stars are currently classified under the Morgan–Keenan (MK) system using the letters "O", "B", "A", "F", "G", "K", and "M", a sequence from the hottest ("O" type) to the coolest ("M" type). Each letter class is then subdivided using a numeric digit with "0" being hottest and "9" being coolest (e.g., A8, A9, F0, and F1 form a sequence from hotter to cooler). The sequence has been expanded with classes for other stars and star-like objects that do not fit in the classical system, such as class "D" for white dwarfs and classes "S" and "C" for carbon stars.
In the MK system, a luminosity class is added to the spectral class using Roman numerals. This is based on the width of certain absorption lines in the star's spectrum, which vary with the density of the atmosphere and so distinguish giant stars from dwarfs. Luminosity class "0" or "Ia+" is used for "hypergiants", class "I" for "supergiants", class "II" for bright "giants", class "III" for regular "giants", class "IV" for "sub-giants", class "V" for "main-sequence stars", class "sd" (or "VI") for "sub-dwarfs", and class "D" (or "VII") for "white dwarfs". The full spectral class for the Sun is then G2V, indicating a main-sequence star with a surface temperature around 5,800 K.
Conventional colour description.
The conventional colour description takes into account only the peak of the stellar spectrum. In actuality, however, stars radiate in all parts of the spectrum. Because all spectral colours combined appear white, the actual apparent colours the human eye would observe are far lighter than the conventional colour descriptions would suggest. This characteristic of 'lightness' indicates that the simplified assignment of colours within the spectrum can be misleading. Excluding colour-contrast effects in dim light, in typical viewing conditions there are no green, indigo, or violet stars. Red dwarfs are a deep shade of orange, and brown dwarfs do not literally appear brown, but hypothetically would appear dim grey to a nearby observer.
Modern classification.
The modern classification system is known as the "Morgan–Keenan" (MK) classification. Each star is assigned a spectral class from the older Harvard spectral classification and a luminosity class using Roman numerals as explained below, forming the star's spectral type.
Other modern stellar classification systems, such as the UBV system, are based on color indices—the measured differences in three or more color magnitudes. Those numbers are given labels such as "U−V" or "B−V", which represent the colors passed by two standard filters (e.g. "U"ltraviolet, "B"lue and "V"isual).
Harvard spectral classification.
The "Harvard system" is a one-dimensional classification scheme by astronomer Annie Jump Cannon, who re-ordered and simplified the prior alphabetical system by Draper (see next paragraph). Stars are grouped according to their spectral characteristics by single letters of the alphabet, optionally with numeric subdivisions. Main-sequence stars vary in surface temperature from approximately 2,000 to 50,000 K, whereas more-evolved stars can have temperatures above 100,000 K. Physically, the classes indicate the temperature of the star's atmosphere and are normally listed from hottest to coldest.
The spectral classes O through M, as well as other more specialized classes discussed later, are subdivided by Arabic numerals (0–9), where 0 denotes the hottest stars of a given class. For example, A0 denotes the hottest stars in class A and A9 denotes the coolest ones. Fractional numbers are allowed; for example, the star Mu Normae is classified as O9.7. The Sun is classified as G2.
Conventional color descriptions are traditional in astronomy, and represent colors relative to the mean color of an A class star, which is considered to be white. The apparent color descriptions are what the observer would see if trying to describe the stars under a dark sky without aid to the eye, or with binoculars. However, most stars in the sky, except the brightest ones, appear white or bluish white to the unaided eye because they are too dim for color vision to work. Red supergiants are cooler and redder than dwarfs of the same spectral type, and stars with particular spectral features such as carbon stars may be far redder than any black body.
The fact that the Harvard classification of a star indicated its surface or photospheric temperature (or more precisely, its effective temperature) was not fully understood until after its development, though by the time the first Hertzsprung–Russell diagram was formulated (by 1914), this was generally suspected to be true. In the 1920s, the Indian physicist Meghnad Saha derived a theory of ionization by extending well-known ideas in physical chemistry pertaining to the dissociation of molecules to the ionization of atoms. First he applied it to the solar chromosphere, then to stellar spectra.
Harvard astronomer Cecilia Payne then demonstrated that the "O-B-A-F-G-K-M" spectral sequence is actually a sequence in temperature. Because the classification sequence predates our understanding that it is a temperature sequence, the placement of a spectrum into a given subtype, such as B3 or A7, depends upon (largely subjective) estimates of the strengths of absorption features in stellar spectra. As a result, these subtypes are not evenly divided into any sort of mathematically representable intervals.
Yerkes spectral classification.
The "Yerkes spectral classification", also called the "MKK" system from the authors' initials, is a system of stellar spectral classification introduced in 1943 by William Wilson Morgan, Philip C. Keenan, and Edith Kellman from Yerkes Observatory. This two-dimensional (temperature and luminosity) classification scheme is based on spectral lines sensitive to stellar temperature and surface gravity, which is related to luminosity (whilst the "Harvard classification" is based on just surface temperature). Later, in 1953, after some revisions of list of standard stars and classification criteria, the scheme was named the "Morgan–Keenan classification", or "MK", and this system remains in use.
Denser stars with higher surface gravity exhibit greater pressure broadening of spectral lines. The gravity, and hence the pressure, on the surface of a giant star is much lower than for a dwarf star because the radius of the giant is much greater than a dwarf of similar mass. Therefore, differences in the spectrum can be interpreted as "luminosity effects" and a luminosity class can be assigned purely from examination of the spectrum.
A number of different "luminosity classes" are distinguished, as listed in the table below.
Marginal cases are allowed; for example, a star may be either a supergiant or a bright giant, or may be in between the subgiant and main-sequence classifications.
In these cases, two special symbols are used:
For example, a star classified as A3-4III/IV would be in between spectral types A3 and A4, while being either a giant star or a subgiant.
Sub-dwarf classes have also been used: VI for sub-dwarfs (stars slightly less luminous than the main sequence).
Nominal luminosity class VII (and sometimes higher numerals) is now rarely used for white dwarf or "hot sub-dwarf" classes, since the temperature-letters of the main sequence and giant stars no longer apply to white dwarfs.
Occasionally, letters "a" and "b" are applied to luminosity classes other than supergiants; for example, a giant star slightly less luminous than typical may be given a luminosity class of IIIb, while a luminosity class IIIa indicates a star slightly brighter than a typical giant.
A sample of extreme V stars with strong absorption in He II λ4686 spectral lines have been given the "Vz" designation. An example star is HD 93129 B.
Spectral peculiarities.
Additional nomenclature, in the form of lower-case letters, can follow the spectral type to indicate peculiar features of the spectrum.
For example, 59 Cygni is listed as spectral type B1.5Vnne, indicating a spectrum with the general classification B1.5V, as well as very broad absorption lines and certain emission lines.
History.
The reason for the odd arrangement of letters in the Harvard classification is historical, having evolved from the earlier Secchi classes and been progressively modified as understanding improved.
Secchi classes.
During the 1860s and 1870s, pioneering stellar spectroscopist Angelo Secchi created the "Secchi classes" in order to classify observed spectra. By 1866, he had developed three classes of stellar spectra, shown in the table below.
In the late 1890s, this classification began to be superseded by the Harvard classification, which is discussed in the remainder of this article.
The Roman numerals used for Secchi classes should not be confused with the completely unrelated Roman numerals used for Yerkes luminosity classes and the proposed neutron star classes.
Draper system.
In the 1880s, the astronomer Edward C. Pickering began to make a survey of stellar spectra at the Harvard College Observatory, using the objective-prism method. A first result of this work was the "Draper Catalogue of Stellar Spectra", published in 1890. Williamina Fleming classified most of the spectra in this catalogue and was credited with classifying over 10,000 featured stars and discovering 10 novae and more than 200 variable stars. With the help of the Harvard computers, especially Williamina Fleming, the first iteration of the Henry Draper catalogue was devised to replace the Roman-numeral scheme established by Angelo Secchi.
The catalogue used a scheme in which the previously used Secchi classes (I to V) were subdivided into more specific classes, given letters from A to P. Also, the letter Q was used for stars not fitting into any other class. Fleming worked with Pickering to differentiate 17 different classes based on the intensity of hydrogen spectral lines, which causes variation in the wavelengths emanated from stars and results in variation in color appearance. The spectra in class A tended to produce the strongest hydrogen absorption lines while spectra in class O produced virtually no visible lines. The lettering system displayed the gradual decrease in hydrogen absorption in the spectral classes when moving down the alphabet. This classification system was later modified by Annie Jump Cannon and Antonia Maury to produce the Harvard spectral classification scheme.
The old Harvard system (1897).
In 1897, another astronomer at Harvard, Antonia Maury, placed the Orion subtype of Secchi class I ahead of the remainder of Secchi class I, thus placing the modern type B ahead of the modern type A. She was the first to do so, although she did not use lettered spectral types, but rather a series of twenty-two types numbered from I–XXII.
Because the 22 Roman numeral groupings didn't account for additional variations in spectra, three additional divisions were made to further specify differences: Lowercase letters were added to differentiate relative line appearance in spectra; the lines were defined as
Antonia Maury published her own stellar classification catalogue in 1897 called "Spectra of Bright Stars Photographed with the 11 inch Draper Telescope as Part of the Henry Draper Memorial", which included 4,800 photographs and Maury's analyses of 681 bright northern stars. This was the first instance in which a woman was credited for an observatory publication.
The current Harvard system (1912).
In 1901, Annie Jump Cannon returned to the lettered types, but dropped all letters except O, B, A, F, G, K, M, and N used in that order, as well as P for planetary nebulae and Q for some peculiar spectra. She also used types such as B5A for stars halfway between types B and A, F2G for stars one fifth of the way from F to G, and so on.
Finally, by 1912, Cannon had changed the types B, A, B5A, F2G, etc. to B0, A0, B5, F2, etc. This is essentially the modern form of the Harvard classification system. This system was developed through the analysis of spectra on photographic plates, which could convert light emanated from stars into a readable spectra.
A common mnemonic for remembering the order of the spectral type letters, from hottest to coolest, is "Oh, Be A Fine Guy/Girl: Kiss Me!".
Mount Wilson classes.
A luminosity classification known as the Mount Wilson system was used to distinguish between stars of different luminosities. This notation system is still sometimes seen on modern spectra.
Spectral types.
The stellar classification system is taxonomic, based on type specimens, similar to classification of species in biology: The categories are defined by one or more standard stars for each category and sub-category, with an associated description of the distinguishing features.
"Early" and "late" nomenclature.
Stars are often referred to as "early" or "late" types. "Early" is a synonym for "hotter", while "late" is a synonym for "cooler".
Depending on the context, "early" and "late" may be absolute or relative terms. "Early" as an absolute term would therefore refer to O or B, and possibly A stars. As a relative reference it relates to stars hotter than others, such as "early K" being perhaps K0, K1, K2 and K3.
"Late" is used in the same way, with an unqualified use of the term indicating stars with spectral types such as K and M, but it can also be used for stars that are cool relative to other stars, as in using "late G" to refer to G7, G8, and G9.
In the relative sense, "early" means a lower Arabic numeral following the class letter, and "late" means a higher number.
This obscure terminology is a hold-over from a late nineteenth century model of stellar evolution, which supposed that stars were powered by gravitational contraction via the Kelvin–Helmholtz mechanism, which is now known to not apply to main-sequence stars. If that were true, then stars would start their lives as very hot "early-type" stars and then gradually cool down into "late-type" stars. This mechanism provided ages of the Sun that were much smaller than what is observed in the geologic record, and was rendered obsolete by the discovery that stars are powered by nuclear fusion. The terms "early" and "late" were carried over, beyond the demise of the model they were based on.
Class O.
O-type stars are very hot and extremely luminous, with most of their radiated output in the ultraviolet range. These are the rarest of all main-sequence stars. About 1 in 3,000,000 (0.00003%) of the main-sequence stars in the solar neighborhood are O-type stars. Some of the most massive stars lie within this spectral class. O-type stars frequently have complicated surroundings that make measurement of their spectra difficult.
O-type spectra formerly were defined by the ratio of the strength of the He II λ4541 relative to that of He I λ4471, where λ is the radiation wavelength. Spectral type O7 was defined to be the point at which the two intensities are equal, with the He I line weakening towards earlier types. Type O3 was, by definition, the point at which said line disappears altogether, although it can be seen very faintly with modern technology. Due to this, the modern definition uses the ratio of the nitrogen line N IV λ4058 to N III λλ4634-40-42.
O-type stars have dominant lines of absorption and sometimes emission for He II lines, prominent ionized (Si IV, O III, N III, and C III) and neutral helium lines, strengthening from O5 to O9, and prominent hydrogen Balmer lines, although not as strong as in later types. Because they are so massive, O-type stars have very hot cores and burn through their hydrogen fuel very quickly, so they are the first stars to leave the main sequence.
When the MKK classification scheme was first described in 1943, the only subtypes of class O used were O5 to O9.5. The MKK scheme was extended to O9.7 in 1971 and O4 in 1978, and new classification schemes that add types O2, O3, and O3.5 have subsequently been introduced.
Spectral standards:
Class B.
B-type stars are very luminous and blue. Their spectra have neutral helium lines, which are most prominent at the B2 subclass, and moderate hydrogen lines. As O- and B-type stars are so energetic, they only live for a relatively short time. Thus, due to the low probability of kinematic interaction during their lifetime, they are unable to stray far from the area in which they formed, apart from runaway stars.
The transition from class O to class B was originally defined to be the point at which the He II λ4541 disappears. However, with modern equipment, the line is still apparent in the early B-type stars. Today for main-sequence stars, the B class is instead defined by the intensity of the He I violet spectrum, with the maximum intensity corresponding to class B2. For supergiants, lines of silicon are used instead; the Si IV λ4089 and Si III λ4552 lines are indicative of early B. At mid-B, the intensity of the latter relative to that of Si II λλ4128-30 is the defining characteristic, while for late B, it is the intensity of Mg II λ4481 relative to that of He I λ4471.
These stars tend to be found in their originating OB associations, which are associated with giant molecular clouds. The Orion OB1 association occupies a large portion of a spiral arm of the Milky Way and contains many of the brighter stars of the constellation Orion. About 1 in 800 (0.125%) of the main-sequence stars in the solar neighborhood are B-type main-sequence stars.
Massive yet non-supergiant entities known as "Be stars" are main-sequence stars that notably have, or had at some time, one or more Balmer lines in emission, with the hydrogen-related electromagnetic radiation series projected out by the stars being of particular interest. Be stars are generally thought to feature unusually strong stellar winds, high surface temperatures, and significant attrition of stellar mass as the objects rotate at a curiously rapid rate. Objects known as "B(e)" or "B[e]" stars possess distinctive neutral or low ionisation emission lines that are considered to have 'forbidden mechanisms', undergoing processes not normally allowed under current understandings of quantum mechanics.
Spectral standards:
Class A.
A-type stars are among the more common naked eye stars, and are white or bluish-white. They have strong hydrogen lines, at a maximum by A0, and also lines of ionized metals (Fe II, Mg II, Si II) at a maximum at A5. The presence of Ca II lines is notably strengthening by this point. About 1 in 160 (0.625%) of the main-sequence stars in the solar neighborhood are A-type stars.
Spectral standards:
Class F.
F-type stars have strengthening spectral lines "H" and "K" of Ca II. Neutral metals (Fe I, Cr I) beginning to gain on ionized metal lines by late F. Their spectra are characterized by the weaker hydrogen lines and ionized metals. Their color is white. About 1 in 33 (3.03%) of the main-sequence stars in the solar neighborhood are F-type stars.
Spectral standards:
Class G.
G-type stars, including the Sun, have prominent spectral lines "H" and "K" of Ca II, which are most pronounced at G2. They have even weaker hydrogen lines than F, but along with the ionized metals, they have neutral metals. There is a prominent spike in the G band of CN molecules. Class G main-sequence stars make up about 7.5%, nearly one in thirteen, of the main-sequence stars in the solar neighborhood.
Class G contains the "Yellow Evolutionary Void". Supergiant stars often swing between O or B (blue) and K or M (red). While they do this, they do not stay for long in the yellow supergiant G class, as this is an extremely unstable place for a supergiant to be.
Spectral standards:
Class K.
K-type stars are orangish stars that are slightly cooler than the Sun. They make up about 12% of the main-sequence stars in the solar neighborhood. There are also giant K-type stars, which range from hypergiants like RW Cephei, to giants and supergiants, such as Arcturus, whereas orange dwarfs, like Alpha Centauri B, are main-sequence stars.
They have extremely weak hydrogen lines, if those are present at all, and mostly neutral metals (Mn I, Fe I, Si I). By late K, molecular bands of titanium oxide become present. Mainstream theories (those rooted in lower harmful radioactivity and star longevity) would thus suggest such stars have the optimal chances of heavily evolved life developing on orbiting planets (if such life is directly analogous to earth's) due to a broad habitable zone yet much lower harmful periods of emission compared to those with the broadest such zones.
Spectral standards:
Class M.
Class M stars are by far the most common. About 76% of the main-sequence stars in the solar neighborhood are class M stars. However, class M main-sequence stars (red dwarfs) have such low luminosities that none are bright enough to be seen with the unaided eye, unless under exceptional conditions. The brightest-known M-class main-sequence star is M0V Lacaille 8760, with magnitude 6.7 (the limiting magnitude for typical naked-eye visibility under good conditions is typically quoted as 6.5), and it is extremely unlikely that any brighter examples will be found.
Although most class M stars are red dwarfs, most of the largest-ever supergiant stars in the Milky Way are M stars, such as VV Cephei, Antares, and Betelgeuse, which are also class M. Furthermore, the larger, hotter brown dwarfs are late class M, usually in the range of M6.5 to M9.5.
The spectrum of a class M star contains lines from oxide molecules (in the visible spectrum, especially TiO) and all neutral metals, but absorption lines of hydrogen are usually absent. TiO bands can be strong in class M stars, usually dominating their visible spectrum by about M5. Vanadium(II) oxide bands become present by late M.
Spectral standards:
Extended spectral types.
A number of new spectral types have been taken into use from newly discovered types of stars.
Hot blue emission star classes.
Spectra of some very hot and bluish stars exhibit marked emission lines from carbon or nitrogen, or sometimes oxygen.
Class W: Wolf–Rayet.
Once included as type O stars, the Wolf–Rayet stars of class W or WR are notable for spectra lacking hydrogen lines. Instead their spectra are dominated by broad emission lines of highly ionized helium, nitrogen, carbon, and sometimes oxygen. They are thought to mostly be dying supergiants with their hydrogen layers blown away by stellar winds, thereby directly exposing their hot helium shells. Class W is further divided into subclasses according to the relative strength of nitrogen and carbon emission lines in their spectra (and outer layers).
WR spectra range is listed below:
Although the central stars of most planetary nebulae (CSPNe) show O-type spectra, around 10% are hydrogen-deficient and show WR spectra. These are low-mass stars and to distinguish them from the massive Wolf-Rayet stars, their spectra are enclosed in square brackets: e.g. [WC]. Most of these show [WC] spectra, some [WO], and very rarely [WN].
The "Slash" stars.
The "slash" stars are O-type stars with WN-like lines in their spectra. The name "slash" comes from their printed spectral type having a slash in it (e.g. "Of/WNL").
There is a secondary group found with this spectra, a cooler, "intermediate" group designated "Ofpe/WN9". These stars have also been referred to as WN10 or WN11, but that has become less popular with the realisation of the evolutionary difference from other Wolf–Rayet stars. Recent discoveries of even rarer stars have extended the range of slash stars as far as O2-3.5If*/WN5-7, which are even hotter than the original "slash" stars.
The magnetic O stars.
They are O stars with strong magnetic fields. Designation is Of?p.
Cool red and brown dwarf classes.
The new spectral types L, T, and Y were created to classify infrared spectra of cool stars. This includes both red dwarfs and brown dwarfs that are very faint in the visible spectrum.
Brown dwarfs, stars that do not undergo hydrogen fusion, cool as they age and so progress to later spectral types. Brown dwarfs start their lives with M-type spectra and will cool through the L, T, and Y spectral classes, faster the less massive they are; the highest-mass brown dwarfs cannot have cooled to Y or even T dwarfs within the age of the universe. Because this leads to an unresolvable overlap between spectral types effective temperature and luminosity for some masses and ages of different L-T-Y types, no distinct temperature or luminosity values can be given.
Class L.
Class L dwarfs get their designation because they are cooler than M stars and L is the remaining letter alphabetically closest to M. Some of these objects have masses large enough to support hydrogen fusion and are therefore stars, but most are of substellar mass and are therefore brown dwarfs. They are a very dark red in color and brightest in infrared. Their atmosphere is cool enough to allow metal hydrides and alkali metals to be prominent in their spectra.
Due to low surface gravity in giant stars, TiO- and VO-bearing condensates never form. Thus, L-type stars larger than dwarfs can never form in an isolated environment. However, it may be possible for these L-type supergiants to form through stellar collisions, an example of which is V838 Monocerotis while in the height of its luminous red nova eruption.
Class T: methane dwarfs.
Class T dwarfs are cool brown dwarfs with surface temperatures between approximately . Their emission peaks in the infrared. Methane is prominent in their spectra.
Classes T and L could be more common than all the other classes combined if recent research is accurate. Because brown dwarfs persist for so long—a few times the age of the universe—in the absence of catastrophic collisions these smaller bodies can only increase in number.
Study of the number of proplyds (protoplanetary disks, clumps of gas in nebulae from which stars and planetary systems are formed) indicates that the number of stars in the galaxy should be several orders of magnitude higher than what was previously conjectured. It is theorized that these proplyds are in a race with each other. The first one to form will become a protostar, which are very violent objects and will disrupt other proplyds in the vicinity, stripping them of their gas. The victim proplyds will then probably go on to become main-sequence stars or brown dwarfs of the L and T classes, which are quite invisible to us.
Class Y.
Brown dwarfs of spectral class Y are cooler than those of spectral class T and have qualitatively different spectra from them. A total of 17 objects have been placed in class Y as of August 2013. Although such dwarfs have been modelled and detected within forty light-years by the Wide-field Infrared Survey Explorer (WISE) there is no well-defined spectral sequence yet and no prototypes. Nevertheless, several objects have been proposed as spectral classes Y0, Y1, and Y2.
The spectra of these prospective Y objects display absorption around 1.55 micrometers. Delorme et al. have suggested that this feature is due to absorption from ammonia, and that this should be taken as the indicative feature for the T-Y transition. In fact, this ammonia-absorption feature is the main criterion that has been adopted to define this class. However, this feature is difficult to distinguish from absorption by water and methane, and other authors have stated that the assignment of class Y0 is premature.
The latest brown dwarf proposed for the Y spectral type, WISE 1828+2650, is a > Y2 dwarf with an effective temperature originally estimated around 300 K, the temperature of the human body. Parallax measurements have, however, since shown that its luminosity is inconsistent with it being colder than ~400 K. The coolest Y dwarf currently known is WISE 0855−0714 with an approximate temperature of 250 K.
The mass range for Y dwarfs is 9–25 Jupiter masses, but young objects might reach below one Jupiter mass, which means that Y class objects straddle the 13 Jupiter mass deuterium-fusion limit that marks the current IAU division between brown dwarfs and planets.
Peculiar brown dwarfs.
Young brown dwarfs have low surface gravities because they have larger radii and lower masses compared to the field stars of similar spectral type. These sources are marked by a letter beta (β) for intermediate surface gravity and gamma (γ) for low surface gravity. Indication for low surface gravity are weak CaH, K I and Na I lines, as well as strong VO line. Alpha (α) stands for normal surface gravity and is usually dropped. Sometimes an extremely low surface gravity is denoted by a delta (δ). The suffix "pec" stands for peculiar. The peculiar suffix is still used for other features that are unusual and summarizes different properties, indicative of low surface gravity, subdwarfs and unresolved binaries. The prefix sd stands for subdwarf and only includes cool subdwarfs. This prefix indicates a low metallicity and kinematic properties that are more similar to halo stars than to disk stars. Subdwarfs appear bluer than disk objects. The red suffix describes objects with red color, but an older age. This is not interpreted as low surface gravity, but as a high dust content. The blue suffix describes objects with blue near-infrared colors that cannot be explained with low metallicity. Some are explained as L+T binaries, others are not binaries, such as 2MASS J11263991−5003550 and are explained with thin and/or large-grained clouds.
Late giant carbon-star classes.
Carbon-stars are stars whose spectra indicate production of carbon – a byproduct of triple-alpha helium fusion. With increased carbon abundance, and some parallel s-process heavy element production, the spectra of these stars become increasingly deviant from the usual late spectral classes G, K, and M. Equivalent classes for carbon-rich stars are S and C.
The giants among those stars are presumed to produce this carbon themselves, but some stars in this class are double stars, whose odd atmosphere is suspected of having been transferred from a companion that is now a white dwarf, when the companion was a carbon-star.
Class C: carbon stars.
Originally classified as R and N stars, these are also known as "carbon stars". These are red giants, near the end of their lives, in which there is an excess of carbon in the atmosphere. The old R and N classes ran parallel to the normal classification system from roughly mid-G to late M. These have more recently been remapped into a unified carbon classifier C with N0 starting at roughly C6. Another subset of cool carbon stars are the C–J-type stars, which are characterized by the strong presence of molecules of 13CN in addition to those of 12CN. A few main-sequence carbon stars are known, but the overwhelming majority of known carbon stars are giants or supergiants. There are several subclasses:
Class S.
Class S stars form a continuum between class M stars and carbon stars. Those most similar to class M stars have strong ZrO absorption bands analogous to the TiO bands of class M stars, whereas those most similar to carbon stars have strong sodium D lines and weak C2 bands. Class S stars have excess amounts of zirconium and other elements produced by the s-process, and have more similar carbon and oxygen abundances than class M or carbon stars. Like carbon stars, nearly all known class S stars are asymptotic-giant-branch stars.
The spectral type is formed by the letter S and a number between zero and ten. This number corresponds to the temperature of the star and approximately follows the temperature scale used for class M giants. The most common types are S3 to S5. The non-standard designation S10 has only been used for the star Chi Cygni when at an extreme minimum.
The basic classification is usually followed by an abundance indication, following one of several schemes: S2,5; S2/5; S2 Zr4 Ti2; or S2*5. A number following a comma is a scale between 1 and 9 based on the ratio of ZrO and TiO. A number following a slash is a more-recent but less-common scheme designed to represent the ratio of carbon to oxygen on a scale of 1 to 10, where a 0 would be an MS star. Intensities of zirconium and titanium may be indicated explicitly. Also occasionally seen is a number following an asterisk, which represents the strength of the ZrO bands on a scale from 1 to 5.
Classes MS and SC: intermediary carbon-related classes.
In between the M and S classes, border cases are named MS stars. In a similar way, border cases between the S and C-N classes are named SC or CS. The sequence M → MS → S → SC → C-N is hypothesized to be a sequence of increased carbon abundance with age for carbon stars in the asymptotic giant branch.
White dwarf classifications.
The class D (for Degenerate) is the modern classification used for white dwarfs—low-mass stars that are no longer undergoing nuclear fusion and have shrunk to planetary size, slowly cooling down. Class D is further divided into spectral types DA, DB, DC, DO, DQ, DX, and DZ. The letters are not related to the letters used in the classification of other stars, but instead indicate the composition of the white dwarf's visible outer layer or atmosphere.
The white dwarf types are as follows:
The type is followed by a number giving the white dwarf's surface temperature. This number is a rounded form of 50400/"T"eff, where "T"eff is the effective surface temperature, measured in kelvins. Originally, this number was rounded to one of the digits 1 through 9, but more recently fractional values have started to be used, as well as values below 1 and above 9.
Two or more of the type letters may be used to indicate a white dwarf that displays more than one of the spectral features above.
Extended white dwarf spectral types.
A different set of spectral peculiarity symbols are used for white dwarfs than for other types of stars:
Non-stellar spectral types: Classes P and Q.
Finally, the classes P and Q, left over from the Draper system by Cannon, are occasionally used for certain non-stellar objects. Type P objects are stars within planetary nebulae and type Q objects are novae.
Stellar remnants.
Stellar remnants are objects associated with the death of stars. Included in the category are white dwarfs, and as can be seen from the radically different classification scheme for class D, non-stellar objects are difficult to fit into the MK system.
The Hertzsprung-Russell diagram, which the MK system is based on, is observational in nature so these remnants cannot easily be plotted on the diagram, or cannot be placed at all. Old neutron stars are relatively small and cold, and would fall on the far right side of the diagram. Planetary nebulae are dynamic and tend to quickly fade in brightness as the progenitor star transitions to the white dwarf branch. If shown, a planetary nebula would be plotted to the right of the diagram's upper right quadrant. A black hole emits no visible light of its own, and therefore would not appear on the diagram.
A classification system for neutron stars using Roman numerals has been proposed: type I for less massive neutron stars with low cooling rates, type II for more massive neutron stars with higher cooling rates, and a proposed type III for more massive neutron stars (possible exotic star candidates) with higher cooling rates. The more massive a neutron star is, the higher neutrino flux it carries. These neutrinos carry away so much heat energy that after only a few years the temperature of an isolated neutron star falls from the order of billions to only around a million Kelvin. This proposed neutron star classification system is not to be confused with the earlier Secchi spectral classes and the Yerkes luminosity classes.
Replaced spectral classes.
Several spectral types, all previously used for non-standard stars in the mid-20th century, have been replaced during revisions of the stellar classification system. They may still be found in old editions of star catalogs: R and N have been subsumed into the new C class as C-R and C-N.
Stellar classification, habitability, and the search for life.
While humans may eventually be able to colonize any kind of stellar habitat, this section will address the probability of life arising around other stars.
Stability, luminosity, and lifespan are all factors in stellar habitability. We only know of one star that hosts life, and that is our own—a G-class star with an abundance of heavy elements and low variability in brightness. It is also unlike many stellar systems in that it only has one star in it (see Binary System Habitability).
Working from these constraints and the problems of having an empirical sample set of only one, the range of stars that are predicted to be able to support life as we know it is limited by a few factors. Of the main-sequence star types, stars more massive than 1.5 times that of the Sun (spectral types O, B, and A) age too quickly for advanced life to develop (using Earth as a guideline). On the other extreme, dwarfs of less than half the mass of our Sun (spectral type M) are likely to tidally lock planets within their habitable zone, along with other problems (see Habitability of red dwarf systems). While there are many problems facing life on red dwarfs, many astronomers continue to model these systems due to their sheer numbers and longevity.
For these reasons NASA's Kepler Mission is searching for habitable planets at nearby main-sequence stars that are less massive than spectral type A but more massive than type M—making the most probable stars to host life dwarf stars of types F, G, and K.


Sansculottides

The Sansculottides (; also Epagomènes; French "Sans-culottides", "Sanculottides", "jours complémentaires", "jours épagomènes") are holidays following the last month of the year on the French Republican Calendar which was used following the French Revolution from approximately 1793 to 1805.
The Sansculottides, named after the sans-culottes, append the twelve, 30-day months of the Republican Calendar with five complementary days in a common year or six complementary days in a leap year so that the calendar year would approximately match the tropical year. They follow the last day of Fructidor, the last month of the year, and precede the first day of Vendémiaire.
The Sansculottides belong to the summer quarter. They begin on 17 or 18 September and approximately end on the autumn equinox, on 22 or 23 September on the Gregorian calendar.
History.
In the decree of 5 October 1793 ("le 14 du 1er mois de l'an II"; later: "le 14 Vendémiaire de l'an II") by the National Convention, the days following the last month of the year were named "jours complémentaires" and numbered serially. Only the leap day ("jour intercalaire") received a name:
The other days, decades, and months were also serially numbered.
On 24 October ("le 3 du 2e mois"; later: "le 3 Brumaire") of the same year, the poet Philippe-François-Nazaire Fabre, known as Fabre d'Églantine, made public his dislike of this naming convention ("le premier jour de la première décade du premier mois de la première année"). He suggested proper names for the months, the days of the months, and the days of the decades. For the "jours complémentaires", he introduced the name "Sansculottides". The individual days should have the following names:
According to the proposal by Fabre d'Églantine:
On 24 November 1793 these proposals were accepted with slight modifications. It was decided that the name should be written "fêtes Sansculotides" (one 't'). The alternate spellings "Sans-culotides" and "Sans-culottides" were also used. The "fête des actions" was shifted to the first place and named "fête de la vertu". The "fête des récompenses" went to the last place and the leap year day regained its old name:
On 24 August 1795 ("le 7 Fructidor de l'an III"), the Sansculottides were renamed again to "jours complémentaires" (Complementary Days). The "fête du travail" was also known as the "fête du labour". The "fête de l'opinion" was also termed "fête de l'option" (Celebration of Choice) or "fête de la raison" (Celebration of Reason).
The Basque translation of the calendar for 1799 simply names the "bethagail-egunak" as "bethagail-legun", "bethagail-bigun"... ("complementary primidi", "complementary duodi"...).


Red Buttes Observatory

Red Buttes Observatory (RBO) is an astronomical observatory owned and operated by University of Wyoming. It is located south of Laramie, Wyoming (USA) and was founded in 1994. The observatory houses a telescope built by DFM Engineering. There are two instruments available: a 1024x1024 imaging camera, and a near-infrared camera. A second, smaller telescope built by Orion is mounted on the main telescope. Research at the observatory has included monitoring Cepheid variable stars and follow-up observation of gamma-ray bursts.


May 2069 lunar eclipse

A total lunar eclipse will take place on May 6, 2069. The eclipse will be a dark one with the southern tip of the moon passing through the center of the Earth's shadow. This is the first central eclipse of Saros series 132.
It is the first of two total lunar eclipses in 2069, the second occurring at the descending node of the moon's orbit will be on October 30th which will also be a central total eclipse.
Visibility.
The eclipse will be visible after sunset over Australia and begin before sunset over far eastern Asia, and be seen in the predawn hours over western North and South America.
The moon will also occult the bright star Alpha Librae as seen from the southern hemisphere a few hours before greatest eclipse.
Related lunar eclipses.
Lunar eclipses are related by many different eclipse cycles. The Saros cycle (18 years and 10 days) repeats the most consistently due three coinciding periods, and continue over 70 events (1200+ years). Eclipses are identified by a Saros number and a member index within each series.
The lunar year (354 days) and Metonic cycles (19 years) are short period last only 8 to 10 events. The Metonic cycle is equal to one Saros cycle plus one lunar year, and so the two series progress in parallel.
The Inex cycle (29 years minus 20 days) can last tens of thousands of years, so long that long perturbations in the moon's path must be taken into account for prediction. Also the eclipse qualities are less inconsistent because the moon is at different significantly positions in its elliptical orbit in sequential events. Similarly for the shorter Tritos cycle (10 years and 31 days), repeats less consistently for the same reason.
Lunar year series.
This eclipse is the third of four lunar year eclipses occurring at the moon's ascending node.
The lunar year series repeats after 12 lunations or 354 days (Shifting back about 10 days in sequential years). Because of the date shift, the Earth's shadow will be about 11 degrees west in sequential events.
Half-Saros cycle.
A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros). This lunar eclipse is related to two total solar eclipses of Solar Saros 139.


Shuangjiang (solar term)

The traditional Chinese calendar divides a year into 24 solar terms (节气/節氣). Shuāngjiàng, "Sōkō", "Sanggang", or "Sương giáng" () is the 18th solar term. It begins when the Sun reaches the celestial longitude of 210° and ends when it reaches the longitude of 225°. It more often refers in particular to the day when the Sun is exactly at the celestial longitude of 210°. In the Gregorian calendar, it usually begins around October 23 and ends around November 7.


Robert Yerburgh

Robert Armstrong Yerburgh, (17 January 1853 – 18 December 1916), was a British barrister and Conservative politician.
Early life.
Yerburgh was the son of the Reverend Richard Yerburgh and Susan Higgin and had ten full brothers and sisters: Richard Eustre, Susan Edith, John Eardley, Oswald, Mary Florence, Edmond Rochfort, Rachel, Harry Beauchamp, Lucy Isabel, and Charlotte Elizabeth. By his father's second marriage in 1863 he had two half-sisters, Annie Constance and Mabel Stanley. He was educated at Rossall School, Harrow School, and University College, Oxford.
Career.
After Oxford, Yerburgh was called to the bar. In 1886 he was elected to the House of Commons for Chester, standing for the Unionists, a seat he lost in 1906, but he was elected again in 1910. He was intended for a peerage in 1916 but died in December of that year, before the patent had been completed, aged 63. He was also a Deputy Lieutenant for Lancashire and a Justice of the Peace for Kirkcudbrightshire.
Private life.
In 1888 Yerburgh married Elma Amy, a daughter of Daniel Thwaites, and the couple lived at Billinge Scar, near Blackburn, before moving to Woodfold Hall. They had two sons. Their eldest son, Robert, also became a Conservative politician and was elevated to the peerage as Baron Alvingham in 1929. Elma Amy Yerburgh died in 1946.


October 2005 lunar eclipse

A partial lunar eclipse took place on October 17, 2005, the second of two lunar eclipses in 2005. A tiny bite out of the Moon may have been visible at maximum, though just 6% of the Moon was shadowed in a partial eclipse which lasted for 56 minutes exactly and was visible over east Asia, Australasia, and most of North America. A shading across the moon from the Earth's penumbral shadow should have been visible at maximum eclipse.
The tables below contain detailed predictions and additional information on the Partial Lunar Eclipse of 17 October 2005..
Eclipse Characteristics.
Penumbral Magnitude: 1.05856
Umbral Magnitude: 0.06256
Gamma: 0.97960
Saros Series: 146th (10 of 72)
Opposition Times.
Greatest Eclipse: 17 Oct 2005 12:03:31:8 UTC (12:04:26.6 TD)
Ecliptic Opposition: 17 Oct 2005 12:13:38.2 UTC (12:14:43.0 TD)
Equatorial Opposition: 17 Oct 2005 12:57:19.6 UTC (12:58:24.5 TD)
Geocentric Coordinates of Sun and Moon.
Sun right ascension: 13.49
Sun declination: -9.4
Sun diameter: 1926.2 arcseconds
Moon right ascension: 1.47
Moon declination: 10.3
Moon diameter: 1933.8 arcseconds
Earth's shadow right ascension: 1.49
Earth's shadow declination: 9.4
Geocentric Libration of Moon.
Latitude: 4.5 degrees north
Longitude: 1.3 degrees west
Direction: 339.8 (NNW)
Visibility.
It was visible from Southeast Asia, the Pacific, Australia and New Zealand after sunset, and in the western side of North America before sunrise.
<BR>A simulated view of the earth from the center of the moon at maximum eclipse.
Relation to other eclipses.
Lunar year series.
It is the last of four lunar year cycles, repeating every 354 days.
Metonic series.
This eclipse is the last of four Metonic cycle lunar eclipses on the same date, October 17–18, each separated by 19 years:
Half-Saros cycle.
A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros). This lunar eclipse is related to two partial solar eclipses of Solar Saros 153.


Beta Pictoris moving group

The Beta Pictoris Moving Group is a young moving group of stars located relatively near Earth. A moving group, in astronomy, is a group of stars that share a common motion through space as well as a common origin. This moving group is named for Beta Pictoris.
The Beta Pictoris Moving Group is an important object for astronomical study as it is the closest youthful group of stars to the Earth. The star Beta Pictoris is known to have a large disk of gas and dust, possibly a protoplanetary disk. There is also evidence of a young gas giant planet around the star. A free-floating planet has also been found in the moving group, PSO J318.5-22. The age and distance of the group makes it a candidate for directly imaging extrasolar planets.
Constituents.
The Beta Pictoris Moving Group consists of 17 stellar systems, comprising a total of 28 individual component stars, including identified brown dwarfs. The core of the group is located some 115 light-years from Earth, and has an average estimated age of between 20 and 26 million years.
The majority of the group is made up of cool, dim K and M class stars. Most are not visible to the naked eye. The members that are visible to the naked eye are:
The group covers a region of space for the most part visible only in the Southern Hemisphere, and lies in the constellations Eridanus, Lepus, Pictor, Scorpius, Fornax, Triangulum Australe and Telescopium.
Discovery.
An early estimated age for the star Beta Pictoris at about 10 million years proved problematic due to the star's apparent isolation in space. According to current theory regarding stellar evolution, extremely young stars of this age should be located near other young stars that formed from the same region in space. It is not until significantly later that gravitational interactions with other stars causes stellar 'siblings' to disperse.
In 1999 the situation was resolved by the discovery of a pair of dim red dwarf stars that were found to have a similar velocity and age to β Pictoris, lending credence to the estimated age of the star.
Further work published in 2001 identified a total of 17 stellar systems with a similar motion and age as the Beta Pictoris moving group, named for the primary member of the association.
Origin.
The movements of the group were tracked to the positions they occupied 11.5Myr ago, where they occupied a space 3 times smaller than their current distribution (24pc, versus 72pc today) situated in between two regions of the Scorpius-Centaurus OB star group, and it was suggested that they originated there when a supernova from either OB region of Scorpius-Centaurus OB would have been close enough to trigger stellar formation.


Alexander Adie

Alexander James Adie FRSE MWS (1775, Edinburgh – 4 December 1858, Edinburgh) was a Scottish maker of medical instruments, optician and meteorologist. He was the inventor of the sympiesometer, patented in 1818.
Life.
He was born the son of John Adie.
He was apprenticed in 1789 to his maternal uncle John Miller a mathematical instrument maker on Parliament Close, off the Royal Mile close to St Giles Cathedral in Edinburgh. In 1800 Adie was working for Miller at 38 South Bridge and the business was described as an optician. Around 1805 went into business together as "Miller and Adie, Opticians" (also serving as mathematical instrument makers, but this was in much less demand) and had a shop at 15 Nicholson Street in the South Side which continued until 1822.
After Miller died Adie opened his own shop at 58 Princes Street close to the Royal Scottish Academy.
Adie supplied lenses to Joseph Hooker, Charles Darwin and Sir David Brewster and was optician to William IV and to Queen Victoria. Adie invented the sympiesometer or marine barometer and had a small observatory erected long before there was a public observatory in Edinburgh. He was elected as Fellow of the Royal Society of Edinburgh on 25 January 1819, upon the proposal of Lord Francis Gray, Sir David Brewster and James Russell.
Adie lived at 10 Regent Terrace, Edinburgh, from 1832 to 1838. His son John Adie FRSE joined his firm around 1840 to create Adie & Son based at 50 Princes Street.
He died at Caanan Lodge, in the Morningside district of Edinburgh (now demolished) in December 1858, and was interred in Greyfriars Kirkyard. The grave lies to the south-west of the church, just to the north-east of the Adam mausoleum.
His daughter married the astronomer Thomas Henderson (1798–1844) who would certainly have met through the instrument making. Henderson is buried with Adie but is not listed on the memorial.
Alexander James Adie (railway engineer).
Adie's son was born at 11 Lothian Street in Edinburgh's South Side on 16 December 1808 and also named Alexander James Adie after his father.
He studied at the High School in Edinburgh and then Edinburgh University before training as a civil engineer under James Jardine.
In 1836 he became Resident Engineer on the Bolton, Chorley and Preston Railway. In 1863 he became Manager of the Edinburgh and Glasgow Railway.
In February 1846 he followed in his father's footsteps and was elected a Fellow of the Royal Society of Edinburgh his proposer being James David Forbes. At this time he was living at 50 Princes Street above his father's shop.
In later life he lived at 7 St Andrews Square in Edinburgh (now demolished).
He died at his home, Rockville near Linlithgow, where he had retired to, on 3 April 1879. He is buried on the south side of St Michael's Church in Linlithgow.