Seth Carlo Chandler

Seth Carlo Chandler, Jr. (September 16, 1846 – December 31, 1913) was an American astronomer.
He was born in Boston, Massachusetts to Seth Carlo and Mary (née Cheever) Chandler. During his last year in high school he performed mathematical computations for Benjamin Peirce, of the Harvard College Observatory.
After graduating, he became the assistant of Benjamin A. Gould. Gould was director of the Longitude Department of the U.S. Coast Survey program, a geodetic survey program. When Gould left to become director of the national observatory in Argentina, Chandler also left and became an actuary. However, he continued to work in astronomy as an amateur affiliated with Harvard College Observatory.
Chandler is best remembered for his research on what is today known as the Chandler wobble. His research on this spanned nearly three decades.
Chandler also made contributions to other areas of astronomy, including variable stars. He independently co-discovered the nova T Coronae Borealis, improved the estimate of the constant of aberration, and computed the orbital parameters of asteroids and comets.
Chandler was awarded the Gold Medal of the Royal Astronomical Society in 1896 and the James Craig Watson Medal in 1894.
The crater Chandler on the Moon is named after him.


Jessica Werk

Jessica K. Werk is an American astronomer and an associate professor in the Department of Astronomy at the University of Washington Her work includes the study of intergalactic and interstellar media. Werk was a Hubble fellow at the University of California, Santa Cruz from 2013 to 2016, and won the $65,000 Sloan Fellowship in 2018. Her research focuses on the role of gas in the formation and evolution of galaxies and the intergalactic medium, primarily through spectroscopic observations in the optical and ultraviolet.
Early life and education.
Jessica Werk was born in Hartford, Connecticut in 1981. She received a Bachelor of Arts degree in Physics and Astronomy with high honors at Wesleyan University in 2003, and a PhD in Astronomy at the University of Michigan in 2010. Her PhD focused on HII regions in the outskirts of normal spiral galaxies.
Academic career.
Werk was a National Science Foundation graduate student fellow at University of Michigan from 2006-2009, a visiting scholar at Columbia University from 2008-2010, and a postgraduate research fellow at University of California, Santa Cruz from 2010-2013. Since 2016, she has held the position of Assistant Professor at the University of Washington.
Research.
Werk studies the largely unexplored extended gaseous components of galaxies using both ground and space-based spectral observations in the optical and ultraviolet regimes. Her work defines observational constraints for cosmological simulations, and focuses on the dark-matter halo and disk-halo interface. She aims to understand the cosmic baryon cycle that traces how baryons pass from stellar interiors through the interstellar medium and intergalactic medium.
She has worked on developing the Hubble COS-Halos Survey, which uses the Hubble Space Telescope Cosmic Origins Spectrograph (COS), alongside ground-based observations, to study the prominent role gas plays in driving galactic evolution. Results from the COS-Halos Survey are presented in "The COS-Halos Survey: An Empirical Description of Metal-line Absorption in the Low-redshift Circumgalactic Medium" by Werk et al., and the paper "The COS-Halos Survey: Physical Conditions and Baryonic Mass in the Low-redshift Circumgalactic Medium" by Werk et al. The latter work established that there are likely more baryons in the extended halos of galaxies than there are in the galaxy disks. This conclusion highlights the importance of studying the physical state and complex history of what has become known as the circumgalactic medium.


Max Planck Institute for Astrophysics

The Max Planck Institute for Astrophysics (MPA) is a research institute located in Garching, just north of Munich, Bavaria, Germany. It is one of many scientific research institutes belonging to the Max Planck Society.
The MPA is widely considered to be one of the leading institutions in the world for theoretical astrophysics research. According to Thomson Reuters, from 1999-2009 the Max Planck Society as a whole published more papers and accumulated more citations in the fields of physics and space science than any other research organization in the world.
History.
The Max Planck Society was founded on 26 February 1948. It effectively replaced the Kaiser Wilhelm Society for the Advancement of Science, which was dissolved after World War II. The society is named after Max Planck, one of the founders of quantum theory.
The MPA was founded as the Max Planck Institute for Physics and Astrophysics in 1958 and split into the Max Planck Institute for Astrophysics and the Max Planck Institute for Physics in 1991. In 1995, the numerical relativity group moved to the Max Planck Institute for Gravitational Physics.
Organization.
The MPA is one of several Max Planck Institutes that specialize in astronomy and astrophysics. Others are the Max Planck Institute for Extraterrestrial Physics in Garching (located next-door to the MPA), the Max Planck Institute for Astronomy in Heidelberg, the Max Planck Institute for Radio Astronomy in Bonn, the Max Planck Institute for Solar System Research in Göttingen, and the Max Planck Institute for Gravitational Physics (a.k.a. Albert Einstein Institute) in Golm.
The institute is located next-door to the MPI for Extraterrestrial Physics, as well as the headquarters of the European Southern Observatory. It also enjoys close working relationships with the Ludwig Maximilian University of Munich and Technical University Munich.
At any given time, the institute employs approximately 50 scientists, instructs over 30 PhD students, and hosts about 20 visiting scientists (some 60 visitors stay for longer than 2 weeks in any given year).
As of 2021, the four directors of the MPA are Selma de Mink, Guinevere Kauffmann, Eiichiro Komatsu, and Volker Springel.
Previous directors include Ludwig Biermann (1958 – 75), Rudolf Kippenhahn (1975 – 91), Simon White (1994 – 2019), Rashid Sunyeav (1995 – 2018), Wolfgang Hillebrandt (1997 – 2009) and Martin Asplund (2007 – 2011).
Science.
Focusing on theoretical investigations, the MPA covers a wide range of topics in astrophysics. These include:
Public outreach.
The MPA works to explain astrophysical concepts and disseminate its findings to the public. These activities include popular science articles written by MPA scientists, events hosting school groups, events open to the general public, and monthly research highlights written for a general audience.
Graduate program.
The International Max Planck Research School (IMPRS) for Astrophysics is a graduate program offering a PhD in astrophysics. The school is a cooperation with the Ludwig Maximilian University of Munich and Technical University Munich.


Yushui (solar term)

The traditional Chinese calendar divides a year into 24 solar terms. Yǔshuǐ, "Usui", "Usu", or "Vũ thủy" is the 2nd solar term. It begins when the Sun reaches the celestial longitude of 330° and ends when it reaches the longitude of 345°. It more often refers in particular to the day when the Sun is exactly at the celestial longitude of 330°. In Gregorian calendar, it usually begins around 18 February (19 February East Asia time) and ends around 5 March.
Pentads.
Each solar term can be divided into three pentads (候). They are first pentad (初候), second pentad (次候) and last pentad (末候). Pentads in Yushui including:


Atmosphere of Titan

The atmosphere of Titan is the dense layer of gases surrounding Titan, the largest moon of Saturn. It is the only thick atmosphere of a natural satellite in the Solar System. Titan's lower atmosphere is primarily composed of nitrogen (94.2%), methane (5.65%), and hydrogen (0.099%). There are trace amounts of other hydrocarbons, such as ethane, diacetylene, methylacetylene, acetylene, propane, PAHs and of other gases, such as cyanoacetylene, hydrogen cyanide, carbon dioxide, carbon monoxide, cyanogen, acetonitrile, argon and helium. The isotopic study of nitrogen isotopes ratio also suggest acetonitrile may be present in quantities exceeding hydrogen cyanide and cyanoacetylene. The surface pressure is about 50% higher than on Earth at 1.5 bars (147 kPa) which is near the triple point of methane and allows there to be gaseous methane in the atmosphere and liquid methane on the surface. The orange color as seen from space is produced by other more complex chemicals in small quantities, possibly tholins, tar-like organic precipitates.
Observational history.
The presence of a significant atmosphere was first suspected by Spanish astronomer Josep Comas i Solà, who observed distinct limb darkening on Titan in 1903, and confirmed by Gerard P. Kuiper in 1944 using a spectroscopic technique that yielded an estimate of an atmospheric partial pressure of methane of the order of 100 millibars (10 kPa). Subsequent observations in the 1970s showed that Kuiper's figures had been significantly underestimated; methane abundances in Titan's atmosphere were ten times higher, and the surface pressure was at least double what he had predicted. The high surface pressure meant that methane could only form a small fraction of Titan's atmosphere. In 1980, "Voyager 1" made the first detailed observations of Titan's atmosphere, revealing that its surface pressure was higher than Earth's, at 1.5 bars (about 1.48 times that of Earth's).
The joint NASA/ESA "Cassini-Huygens" mission provided a wealth of information about Titan, and the Saturn system in general, since entering orbit on July 1, 2004. It was determined that Titan's atmospheric isotopic abundances were evidence that the abundant nitrogen in the atmosphere came from materials in the Oort cloud, associated with comets, and not from the materials that formed Saturn in earlier times. It was determined that complex organic chemicals could arise on Titan, including polycyclic aromatic hydrocarbons, propylene, and methane.
The "Dragonfly" mission by NASA is planning to land a large aerial vehicle on Titan in 2034. The mission will study Titan's habitability and prebiotic chemistry at various locations. The drone-like aircraft will perform measurements of geologic processes, and surface and atmospheric composition.
Overview.
Observations from the "Voyager" space probes have shown that the Titanean atmosphere is denser than Earth's, with a surface pressure about 1.48 times that of Earth's. Titan's atmosphere is about 1.19 times as massive as Earth's overall, or about 7.3 times more massive on a per surface area basis. It supports opaque haze layers that block most visible light from the Sun and other sources and renders Titan's surface features obscure. The atmosphere is so thick and the gravity so low that humans could fly through it by flapping "wings" attached to their arms. Titan's lower gravity means that its atmosphere is far more extended than Earth's; even at a distance of 975 km, the "Cassini" spacecraft had to make adjustments to maintain a stable orbit against atmospheric drag. The atmosphere of Titan is opaque at many wavelengths and a complete reflectance spectrum of the surface is impossible to acquire from the outside. It was not until the arrival of "Cassini–Huygens" in 2004 that the first direct images of Titan's surface were obtained. The "Huygens" probe was unable to detect the direction of the Sun during its descent, and although it was able to take images from the surface, the "Huygens" team likened the process to "taking pictures of an asphalt parking lot at dusk".
Vertical structure.
Titan's vertical atmospheric structure is similar to Earth. They both have a troposphere, stratosphere, mesosphere, and thermosphere. However, Titan's lower surface gravity creates a more extended atmosphere, with scale heights of 15–50 km (9–31 mi) in comparison to 5–8 km (3.1-5 mi) on Earth. Voyager data, combined with data from "Huygens" and radiative-convective models provide increased understanding of Titan's atmospheric structure.
Atmospheric composition and chemistry.
Titan's atmospheric chemistry is diverse and complex. Each layer of the atmosphere has unique chemical interactions occurring within that are then interacting with other sub layers in the atmosphere. For instance, the hydrocarbons are thought to form in Titan's upper atmosphere in reactions resulting from the breakup of methane by the Sun's ultraviolet light, producing a thick orange smog. The table below highlights the production and loss mechanisms of the most abundant photochemically produced molecules in Titan's atmosphere.
Magnetic field.
Titan has no magnetic field, although studies in 2008 showed that Titan retains remnants of Saturn's magnetic field on the brief occasions when it passes outside Saturn's magnetosphere and is directly exposed to the solar wind. This may ionize and carry away some molecules from the top of the atmosphere. Titan's internal magnetic field is negligible, and perhaps even nonexistent. Its orbital distance of 20.3 Saturn radii does place it within Saturn's magnetosphere occasionally. However, the difference between Saturn's rotational period (10.7 hours) and Titan's orbital period (15.95 days) causes a relative speed of about between the Saturn's magnetized plasma and Titan. That can actually intensify reactions causing atmospheric loss, instead of guarding the atmosphere from the solar wind.
Chemistry of the ionosphere.
In November 2007, scientists uncovered evidence of negative ions with roughly 13 800 times the mass of hydrogen in Titan's ionosphere, which are thought to fall into the lower regions to form the orange haze which obscures Titan's surface. The smaller negative ions have been identified as linear carbon chain anions with larger molecules displaying evidence of more complex structures, possibly derived from benzene. These negative ions appear to play a key role in the formation of more complex molecules, which are thought to be tholins, and may form the basis for polycyclic aromatic hydrocarbons, cyanopolyynes and their derivatives. Remarkably, negative ions such as these have previously been shown to enhance the production of larger organic molecules in molecular clouds beyond our Solar System, a similarity which highlights the possible wider relevance of Titan's negative ions.
Atmospheric circulation.
There is a pattern of air circulation found flowing in the direction of Titan's rotation, from west to east. In addition, seasonal variation in the atmospheric circulation has also been detected. Observations by "Cassini" of the atmosphere made in 2004 also suggest that Titan is a "super rotator", like Venus, with an atmosphere that rotates much faster than its surface. The atmospheric circulation is explained by a big Hadley circulation that is occurring from pole to pole.
Methane cycle.
Energy from the Sun should have converted all traces of methane in Titan's atmosphere into more complex hydrocarbons within 50 million years — a short time compared to the age of the Solar System. This suggests that methane must be somehow replenished by a reservoir on or within Titan itself. Most of the methane on Titan is in the atmosphere. Methane is transported through the cold trap at the tropopause. Therefore the circulation of methane in the atmosphere influences the radiation balance and chemistry of other layers in the atmosphere. If there is a reservoir of methane on Titan, the cycle would only be stable over geologic timescales. Evidence that Titan's atmosphere contains over a thousand times more methane than carbon monoxide would appear to rule out significant contributions from cometary impacts, because comets are composed of more carbon monoxide than methane. That Titan might have accreted an atmosphere from the early Saturnian nebula at the time of formation also seems unlikely; in such a case, it ought to have atmospheric abundances similar to the solar nebula, including hydrogen and neon. Many astronomers have suggested that the ultimate origin for the methane in Titan's atmosphere is from within Titan itself, released via eruptions from cryovolcanoes.
Daytime and Twilight (sunrise/sunset) Skies.
Sky brightness and viewing conditions are expected to be quite different from Earth and Mars due to Titan's farther distance from the Sun (~10 AU) and complex haze layers in its atmosphere. The sky brightness model videos show what a typical sunny day may look like standing on the surface of Titan based on radiative transfer models.
For astronauts who see with visible light, the daytime sky has a distinctly dark orange color and appears uniform in all directions due to significant Mie scattering from the many high-altitude haze layers. The daytime sky is calculated to be ~100-1000 times dimmer than an afternoon on Earth, which is similar to the viewing conditions of a thick smog or dense fire smoke. The sunsets on Titan are expected to be "underwhelming events", where the Sun disappears about half-way up in the sky (~50° above the horizon) with no distinct change in color. After that, the sky will slowly darken until it reaches night. However, the surface is expected to remain as bright as the full Moon up to 1 Earth day after sunset.
In near-infrared light, the sunsets resemble a or dusty desert sunset. Mie scattering has a weaker influence at longer infrared wavelengths, allowing for more colorful and variable sky conditions. During the daytime, the Sun has a noticeable solar corona that transitions color from white to "red" over the afternoon. The afternoon sky brightness is ~100 times dimmer than Earth. As evening time approaches, the Sun is expected to disappear fairly close to the horizon. Titan's atmospheric optical depth is the lowest at 5 microns. So, the Sun at 5 microns may even be visible when it is below the horizon due to atmospheric refraction. Similar to images to from Mars rovers, a fan-like corona is seen to develop above the Sun due to scattering from haze or dust at high-altitudes.
In regards to Saturn, the planet is nearly fixed in its position in the sky because Titan's orbit is tidally locked around Saturn. However, there is a small 3° east-to-west motion over a Titan year due to the orbital eccentricity, similar to the analemma on Earth. Sunlight reflected off of Saturn, Saturnshine, is about 1000 times weaker than solar insolation on the surface of Titan. Even though Saturn appears several times bigger in the sky than the Moon in Earth's sky, the outline of Saturn is masked out by the brighter Sun during the daytime. Saturn may only become discernible at night, but only at a wavelength of 5 microns. This is due to two factors: the small optical depth of Titan's atmosphere at 5 microns and the strong 5 μm emissions from Saturn's night side. In visible light, Saturn will make the sky slightly brighter, similar to an overcast night with a full moon on Earth. Saturn's rings are hidden from view owing to the alignment of Titan's orbital plane and the plane of the rings. Saturn is expected to show phases, akin to the phases of Venus on Earth, that partially illuminate the surface of Titan at night, except for eclipses.
From outer space, "Cassini" images from near-infrared to UV wavelengths have shown that the twilight periods (sunrise/sunset) are "brighter" than the daytime on Titan. Scientists expect that planetary brightness will weaken going from the day to night side of the planetary body, known as the terminator. This paradoxical observation has not been observed on any other planetary body with a thick atmosphere. The Titanean twilight outshining the dayside is likely due to a combination of Titan's atmosphere extending hundreds of kilometers above the surface and intense forward Mie scattering from the haze. Radiative transfer models have not reproduced this effect.
Atmospheric evolution.
The persistence of a dense atmosphere on Titan has been enigmatic as the atmospheres of the structurally similar satellites of Jupiter, Ganymede and Callisto, are negligible. Although the disparity is still poorly understood, data from recent missions have provided basic constraints on the evolution of Titan's atmosphere.
Roughly speaking, at the distance of Saturn, solar insolation and solar wind flux are sufficiently low that elements and compounds that are volatile on the terrestrial planets tend to accumulate in all three phases. Titan's surface temperature is also quite low, about 94 K. Consequently, the mass fractions of substances that can become atmospheric constituents are much larger on Titan than on Earth. In fact, current interpretations suggest that only about 50% of Titan's mass is silicates, with the rest consisting primarily of various H2O (water) ices and NH3·H2O (ammonia hydrates). NH3, which may be the original source of Titan's atmospheric N2 (dinitrogen), may constitute as much as 8% of the NH3·H2O mass. Titan is most likely differentiated into layers, where the liquid water layer beneath ice Ih may be rich in NH3.

Tentative constraints are available, with the current loss mostly due to low gravity and solar wind aided by photolysis. The loss of Titan's early atmosphere can be estimated with the 14N–15N isotopic ratio, because the lighter 14N is preferentially lost from the upper atmosphere under photolysis and heating. Because Titan's original 14N–15N ratio is poorly constrained, the early atmosphere may have had more N2 by factors ranging from 1.5 to 100 with certainty only in the lower factor. Because N2 is the primary component (98%) of Titan's atmosphere, the isotopic ratio suggests that much of the atmosphere has been lost over geologic time. Nevertheless, atmospheric pressure on its surface remains nearly 1.5 times that of Earth as it began with a proportionally greater volatile budget than Earth or Mars. It is possible that most of the atmospheric loss was within 50 million years of accretion, from a highly energetic escape of light atoms carrying away a large portion of the atmosphere (hydrodynamic escape). Such an event could be driven by heating and photolysis effects of the early Sun's higher output of X-ray and ultraviolet (XUV) photons.
Because Callisto and Ganymede are structurally similar to Titan, it is unclear why their atmospheres are insignificant relative to Titan's. Nevertheless, the origin of Titan's N2 via geologically ancient photolysis of accreted and degassed NH3, as opposed to degassing of N2 from accretionary clathrates, may be the key to a correct inference. Had N2 been released from clathrates, 36Ar and 38Ar that are inert primordial isotopes of the Solar System should also be present in the atmosphere, but neither has been detected in significant quantities. The insignificant concentration of 36Ar and 38Ar also indicates that the ~40 K temperature required to trap them and N2 in clathrates did not exist in the Saturnian sub-nebula. Instead, the temperature may have been higher than 75 K, limiting even the accumulation of NH3 as hydrates. Temperatures would have been even higher in the Jovian sub-nebula due to the greater gravitational potential energy release, mass, and proximity to the Sun, greatly reducing the NH3 inventory accreted by Callisto and Ganymede. The resulting N2 atmospheres may have been too thin to survive the atmospheric erosion effects that Titan has withstood.
An alternative explanation is that cometary impacts release more energy on Callisto and Ganymede than they do at Titan due to the higher gravitational field of Jupiter. That could erode the atmospheres of Callisto and Ganymede, whereas the cometary material would actually build Titan's atmosphere. However, the 2H–1H (i.e. D–H) ratio of Titan's atmosphere is , nearly 1.5 times lower than that of comets. The difference suggests that cometary material is unlikely to be the major contributor to Titan's atmosphere. Titan's atmosphere also contains over a thousand times more methane than carbon monoxide which supports the idea that cometary material is not a likely contributor since comets are composed of more carbon monoxide than methane.


Keith Mason (scientist)

Keith Mason (born 19 April 1951) was, until 1 November 2011, the Chief Executive of the Science and Technology Facilities Council (STFC) of the United Kingdom. He assumed the post on 1 April 2007 after the merger of the Council for the Central Laboratory of the Research Councils (CCLRC) and the Particle Physics and Astronomy Research Council (PPARC), having previously been chief executive of PPARC.
Early life.
He attended Ysgol John Bright, the John Bright Grammar School. After a farming childhood on the Llyn Peninsula, Mason initially trained as an astronomer, studying for a BSc and PhD in Physics at University College London, and was a candidate astronaut.
Career.
He subsequently worked on X-ray astronomy at UC Berkeley before returning to the UCL Mullard Space Science Laboratory, eventually becoming a professor at UCL and director of the Mullard Laboratory in 2003.


Hermann Goldschmidt

Hermann Mayer Salomon Goldschmidt (June 17, 1802 – August 30 or September 10 1866) was a German-French astronomer and painter who spent much of his life in France. He started out as a painter, but after attending a lecture by the famous French astronomer Urbain Le Verrier turned to astronomy. His discovery of the asteroid Lutetia in 1852 was followed by further findings and by 1861 Goldschmidt had discovered 14 asteroids. He received the Gold Medal of the Royal Astronomical Society in 1861 for having discovered more asteroids than any other person up to that time. He died from complications of diabetes.
Life and work.
Goldschmidt was born in Frankfurt as the son of a Jewish merchant. During a journey to the Netherlands, Goldschmidt visited Dutch picture galleries. The impression of this visit convinced him to become a painter. He studied art in Munich for several years under supervision of such famous painters as Peter von Cornelius and Julius Schnorr von Carolsfeld. To complete his education, in 1836 Goldschmidt went to Paris.
In 1820, Goldschmidt discovered shadow bands in total solar eclipses.
Several lectures on astronomy were planned for the occasion of the lunar eclipse of March 31, 1847. Urbain Le Verrier, discoverer of Neptune, held one in the Sorbonne. By pure chance, Goldshmidt attended this lecture, which awakened his interest in astronomy and led him to pursue it as a career.
Goldschmidt bought a telescope with the diameter of 23 lines () with the money he got from selling two portraits of Galileo he painted during a stay in Florence. Goldschmidt set up the telescope in his apartment on the sixth floor above the Café Procope. Very soon he started updating the Star charts he had with new stars. During this work he observed the same area several times and was able to detect variable stars and moving objects like planets. He discovered his first new planet (today classified as asteroid) on November 15, 1852. Goldschmidt confirmed his observations with the help of François Arago at the Paris Observatory on November 18. Arago suggested the name Lutetium, based on the Latin name of Paris "Lutetia" used during the Roman occupation. The discovery of the new planet was published on November 23.
In subsequent years, Goldschmidt bought larger telescopes, one with 30 lines diameter. Despite the limited observational capabilities of his instrument, which was inferior to those of most of his competitors, by May 1856 Goldschmidt had discovered four more asteroids. His next telescope was one with the diameter of . This technical improvement enabled him to discover nine asteroids between May 1857 and May 1861. During that period, the Academy of Science awarded Goldschmidt the astronomical prize medal several times, and he was made a chevalier of the Légion d'honneur in 1857. By the time of his final discovery in May 1861, the Royal Astronomical Society had awarded him the Gold Medal of the Royal Astronomical Society for the discovery of 13 asteroids. At that point, the second most successful astronomers John Russell Hind and Robert Luther had each discovered 10.
Goldschmidt combined his abilities as a painter with his love for astronomy as exemplified by his paintings of the Great Comet of 1858 and of the solar eclipse he observed in Spain July 1860. In April 1861, he announced the discovery of a ninth moon of Saturn between Titan and Hyperion, which he named "Chiron". However, he was mistaken: this moon did not exist; today, "Chiron" is the name of an entirely different object, the unusual asteroid/comet 2060 Chiron. His updated star charts and the discovery of several variable stars were also appreciated by his colleagues.
Goldschmidt was never employed at the Paris Observatory and therefore his income was insecure. However, in 1862 he was awarded a pension of 1500 francs. Because of his diabetes, Goldschmidt moved to Fontainebleau, but his condition did not improve. He stayed in Fontainebleau for three years and died there on April 26, 1866.
Namesakes.
The lunar crater "Goldschmidt" is named after him. The crater is located in the northern polar region.
The outer main-belt asteroid 1614 Goldschmidt, discovered by French astronomer Alfred Schmitt in 1952, was named in his memory.
Prizes and Awards.
Goldschmidt was awarded the Lalande Prize seven times (1852, 1854, 1855, 1857, 1858, 1860, 1861).
He was awarded chevalier of the Légion d'honneur in 1857.
In 1861, received Gold Medal of the Royal Astronomical Society for the discovery of 13 asteroids (at that time).
In 1869, a commemorative medal honoring the discovery of the 100th asteroid shows the profiles of John Russel Hind, Hermann Goldschmidt and Robert Luther.


William Richardson (bishop)

William Moore Richardson (1844 – 6 March 1915) was the Anglican Bishop of Zanzibar from 1895 until 1901.
He was born in 1844,educated at Rossall School and Merton College, Oxford and ordained in 1869. He held incumbencies at Wolvercote and Ponteland before his elevation to the Episcopate. On his return from Africa he was Warden of the Community of St Thomas the Martyr in Oxford until his retirement in 1910. He died on 6 March 1915.


Severus Sebokht

Severus Sebokht (), also Seboukt of Nisibis, was a Syrian scholar and bishop who was born in Nisibis, Syria in 575 and died in 667.
Although little is known about his early life, he was one of the leading figures in Syria in the 7th century. He taught at the Theological School of Nisibis. In 612, he left the post because of a doctrinal dispute with the Syriac Church of the East. He was a member of the Syriac Orthodox Church. He was a resident of the monastery of Qenneshre, which was situated near the banks of the Euphrates. His student Jacob of Edessa (d. 708), the major representative of “Christian Hellenism".
He was a teacher of the philosophy of Aristotle. In 638, he wrote a major treatise on syllogisms. He translated into Syriac the commentaries on Aristotle of Paul the Persian.
He was perhaps the first Syrian to mention the Indian number system.
He wrote a major treatise on the Astrolabe. His treatise contained 25 chapters and provided detailed explanations of the measurements of the movements of heavenly bodies.


Alhazen (crater)

Alhazen is a lunar impact crater that lies near the eastern limb of the Moon's near side. Just to the south-southeast is the crater Hansen, and to the west is the Mare Crisium. The rim of Alhazen is nearly circular, but appears highly oblong when viewed from the Earth due to foreshortening. The inner walls and the crater floor are rugged and irregular. A low ridge joins the south rim of Alhazen with the nearby Hansen. The crater is named after the Arab Muslim scientist, Ibn al-Haytham.
Satellite craters.
By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Alhazen.


Sternberg Astronomical Institute

The Sternberg Astronomical Institute (Государственный астрономический институт имени Штернберга in Russian), also known as GAISh (ГАИШ), is a research institution in Moscow, Russia, a division of Moscow State University. The institute is named after astronomer Pavel Karlovich Shternberg. It was founded in 1931, on the site of the observatory established by the university in 1831.
The main-belt asteroid 14789 GAISH, discovered by Lyudmila Chernykh at the Crimean Astrophysical Observatory in 1969, was named in its honour. The official naming citation was published on 6 January 2007 ().


Sarah Lee Lippincott

Sarah Lee Lippincott (October 26, 1920 – February 28, 2019), also known as Sarah Lee Lippincott Zimmerman, was an American astronomer. She was professor emerita of astronomy at Swarthmore College and director emerita of the college's Sproul Observatory.
 She was a pioneer in the use of astrometry to determine the character of binary stars and search for extrasolar planets.
Education.
Lippincott received a bachelor of arts degree from the University of Pennsylvania in 1941 and an master of arts from Swarthmore College in 1942.
Life.
Lippincott was born in 1920 and attended college at the University of Pennsylvania College for Women in the 1940s, where she played on the women's basketball team.
After graduation from the University of Pennsylvania, Lippincott attended Swarthmore College, where she worked closely with Peter van de Kamp on many astrometry projects between 1945 and his retirement in 1972, when she became observatory director. She wrote his obituary when he died in 1995.
She was the third wife of the late Dave Garroway, the founding host of NBC's "Today" show. Garroway had an active interest in astronomy, and they met on a tour of observatories in the Soviet Union that she was hosting. After Garroway's death by suicide at their home in 1982, she helped establish the Dave Garroway Laboratory for the Study of Depression at the University of Pennsylvania.
She conducted numerous astrometric studies of nearby stars with van de Kamp in the search for extrasolar planets. She reported the discovery of several objects of substellar mass and proposed a 0.01 solar-mass planetary companion to the star "Lalande 21185" in 1951. The same proposal of planetary objects was made for a number of other stars, as well. Claims for the smaller planetary objects were never confirmed and gradually have become discredited. However, she was quite successful in using the same techniques for characterizing many binary star systems. Her 1951 calculations of the orbit of the difficult astronomical binary star system "Ross 614" were used to successfully find and image the system's secondary star. These calculations were used by Walter Baade to find and optically resolve this binary system for the first time using the then new Hale Telescope at the Palomar Observatory in California.
She is listed as professor emerita of astronomy and director emerita of the Sproul Observatory in the 2010 Swarthmore college catalog. She last published astronomy research papers in 1983. In 2009, she attended the dedication ceremony for the new Peter van de Kamp observatory at Swarthmore College.
Lippincott died on February 28, 2019, in Kendal Longwood.
Honors and awards.
In 1966, she received the Kappa Kappa Gamma Alumnae Achievement Award.
In 1973, she was awarded an honorary doctor of science by Villanova University.
In 1976, she was elected to the Distinguished Daughters of Pennsylvania (as Mrs. Christian Zimmerman).
Sample publications.
Books.
Lippincott authored two books, with coauthors:
Papers.
Lippincott published over one hundred papers in her career. These are two typical examples:


Solar eclipse of January 26, 2047

A partial solar eclipse will occur on Saturday, January 26, 2047. 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. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.
Images.
Animated path


Meteor procession

A meteor procession occurs when an Earth-grazing meteor breaks apart, and the fragments travel across the sky in the same path. According to physicist Donald Olson, only a few occurrences are known, including:


Yellow hypergiant

A yellow hypergiant (YHG) is a massive star with an extended atmosphere, a spectral class from A to K, and, starting with an initial mass of about 20–60 solar masses, has lost as much as half that mass. They are amongst the most visually luminous stars, with absolute magnitude (MV) around −9, but also one of the rarest, with just 15 known in the Milky Way and six of those in just a single cluster. They are sometimes referred to as cool hypergiants in comparison with O- and B-type stars, and sometimes as warm hypergiants in comparison with red supergiants.
Classification.
The term "hypergiant" was used as early as 1929, but not for the stars currently known as hypergiants. Hypergiants are defined by their '0' luminosity class, and are higher in luminosity than the brightest supergiants of class Ia, although they were not referred to as hypergiants until the late 1970s. Another criterion for hypergiants was also suggested in 1979 for some other highly luminous mass-losing hot stars, but was not applied to cooler stars. In 1991, Rho Cassiopeiae was the first to be described as a yellow hypergiant, likely becoming grouped as a new class of luminous stars during discussions at the "Solar physics and astrophysics at interferometric resolution" workshop in 1992.
Definitions of the term hypergiant remains vague, and although luminosity class 0 is for hypergiants, they are more commonly designated by the alternative luminosity classes Ia-0 and Ia+. Their great stellar luminosities are determined from various spectral features, which are sensitive to surface gravity, such as Hβ line widths in hot stars or a strong Balmer discontinuity in cooler stars. Lower surface gravity often indicates larger stars, and hence, higher luminosities. In cooler stars, the strength of observed oxygen lines, such as O I at 777.4 nm., can be used to calibrate directly against stellar luminosity.
One astrophysical method used to definitively identify yellow hypergiants is the so-called "Keenan-Smolinski" criterion. Here all absorption lines should be strongly broadened, beyond those expected of bright supergiant stars, and also show strong evidence of significant mass loss. Furthermore, at least one broadened Hα component should also be present. They may also display very complex Hα profiles, typically having strong emission lines combined with absorption lines.
The terminology of yellow hypergiants is further complicated by referring to them as either cool hypergiants or warm hypergiants, depending on the context. Cool hypergiants refers to all sufficiently luminous and unstable stars cooler than blue hypergiants and LBVs, including both yellow and red hypergiants. The term warm hypergiants has been used for highly luminous class A and F stars in M31 and M33 that are not LBVs, as well as more generally for yellow hypergiants.
Characteristics.
Yellow hypergiants occupy a region of the Hertzsprung–Russell diagram above the instability strip, a region where relatively few stars are found and where those stars are generally unstable. The spectral and temperature ranges are approximately A0-K2 and 4,000–8,000K respectively. The area is bounded on the high-temperature side by the "Yellow Evolutionary Void" where stars of this luminosity become extremely unstable and experience severe mass loss. The “Yellow Evolutionary Void” separates yellow hypergiants from luminous blue variables although yellow hypergiants at their hottest and luminous blue variables at their coolest can have approximately the same temperature near 8,000 K. At the lower temperature bound, yellow hypergiants and red supergiants are not clearly separated; RW Cephei (roughly 4,000 K, ) is an example of a star that shares characteristics of both yellow hypergiants and red supergiants.
Yellow hypergiants have a fairly narrow range of luminosities above (e.g. V382 Carinae at ) and below the Humphrey-Davidson limit at around . With their output peaking in the middle of the visual range, these are the most visually bright stars known with absolute magnitudes around −9 or −9.5 .
They are large and somewhat unstable, with very low surface gravities. Where yellow supergiants have surface gravities (log g) below about 2, the yellow hypergiants have log g around zero. In addition they pulsate irregularly, producing small variations in temperature and brightness. This produces very high mass loss rates, and nebulosity is common around the stars. Occasional larger outbursts can temporarily obscure the stars.
Yellow hypergiants form from massive stars after they have evolved away from the main sequence. Most observed yellow hypergiants have been through a red supergiant phase and are evolving back towards higher temperatures, but a few are seen in the brief first transition from main sequence to red supergiant. Supergiants with an initial mass less than will explode as a supernova while still red supergiants, while stars more massive than about will never cool beyond blue supergiant temperatures. The exact mass ranges depend on metallicity and rotation. Yellow supergiants cooling for the first time may be massive stars of up to or more, but post-red supergiant stars will have lost around half their initial mass.
Chemically, most yellow hypergiants show strong surface enhancement of nitrogen and also of sodium and some other heavy elements. Carbon and oxygen are depleted, while helium is enhanced, as expected for a post-main-sequence star.
Evolution.
Yellow hypergiants have clearly evolved off the main sequence and so have depleted the hydrogen in their cores. The majority of yellow hypergiants are postulated to be post-red supergiants evolving blueward, while more stable and less luminous yellow supergiants are likely to be evolving to red supergiants for the first time. There is strong chemical and surface gravity evidence that the brightest of the yellow supergiants, HD 33579, is currently expanding from a blue supergiant to a red supergiant.
These stars are doubly rare because they are very massive, initially hot class O-type main-sequence stars more than 15 times as massive as the Sun, but also because they spend only a few thousand years in the unstable yellow void phase of their lives. In fact, it is difficult to explain even the small number of observed yellow hypergiants, relative to red supergiants of comparable luminosity, from simple models of stellar evolution. The most luminous red supergiants may execute multiple "blue loops", shedding much of their atmosphere, but without actually ever reaching the blue supergiant stage, each one taking only a few decades at most. Conversely, some apparent yellow hypergiants may be hotter stars, such as the "missing" LBVs, masked within a cool pseudo-photosphere.
Recent discoveries of blue supergiant supernova progenitors have also raised the question of whether stars could explode directly from the yellow hypergiant stage. A handful of possible yellow supergiant supernova progenitors have been discovered, but they all appear to be of relatively low mass and luminosity, not hypergiants. SN 2013cu is a type IIb supernova whose progenitor has been directly and clearly observed. It was an evolved star around 8,000K showing extreme mass loss of helium and nitrogen enriched material. Although the luminosity is not known, only a yellow hypergiant or luminous blue variable in outburst would have these properties.
Modern models suggest that stars with a certain range of masses and rotation rates may explode as supernovae without ever becoming blue supergiants again, but many will eventually pass right through the yellow void and become low-mass low-luminosity luminous blue variables and possibly Wolf–Rayet stars after that. Specifically, more massive stars and those with higher mass loss rates due to rotation or high metallicity will evolve beyond the yellow hypergiant stage to hotter temperatures before reaching core collapse.
Structure.
According to the current physical models of stars, a yellow hypergiant should possess a convective core surrounded by a radiative zone, as opposed to a sun-sized star, which consists of a radiative core surrounded by a convective zone. Because of their extreme luminosity and internal structure, yellow hypergiants suffer high rates of mass loss and are generally surrounded by envelopes of expelled material. An example of the nebulae that can result is IRAS 17163-3907, known as the Fried Egg, which has expelled several solar masses of material in just a few hundred years.
The yellow hypergiant is an expected phase of evolution as the most luminous red supergiants evolve bluewards, but they may also represent a different sort of star. LBVs during eruption have such dense winds that they form a pseudo-photosphere which appears as a larger cooler star despite the underlying blue supergiant being largely unchanged. These are observed to have a very narrow range of temperatures around 8,000K. At the bistability jump which occurs around 21,000K blue supergiant winds become several times denser and could be result in an even cooler pseudo-photosphere. No LBVs are observed just below the luminosity where the bistability jump crosses the S Doradus instability strip (not to be confused with the Cepheid instability strip), but it is theorised that they do exist and appear as yellow hypergiants because of their pseudo-photospheres.
Known yellow hypergiants.
In Westerlund 1:
In other galaxies:


Virgilio Trettenero

Virgilio Trettenero (4 February 1822 – 23 May 1863) was an Italian mathematician and astronomer born in Recoaro Terme, Province of Vicenza, Italy. Active between 1848–1863, his name is linked to the creation of the stellar catalogs, a work initiated by Giovanni Padovani in 1838 using the meridian circle, which he purchased. The asteroid 16715 Trettenero, discovered on 20 October 1995 at the San Vittore Observatory, in Bologna, was named so in his honour.
Life.
Son of Domenico, owner of a hotel, and Domenica Maltauro, he studied at the University of Padua. In 1848 he appeared in the journal "Astronomische Nachrichten" connected to an article about the observations of the planet Neptune. The presence of the planet was postulated on the basis of the perturbation of the orbit of Uranus by Le Verrier and was observed for the first time only two years earlier.
In 1850-1851 he was nominated assistant in the department of physics and geodesy in Padua, and assistant astronomer at the Royal Observatory, under supervision of Professor Giovanni Santini in 1853. From 1859 to 1863 he was professor of physics at the faculty of mathematics and director of the physics department. In the same period he was appointed professor of astronomy in the faculty od philosophy. He died in the city of Padua, in the Veneto, northern Italy, and was succeeded by Michez Jacopo (1839-1873). His work summarizes 61 articles written in 14 years of study focused on the observation of asteroids, comets, eclipses, the calculation of planetary orbits with respect to the action of the disturbing planets of the solar system and ephemerides.


William Richardson (astronomer)

William Richardson (2 February 1796 – 23 March 1872) was a notable British astronomer at Greenwich Observatory who was later accused of murder.
Richardson was an amateur scientist who had an interest in the field of astronomy and was appointed in 1822 to work as an assistant at the observatory. In 1830 he was awarded the prestigious Gold Medal of the Royal Astronomical Society for outstanding researches which contributed to astronomy and geophysics, especially the pioneering work he did on the Constant of aberration.
Background.
William Richardson was born at Pocklington, Yorkshire. He was married to Anne Rogerson in the year 1821, a lady who was about two years younger than him. He already had six children by the time George Biddell Airy joined the Observatory. By the time he left the observatory he had nine surviving children in all.
During the census of 1841, he was staying in Greenwich with his two daughters Amelia and Ann Maria. During this period, he was staying separately from his wife who was staying at Chapmangate in Pocklington with the other children: Louisa, Lavinia, Lucy, and Julia. She was listed there as the head of this household, which meant that the two of them were separated at the time. In the following census of 1851, he was staying in Pocklington with three children of his, namely Lucy, William, and Julia with no mention of his wife's whereabouts.
Richardson became involved in a scandal which led to his arrest in January 1846 in Pocklington. He was then charged the following month, February, for colluding with his daughter in the murder of Theodore Horatio Richardson who was their incest son. On 11 May 1846, the two were put to trial at the Old Bailey court. He was then relieved of his job at the Observatory even though incest was not considered a crime in those days in Britain. The matter might have been dismissed had he not made the mistake of burying his son secretly in their garden, where a labourer digging a cesspool for Richardson discovered the child's coffin on 22 January 1846. In addition, neither the birth nor the death of the child had been recorded with the authorities. This then became the basis of the murder charge against him. This incident drew the attention from local to national audiences, with the proceedings of the court receiving considerable coverage by the major newspapers. The charges against the two were later dropped leading to their acquittal by the court. After this incident, Richardson moved back to live in Pocklington, where he lived until his death at the age of 75.
Career.
William Richardson was a blacksmith in his home village of Pocklington and was recommended to the Astronomer Royal by Troughton, a maker of instruments. This recommendation saw him given the position of assistant at the Royal Observatory at an annual salary of £100 plus £10 additional payment on consecutive three years in the service plus other allowances. His housing was also paid for by the Admiralty in order to provide suitable accommodation for him on his arrival at the Observatory. In the year 1830, he moved to a cottage on by road at Gang Lane now referred to as the Circus Street.
Richardson was acting as an advisor to Astronomer Royal John Pond when the latter decided in 1825 to increase the staffing at the Observatory by adding two new members. It was Richardson's recommendation to Pond that saw the recruitment of Yorkshiremen William Rogerson and Thomas Eli, which meant that half of the assistants at the observatory were from Yorkshire. Richardson was offered the position to become the director at the Madras Observatory in East India Company, but declined the offer due to alleged health concerns he had. This could have been a topflight position in his career had he not forgone it at this moment when he was full of ego.
In 1835, when Pond was preparing for his departure from the Observatory, he gave judgment on his six assistants saying that Richardson was the person he most regarded in the position, relating that he had been recommended for the position of an assistant by the late Mr. Troughton due to his knowledge in Elementary Mathematics. He was also considered as a "first-rate observer with the Circle" because of his immense mastery of the Circle computations and had also tasked with computing for other peoples catalogs especially the ones for Sir Thomas Brisbane, which had led to an increment in the salary he was being paid. The responsibilities highlighted for Richardson by the observatory before the reign of George Biddell Airy included doing the computations regarding the Troughton Circle and Jones Circle, although the payable amounts he was given for these external jobs was not clearly stated.
In 1835, when Pond was replaced by Airy, the standards at the observatory were falling. Airy came with the ambition to give the Observatory a new thrust and wanted to lay off the first assistants, one of whom was Richardson, even though the latter had received the Royal Astronomical Society's gold medal. This later helped him survive when the Observatory supported Airy's request which saw the laying off of his colleague Tailor. The coming of Airy to the Observatory marked the beginning of frustrating times to Richardson at Greenwich. When Airy was given the permission to amend the allowances in the year 1836, he ripped most off their allowances after which Richardson only received about £60 for rent and other domestic expenses e.g. coal fuel. Airy also managed to further the financial frustration of Richardson by blocking the traditional triennial pay rise, although this was overturned back to normal in 1843. The roles Richardson undertook in the reign of Airy were also changed, which saw him being limited to just making the observations with regard to the Equatorials, the Mural circle and the Zenith sector followed by diminishing them as requested.
Richardson's career at the Observatory in Greenwich ended in 1845 when he was released from his position by Airy due to his personal lifestyle issues. Though the incest wasn't much of a crime back then, he was still surrounded by several scandals and unsolved conspiracies about the death of his baby son. He was also charged for concealing the child from the registrar and ultimately for murder, which sealed his fate at the Observatory.
William Richardson was able to amass some considerable wealth in terms of several properties that he had acquired during his lifetime from 1792 to 1872 when he eventually died. These were in both Greenwich and Pocklington. The property holdings he had in Greenwich were: two neighbouring houses in Royal Hill and another one to the south of the junction of Peyton's area. He had further had acquired two more properties just adjacent to the first properties that he had. Among them was a big cottage in Peyton's place which was facing to the front of the glebe-house. This was the house that Richardson had stayed in in the year 1845. The fourth property that William Richardson owned was at the Royal Hill corner and Peyton's area. It was attached to a workshop. He then decided to sell all his properties and move to Pocklington.
Richardson was also able to acquire several other properties in Pocklington including The Star, an ancient building with a thatched roof, which was later damaged in a fire that had spread from the adjourning brewhouse on the 4th of March 1845. These buildings were later re-built and still exist as a result of the then modern London architecture that was used to design them. He had also had eight other properties in and around the market place. These included the Brewhouse and the residential area that he stayed in at the Parramatta Villa. His house was built in the 1861 to 1871 period. After his death, the building was sold and later its name changed from Parramatta Villa to Sherbutt House. This building was later modified to be used as an educational establishment by Charles Nichols.
Achievements.
During his period at the Royal Observatory, Richardson was credited with the data calculations which enabled the making of ""A catalog of 7385 stars: chiefly in the southern hemisphere, prepared from observations made ... at the observatory at Parramatta, New South Wales  ...”". In a piece published later in the year 1835 by the Admiralty. Richardson was also credited with an investigation into the subject of the Constant of aberration which won him the gold medal of the Royal Astronomical Society for his work. This work also inspired him to write about this topic in his book on Constant of Aberration a masterpiece of that time which was held highly by the astronomers in that period.
Richardson had vast knowledge in the field of Elementary Mathematics, a strength of his mental capabilities. He was thus able to keep the Circle computations in an organised way and was "a first-rate observer with the Circle" as described by Mr. Troughton. This trait really made him a real asset to the Royal Observatory. He was even able to make calculations for others which even involved cataloging for Sir Thomas Brisbane and the astronomical society.
Publications and works.
Richardson wrote a book on the investigation into the Constant of Aberration which was highly valued by the Royal Astronomical Society and the astronomers of his days. Later, he worked on “"A catalog of 7385 stars: chiefly in the southern hemisphere, prepared from observations made ...”" at the Parramatta observatory in New South Wales. The Admiralty then published it in the year 1835. He later wrote an article on the ""Greenwich assistants during 250 years" "which was published several years later in 1925 by Henry Hollis.


Maclaurin spheroid

A Maclaurin spheroid is an oblate spheroid which arises when a self-gravitating fluid body of uniform density rotates with a constant angular velocity. This spheroid is named after the Scottish mathematician Colin Maclaurin, who formulated it for the shape of Earth in 1742. In fact the figure of the Earth is far less oblate than Maclaurin's formula suggests, since the Earth is not homogeneous, but has a dense iron core. The Maclaurin spheroid is considered to be the simplest model of rotating ellipsoidal figures in hydrostatic equilibrium since it assumes uniform density.
Maclaurin formula.
For a spheroid with equatorial semi-major axis formula_1 and polar semi-minor axis formula_2, the angular velocity formula_3 about formula_2 is given by Maclaurin's formula
where formula_6 is the eccentricity of meridional cross-sections of the spheroid, formula_7 is the density and formula_8 is the gravitational constant. The formula predicts two possible equilibrium figures when formula_9, one is a sphere (formula_10) and the other is a very flattened spheroid (formula_11). The maximum angular velocity occurs at eccentricity formula_12 and its value is formula_13, so that above this speed, no equilibrium figures exist. The angular momentum formula_14 is
where formula_16 is the mass of the spheroid and formula_17 is the "mean radius", the radius of a sphere of the same volume as the spheroid.
Stability.
For a Maclaurin spheroid of eccentricity greater than 0.812670, a Jacobi ellipsoid of the same angular momentum has lower total energy. If such a spheroid is composed of a viscous fluid, and if it suffers a perturbation which breaks its rotational symmetry, then it will gradually elongate into the Jacobi ellipsoidal form, while dissipating its excess energy as heat. This is termed "secular instability". However, for a similar spheroid composed of an inviscid fluid, the perturbation will merely result in an undamped oscillation. This is described as "dynamic" (or "ordinary") "stability".
A Maclaurin spheroid of eccentricity greater than 0.952887 is dynamically unstable. Even if it is composed of an inviscid fluid and has no means of losing energy, a suitable perturbation will grow (at least initially) exponentially. Dynamic instability implies secular instability (and secular stability implies dynamic stability).


Heinrich Eduard von Lade

Heinrich Eduard von Lade (24 February 1817 – 7 August 1904) was a German banker and amateur astronomer.
He was born in Geisenheim, located along the banks of the Rhine river, the son of a wine merchant. He worked as a banker and exporter in Hamburg and Paris, and by the age of 44 he had earned enough to retire.
In 1861 he built a private estate Monrepos in Geisenheim. There he dedicated himself to culturing fruit and wine, and established a school at the site to teach the art. He also built an observatory on the estate to pursue his interest in selenography, or mapping the Moon.
He commissioned the construction of a lunar globe with one side in physical relief and the other with hashed relief and the crater names. This globe is now a very rare collector's item.
In 1901 he was elevated to nobility and became a baron. He died in Geisenheim, which is still famous for its wine and the Geisenheim Grape Breeding Institute.
Honors.
The crater Lade on the Moon is named after him, as is the asteroid 340 Eduarda.


Faith (meteorite)

Faith is a chondrite meteorite that was found in 1952 in Perkins County, South Dakota, United States. It has a mass of .


Margaret Turnbull

Margaret Carol "Maggie" Turnbull (born 1975) is an American astronomer and astrobiologist. She received her PhD in Astronomy from the University of Arizona in 2004. Turnbull is an authority on star systems which may have habitable planets, solar twins and planetary habitability. She is also an expert on the use of the coronagraph in the direct detection of exoplanets.
In 2002, Turnbull developed the HabCat along with Jill Tarter, a catalog of potentially habitable stellar systems. The following year Turnbull went on to further identify 30 particularly suitable stars from the 5,000 in the HabCat list that are within 100 light years of Earth.
In 2006, Turnbull drew up two shortlists of just five stars each. The first formed the basis of SETI radio searches with the Allen Telescope Array (Beta Canum Venaticorum, HD 10307, HD 211415, 18 Scorpii, and 51 Pegasi). The second are her top candidates for the Terrestrial Planet Finder (Epsilon Indi, Epsilon Eridani, 40 Eridani, Alpha Centauri B, and Tau Ceti).
Turnbull's work has continued to be an integral component in the search for life in the universe and she regularly contributes to the discussion on how life is defined and strategies for its detection. Her previous work on target selection with the HabCat list and expertise with coronagraphs have made her an important advocate for direct exoplanet imaging missions, and she served as Science Team Leader for the New Worlds Mission. In 2016, Turnbull became a leader of a Science Investigation Team for the Wide Field Infrared Survey Telescope (WFIRST), which is simulating mission data and selecting targets for the direct imaging exoplanet searches. In 2017, Turnbull worked with Stephen Kane to place constraints on the mass of Proxima Centauri b, the nearest exoplanet to our solar system.
Asteroid 7863 Turnbull, discovered by Brian A. Skiff at Anderson Mesa Station in 1981, was named in her honor. The official was published by the Minor Planet Center on September 28, 1999 ().
Politics.
In 2018, Turnbull ran for the office of Governor of Wisconsin as an independent, along with running mate Wil Losch. Turnbull received 18,779 votes (0.7%), finishing in fourth place, close behind the Libertarian candidate.


Battle of Suoi Bong Trang

The Battle of Suoi Bong Trang (23–24 February 1966) was an engagement fought between US, Australian and New Zealand forces, and the Viet Cong and North Vietnamese Army during the Vietnam War. The battle occurred during Operation Rolling Stone, an American security operation to protect engineers building a tactically important road in the vicinity of Tan Binh, in central Binh Duong Province, north-west of Bien Hoa airbase. During the fighting, soldiers from the US 1st Brigade, 1st Infantry Division and the 1st Battalion, Royal Australian Regiment (1 RAR), which had been attached for the operation, fought off a regimental-sized Viet Cong night assault. Repulsed by massed firepower from artillery and tanks, the Viet Cong suffered heavy casualties and were forced to withdraw by morning. After the attack, the Americans and Australians made no attempt to pursue the Viet Cong, focusing on securing the battlefield and evacuating their own casualties. The Viet Cong continued to harass the American sappers with occasional sniper and mortar fire, but these tactics proved ineffective, and the road was completed by 2 March.
Background.
Military situation.
During February 1966, as part of an American road-building program designed to challenge the Viet Cong's ability to manoeuvre in the areas around Saigon, the US 1st Engineer Battalion—under the command of Lieutenant Colonel Howard Sargent—had been engaged in constructing an all-weather road between Route 13 and Route 15 in central Binh Duong Province, west of Ben Cat, on the northern apex of the Viet Cong base area known as the Iron Triangle. This road was planned to cut the communist supply routes between War Zone C, the Mekong Delta, the Iron Triangle and War Zone D, while it would also link the two forward brigades of the US 1st Infantry Division between Phuoc Vinh and Lai Khe and help to extend the authority of the South Vietnamese government.
In response to the American moves, Viet Cong Local Force elements began harassing the sappers, subjecting them daily to sniping, laying mines and carrying out sabotage in an effort to hamper construction. A large American security operation known as Operation Rolling Stone was subsequently launched by elements of US 1st Division on 11 February, in an area of operations approximately north-west of Bien Hoa airbase. The US 1st Brigade under the command of Colonel Edgar N. Glotzbach was allocated the task, and he assigned one of his three battalions to guard the engineers on a rotating basis, while the other two would probe the Viet Cong positions nearby in order to keep them off balance.
Meanwhile, following a request from the American divisional commander, 1 RAR—under the command of Lieutenant Colonel Alex Preece—was detached from the US 173rd Airborne Brigade and placed under the operational command of the US 1st Division until 5 March. Major General William E. DePuy had selected the Australians specifically because of their reputation for dispersed, aggressive patrolling. Attached to support the infantry from 1 RAR were Australian M113s from 1 APC Troop, engineers from 3 Field Troop, Bell Sioux light observation helicopters and Cessna 180 fixed-wing aircraft from 161st Independent Reconnaissance Flight, and L5 Pack Howizters from 161st Battery, Royal New Zealand Artillery.
Prelude.
Opposing forces.
Headquarters US 1st Brigade was located about east of the engineer base camp in the vicinity of the hamlet of Tan Binh, just north of the new roadway and less than west of Route 16. The brigade's constituent battalions were widely dispersed carrying out search and destroy operations, and the area of operations was only lightly defended. Nevertheless, except for the harassment faced by the engineers, contact between the Americans and the Viet Cong had been infrequent during the first weeks of the operation. While US and Australian forces possessed only limited details regarding the location of Viet Cong Main Force regiments, Australian intelligence assessed that a minimum of two Local Force platoons, and possibly a Local Force company, were operating in the area but cautioned commanders that the Viet Cong probably had the ability to concentrate a Main Force battalion in the area with little warning. The concept of operations required the Australians to protect the engineer base, the laterite pit and road work parties over a distance of , as well as protecting engineer reconnaissance parties when they moved forward to plan new sections of the road.
On 19 February, 1 RAR was inserted by helicopter, taking over from 2nd Battalion, US 38th Infantry Regiment. Preece immediately instituted a program of twenty-four-hour dispersed patrolling, and within two days this had succeeded in reducing the level of Viet Cong activity against the road construction. Two platoons of American M48 Patton tanks were also moved into the area, patrolling by day with the Australian armoured personnel carriers, while securing the laterite pit at night. Several contacts took place and by 22 February the Australians began to suspect that a major attack on them was being planned, noting that they were now facing Main Force elements. In the early morning of 23 February three Viet Cong soldiers were killed in an Australian ambush, while several others were wounded but escaped. The dead soldiers were well equipped with new AK-47 assault rifles and webbing, and they were identified as being from 761st Main Force Regiment. Also captured was a large quantity of ammunition, rations and medical supplies. Later that night a North Vietnamese engineer officer was also killed in a separate ambush, adding further weight to the Australian suspicions. As dawn broke the next day, two half-platoon ambushes from B Company, 1 RAR—under the command of Major Ian McFarlane—engaged two squads of Viet Cong Main Force. Preece immediately warned Glotzbach of an imminent attack, and then informed Sargent that the Australians were moving to set up a defensive position, recommending that the engineers relocate in order to join them.
Meanwhile, to the west three battalions of Viet Cong 9th Division were massing for a decisive blow, preparing a regimental attack on the American and Australian positions. Units included J10 Battalion of the 761st Regiment, 707 Battalion of the 763rd Regiment and D800 Independent Battalion; in total around 2,000 men. By 20:00 they had completed a approach march and were in assembly areas near the village of Ap Bo, using local women and youths as porters to carry ammunition, equipment and supplies. Small reconnaissance parties moved forward as pathfinders, easily locating the American headquarters due to the large amount of noise and light it gave off. The Viet Cong regimental commander determined to attack on three separate axes from the east, and to then send a force around behind the Brigade Headquarters and assault from the west, thereby surrounding the defenders and preventing them from concentrating their forces in defence. Fire support was provided from two separate locations: with mortars deployed to the west, in between the Australians and the US 1st Brigade's headquarters, while mortars would fire from a position in Ap Bo to the south-east.
Battle.
Night assault, 23/24 February 1966.
By late afternoon on 23 February 1 RAR had adopted a position in all-round defence in the vicinity of the Suoi Bong Trang, a major creek to the west of the US 1st Brigade's headquarters, while the US engineers had moved into a new defensive position inside the Australian perimeter. Meanwhile, alerted by the Australians, a platoon of M48 Patton tanks from Troop B, 1st Squadron, US 4th Cavalry Regiment and a second howitzer field battery from 1st Battalion, US 5th Artillery Regiment had been moved in to defend the Brigade Headquarters. 1st Battalion, US 26th Infantry Regiment—under the command of Lieutenant Colonel Y.Y. Phillips—returned from the field and also deployed in defence by last light, augmenting Company B, 1st Battalion, US 28th Infantry Regiment. Additional ammunition was also brought forward, in anticipation of a likely Viet Cong attack.
At 22:00, soldiers from B Company, 1 RAR, occupying the western sector of the Australian perimeter noticed lights to their front. McFarlane subsequently requested artillery and mortar fire to target the location, but the request was declined by Preece. Meanwhile, a small Australian standing patrol that had deployed forward of the company main defensive position under the command of Private Walter Brunalli, observed the lights moving closer, east of the US 1st Brigade's headquarters. Two tanks had been positioned forward of the American positions, with a squad of infantry on the eastern approaches, and by midnight they had also reported sounds of movement and intermittent flashes of light through the trees. In the early morning of 24 February, just after midnight, sporadic firing was heard throughout the area. The forward American listening posts had detected small groups of Viet Cong moving outside the perimeter, killing two and forcing the remainder to withdraw into the darkness after one of the sentries opened fire. Glotzbach waited for the Viet Cong main effort, however, and withheld the bulk of the firepower at his disposal.
With their defences alerted, the Americans and Australians "stood to" for the next 45 minutes. The battle began at 01:45 with a heavy barrage of Viet Cong mortar and small arms fire. The Americans responded with small arms, machine-guns, tank fire, mortars and artillery and over the next hour the firing grew in intensity until, at 03:00, the Viet Cong switched their fires to the north-west side of the American perimeter, augmenting their barrage with recoilless rifles. Glotzbach expected a full-scale ground assault, but the Viet Cong had been held back by the weight of American firepower, with heavy artillery including and howitzers firing in support from Phuoc Vinh, in addition to the defenders' own artillery, which was now firing over open sights after lowering their tubes to fire directly at the Viet Cong positions. In total eight field batteries were available. Elsewhere, the Australian standing patrol had remained in position despite the proximity of the Viet Cong, and with the Americans pouring massive fire into the area they were soon caught in the crossfire. Brunalli was subsequently wounded in the arm.
Although the Australian position was not the focus of the attack, it too soon came under attack from mortars, killing an American sapper. With the base plate positioned between the Australians and the US 1st Brigade's headquarters there was initial confusion over the source of the rounds, and both Gloztbach and Preece accused the other of firing on their positions. However, after US aircraft arrived overhead to illuminate the battlefield the Australians were able to join the fighting, and they began firing at masses of Viet Cong who had become disorientated and were milling around on the battlefield. Earlier, a number of Australian ambushes had intercepted Viet Cong pathfinder groups and this had largely prevented the communists from conducting a final reconnaissance of their objectives. Unaware of the newly strengthened defences, they had assaulted into the combined firepower of two American field artillery batteries firing over open sights, as well as tanks supported by infantry. Using anti-personnel canister, flechette and splintex rounds, as well as prepositioned banks of Claymore mines, the Americans broke up several assaults with heavy casualties, while the Australians poured small arms fire into the flank of what was now turning into a costly and futile attack.
Viet Cong withdraw, 24 February 1966.
By 02:45 three Viet Cong soldiers had moved to within of Brunalli's standing patrol, taking up firing positions. The Australians killed one and wounded another who was dragged away by the third, before they withdrew to another location nearby. Meanwhile, the two American tanks forward of the US 1st Brigade's headquarters were overrun and their crews killed. Having suffered heavy losses, by 04:00 some of the Viet Cong began to retreat from the battlefield, and many were now filtering past 1 RAR. As groups of Viet Cong began to move past their position the standing patrol was now in an untenable position, clashing briefly with one group of 15 Viet Cong. McFarlane finally ordered the patrol to withdraw, so that he could engage with artillery and mortars. Moving to achieve a clean break, the patrol engaged another group of 10 Viet Cong with a volley of small arms fire, before withdrawing towards the company position in the darkness. Expecting to be followed up the Australians set up a snap ambush, killing another Viet Cong soldier before successfully completing the move back to their perimeter.
With the Viet Cong line of withdrawal carrying them past the Australian position, heavy fire was maintained on them as they attempted a partial retreat, resulting in further casualties. However, as daybreak neared the Viet Cong lingered, unwilling to commit to an all-out attack, but also unwilling to completely withdraw. Finally, the main Viet Cong attack began at 05:30. Earlier losses had been heavy, though, and they were unable to concentrate in sufficient numbers to mount a massed assault. Instead only a series of disjointed attacks followed, none more than 40 men strong. By 06:45 these attacks had been repelled by the Americans and the Viet Cong withdrew before dawn, avoiding the arrival of additional American air support.
Aftermath.
Casualties.
At first light the next morning Australian clearing patrols located 89 dead and 11 wounded Viet Cong in front of their positions. The bulk of the casualties had been inflicted by the Americans, but it was later determined that at least 17 Viet Cong had been killed by 1 RAR. Others had been disintegrated by artillery and tank fire and the battlefield was littered with shattered human remains, including severed limbs and chunks of flesh, while red pulp covered the rubber trees that were still standing. Later, 154 bodies were bulldozed into a B-52 bomb crater nearby, while it was estimated that a further 200 Viet Cong casualties had been removed from the battlefield. Fifteen Viet Cong had also been captured during the battle, as had a large quantity of equipment, including small arms and ammunition, crew-served weapons and grenades. The villagers of Ap Bo were again used by the Viet Cong to carry many of the dead and wounded from the battlefield with ox carts, and they also suffered a number of casualties from artillery and mortar fire landing in the area. In contrast, American casualties were limited, consisting of 11 killed and 72 wounded. Australian casualties were lighter still, with just two men wounded. One American tank had also been destroyed, while two tanks and four armoured personnel carriers were damaged. Overall, the commander of the combined US-Australian force believed that they had won an impressive victory, but his troops were exhausted and with ammunition running low, Glotzbach decided not to pursue the withdrawing force. Instead, the Americans and Australians focused on securing the battlefield and evacuating their own casualties.
Subsequent operations.
For the next two days, the Australians continued to provide protection to the US engineers before being replaced by an American infantry battalion. 1 RAR subsequently flew out on 26 February, returning to Bien Hoa airbase. Meanwhile, following the attack at Tan Binh the Viet Cong attempted to avoid further contact, choosing instead to harass the American work parties with occasional mortar and sniper fire. These tactics proved ineffective, and although the Americans lost a further three killed and 29 wounded, the road was completed by 2 March. The Americans then launched an extensive civic action program in an attempt to consolidate their gains, repairing damaged houses, distributing food and providing basic health care to the local population. Despite such efforts though, American commanders were pessimistic about the possibility of achieving any long term gains in Binh Duong Province unless the South Vietnamese Army was able to provide lasting protection for the local population. On 7 March, just five days after the completion of Operation Rolling Stone, the US 1st Brigade was redeployed with US 173rd Airborne Brigade and 1 RAR on Operation Silver City, sweeping the south-west sector of War Zone D.
At the strategic level the ARVN and the South Vietnamese government had both rallied after appearing on the verge of collapse and the threat against Saigon subsided. General William Westmoreland, commander of US forces in Vietnam, planned to adopt a more offensive strategy, and between January and December 1966 US troop levels rose from 210,000 to 327,000. The Australian government also increased its own commitment to the ground war in March 1966, announcing the deployment of a two battalion brigade—the 1st Australian Task Force (1 ATF)—with armour, aviation, engineer and artillery support; in total 4,500 men. Additional Royal Australian Air Force (RAAF) and the Royal Australian Navy (RAN) force elements would also be deployed and with all three services total Australian strength in Vietnam was planned to increase to 6,300 personnel. 1 RAR was subsequently replaced by 1 ATF which was allocated its own area of operations in Phuoc Tuy Province, thereby allowing the Australians to pursue operations more independently using their own counter-insurgency tactics and techniques. The task force arrived between April and June 1966, constructing a base at Nui Dat, while logistic arrangements were provided by the 1st Australian Logistic Support Group which was established at the port of Vung Tau.


9489 Tanemahuta


RX Andromedae

RX Andromedae is a variable star in the constellation of Andromeda. Although it is classified as a dwarf nova of the Z Camelopardalis (UGZ) type, it has shown low-luminosity periods typical of VY Sculptoris stars. However, for most of the time it varies from an apparent visual magnitude of 15.1 at minimum brightness to a magnitude of 10.2 at maximum brightness, with a period of approximately 13 days.
System.
RX Andromedae is a cataclysmic variable system, where a white dwarf with a mass of 0.8 and an M2 main sequence star are rotating around their center of mass. The main sequence star is overfilling its Roche lobe, so the white dwarf is stripping away matter from the companion star and accreting it through an accretion disk.
Variability.
Like the Z Camelopardalis variables, RX Andromedae shows some periods of roughly constant luminosity and others where its brightness oscillates between a magnitude of 10.2 at its maximum and one of 15.1 at its minimum. However, between 1996 and 1997 it was stuck at its minimum brightness like cataclysmic variables of VY Sculptoris type, before going back to the usual behaviour. This places RX Andromedae in a transitional state between those two kind of objects. The white dwarf and its accretion disk seems to be entirely responsible for this variability, and it's driven by changes in the accretion rate of the white dwarf.
Spectrum.
RX Andromedae has been extensively studied in optical and ultraviolet. It's also one of the few dwarf nova systems that have been detected at radio wavelengths.


Paleogeoscience

Paleogeosciences are those associated with the past states or processes associated with Earth science or geoscience. Earth science or geoscience is an all-embracing term referring to the fields of science dealing with planet Earth. These studies of earth's history encompass the Biosphere, Cryosphere, Hydrosphere, Atmosphere, and Lithosphere; the Geosphere. One of the most socially prominent facets of the paleogeosciences would be their applications to our changing climate system.
Etymology.
The term "Paleogeoscience" was coined by the "Collaboration and Cyberinfrastructure for Paleogeosciences" (C4P) research coordination network (RCN), a "National Science Foundation EarthCube" funded project intending to foster collaboration among paleogeoscientists, paleobiologists, bioinformaticists, stratigraphers, geochronologists, geographers, data scientists, and computer scientists with an aim to dramatically improve the application of modern data management approaches, data mining technologies, and computational methods to better analyze data within the paleogeosciences and other domains and disciplines.
Definition.
"Paleogeoscience" is the collective term for geologic studies that pertain to past geological processes. It combines paleoenvironmental and paleobiologial perspectives towards the goal of furthering our understanding of the interactions between life and the earth through time. It encompasses subjects such as "Paleobiology", "Paleoclimatology", "Geochemistry", "Geochronology", "Stratigraphy", "Paleobotany", "Paleogeography", and more.
Goals of paleogeosciences include understanding and recreating the Earth System over time for use in understanding the future of our Earth. It uses tangible data and proxy data.
See "Resources" section for links to catalogs of hundreds of resources for data, software, and sample collections pertaining to many realms of paleogeoscience.
Resources.
NSF EarthCube Paleogeoscience RCN Catalog of Software Resources
NSF EarthCube Paleogeoscience RCN Catalog of Physical Sample Repository Resources
NSF EarthCube Paleogeoscience RCN Catalog of Database Resources
OGC Catalog Service web service primer and instructions for accessing NSF EarthCube Paleogeoscience RCN Catalogs


Melton Memorial Observatory

Melton Memorial Observatory is an astronomical observatory owned and operated by University of South Carolina. It is named after Dr. William Davis Melton and built in 1928. It is located in Columbia, South Carolina (USA).


Nanoflares

A nanoflare is a very small episodic heating event which happens in the corona, the external atmosphere of the Sun.
The hypothesis of small impulsive heating events as a possible explanation of the coronal heating was first suggested by Thomas Gold
and then later developed and dubbed "nanoflares" by Eugene Parker.
According to Parker a nanoflare arises from an event of magnetic reconnection which converts the energy stored in the solar magnetic field into the motion of the plasma.
The plasma motion (thought as fluid motion) occurs at length-scales so small that it is soon damped by the turbulence and then by the viscosity. In such a way the energy is quickly converted into heat, and conducted by the free electrons along the magnetic field lines closer to the place where the nanoflare switches on. In order to heat a region of very high X-ray emission, over an area 1" x 1", a nanoflare of 1017 J should happen every 20 seconds, and 1000 nanoflares per second should occur in a large active region of
105 x 105 km2.
On the basis of this theory, the emission coming from a big flare could be caused by a series of nanoflares, not observable individually.
The nanoflare model has long suffered from a lack of observational evidence. Simulations predict that nanoflares produce a faint, hot (~10 MK) component of the emission measure. Unfortunately, current instruments, such as the Extreme-Ultraviolet Imaging Spectrometer on board Hinode, are not adequately sensitive to the range in which this faint emission occurs, making a confident detection impossible.
Recent evidence from the EUNIS sounding rocket has provided some spectral evidence for non-flaring plasma at temperatures near 9 MK in active region cores.
Nanoflares and coronal activity.
Telescopic observations suggest that the solar magnetic field, which theoretically is "frozen" into the gas of the plasma in the photosphere, expands into roughly semicircular structures in the corona. These coronal loops, which can be seen in the EUV and X-ray images (see the figure on the left), often confine very hot plasmas, with emissions characteristic of temperature of a one to a few million degrees.
Many flux tubes are relatively stable as seen in soft X-ray images, emitting at steady rate. However flickerings, brightenings, small explosions, bright points, flares and mass eruptions are observed very frequently, especially in active regions. These macroscopic signs of solar activity are considered by astrophysicists as the phenomenology related to events of relaxation of stressed magnetic fields, during which part of the energy they have stored is released ultimately into particle kinetic energy (heating); this could be via current dissipation, Joule effect, or any of several non-thermal plasma effects.
Theoretical work often appeals to the concept of magnetic reconnection to explain these outbursts.
Rather than a single large-scale episode of such a process, though, modern thinking suggests that a
multitude of small-scale versions reconnection, cascading together, might be a better description.
The theory of nanoflares then supposes that these events of magnetic reconnection, occurring at nearly the same time on small length-scales wherever in the corona, are very numerous, each providing an imperceptibly small fraction of the total energy required in a macroscopic event.
These nanoflares might themselves resemble very tiny flares, close one to each other, both in time and in space, effectively heating the corona and underlying many of the phenomena of solar magnetic activity.
Episodic heating often observed in active regions, including major events such as flares and coronal mass ejections could be provoked by cascade effects, similar to those described by the mathematical theories of catastrophes. In the hypothesis that the solar corona is in a state of self-organized criticality, the stressing of the magnetic field should be enhanced until a small perturbation switches on many small instabilities, happening together as it occurs in avalanches.
One of the experimental results often cited in supporting the nanoflare theory is the fact that the distribution of the number of flares observed in the hard X-rays is a function of their energy, following a power law with negative spectral index. A sufficiently large power-law index would allow the smallest events to dominate the total energy. In the energy range of normal flares, the index has a value of approximately -1.8
This falls short of the power-law index which would be required order to maintain the heating of the solar corona via the nanoflare hypothesis,
. A power-law index greater than -2 is required to maintain the temperature observed in the corona.
Nanoflares and coronal heating.
The problem of coronal heating is still unsolved, although research is ongoing and other evidence of nanoflares has been found in the solar corona.
The amount of energy stored in the solar magnetic field can account for the coronal heating necessary to maintain the plasma at this temperature and to balance coronal radiative losses
The radiation is not the only mechanism of energy loss in the corona: since the plasma is highly ionized and the magnetic field is well organized, the thermal conduction is a competitive process.
The energy losses due to the thermal conduction are of the same order of coronal radiative losses. The energy released in the corona which is not radiated externally is conducted back towards the chromosphere along the arcs.
In the transition region where the temperature is about 104 -105 K, radiative losses are too high to be balanced by any form of mechanical heating
The very high temperature gradient observed in this range of temperatures increases the conductive flux in order to supply for the irradiated power.
In other words, the transition region is so steep (the temperature increases from 10kK to 1MK in a distance of the order of 100 km) because the thermal conduction from the superior hotter atmosphere must balance the high radiative losses, as indicated to the numerous emission lines, which are formed from ionized atoms (oxygen, carbon, iron and so on).
The solar convection can supply the required heating, but in a way not yet known in detail. Actually, it is still unclear how this energy is transmitted from the chromosphere(where it could be absorbed or reflected), and then dissipated into the corona instead of dispersing into the solar wind.
Furthermore, where does it occur exactly ? : in the low corona or mainly in the higher corona, where the magnetic field lines open into the space heliosphere, driving the solar wind into the solar system.
The importance of the magnetic field is recognized by all the scientists:
there is a strict correspondence between the active regions, where the irradiated flux is higher (especially in the X-rays), and the regions of intense magnetic field.
The problem of coronal heating is complicated by the fact that different coronal features require very different amounts of energy.
It is difficult to believe that very dynamic and energetic phenomena such as flares and coronal mass ejections share the same source of energy with stable structures covering very large areas on the Sun: if nanoflares would have heated the whole corona, then they should be distributed so uniformly so as to look like a steady heating.
Flares themselves – and microflares, which when studied in detail seem to have the same physics – are highly intermittent in space and time, and would not therefore be relevant to any requirement for continuous heating.
On the other hand, in order to explain very rapid and energetic phenomena such as solar flares, the magnetic field should be structured on distances of the order of the metre.
The Alfvén waves generated by convective motions in the photosphere can go through the chromosphere and transition region, carrying an energy flux comparable to that required to sustain the corona.
Anyway, wavetrain periods observed in the high chromosphere and in the lower transition region are of the order of 3-5 min. These times are longer than the time taken by Alfvén waves to cross a typical coronal loop. This means that most of the dissipative mechanisms may provide enough energy only at distances further from the solar corona.
More probably, the Alfvén waves are responsible for the acceleration of the solar wind in coronal holes.
The theory initially developed by Parker of micro-nanoflares is one of those explaining the heating of the corona as the dissipation of electric currents generated by a spontaneous relaxation of the magnetic field towards a configuration of lower energy.
The magnetic energy is thus transformed into Joule heating.
The braiding of the field lines of the coronal magnetic flux tubes provokes events of magnetic reconnection with a consequent change of the magnetic field at small length-scales without a simultaneous alteration of the magnetic field lines at large length-scales.
In this way it can be explained why coronal loops are stable and so hot at the same time.
The Ohmic dissipation by currents could be a valid alternative to explain the coronal activity. For many years the magnetic reconnection has been invoked as the main power source of solar flares. However this heating mechanism is not very efficient in large current sheets, while more energy is released in turbulent regimes when nanoflares happen at much smaller scale-lengths, where non-linear effects are not negligible.


Symbiotic nova

Symbiotic novae are slow irregular eruptive variable stars with very slow nova-like outbursts with an amplitude of between 9 and 11 magnitudes. The symbiotic nova remains at maximum for one or a few decades, and then declines towards its original luminosity. Variables of this type are double star systems with one red giant, which probably is a Mira variable, and one white dwarf, with markedly contrasting spectra and whose proximity and mass characteristics indicate it as a symbiotic star. The red giant fills its Roche lobe so that matter is transferred to the white dwarf and accumulates until a nova-like outburst occurs, caused by ignition of thermonuclear fusion. The temperature at maximum is estimated to rise up to 200,000 K, similar to the energy source of novae, but dissimilar to the dwarf novae. The slow luminosity increase would then be simply due to time needed for growth of the ionization front in the outburst.
It is believed that the white dwarf component of a symbiotic nova remains below the Chandrasekhar limit, so that it remains a white dwarf after its outburst.
One example of a symbiotic nova is V1016 Cygni, whose outburst in 1971–2007 clearly indicated a thermonuclear explosion. Other examples are HM Sagittae and RR Telescopii.


Dark Ages (cosmology)


Edward Colborne Baber

Edward Colborne Baber (30 April 1843 – 16 June 1890) was an English orientalist and traveller.
Life.
Born at Dulwich, he studied at Rossall Junior School, Christ's Hospital and Magdalene College, Cambridge, where he graduated in 1867.
Having learned Chinese, he started working at the British embassy in Beijing the same year, where he quickly advanced through the ranks. During his tenure he made three journeys to the interior of China; one to the Burmese border in 1876, one to the Sichuan highlands the next year (where he visited the Leshan Giant Buddha, and the last, in 1878, northwards through the mountains from Chongqing. His travels and discoveries were described in books, and in 1883 he received the Royal Geographical Society's Patron's Medal.
From 1885 to 1886, Baber acted as consul-general in Korea.
Then he was appointed political resident at Bhamo on the upper Irrawaddy, where he died, unmarried, on 16 June 1890.


Stonehenge, Avebury and Associated Sites

Stonehenge, Avebury and Associated Sites is a UNESCO World Heritage site (WHS) located in Wiltshire, England. The WHS covers two large areas of land separated by about , rather than a specific monument or building. The sites were inscribed as co-listings in 1986. Some of the large and well known monuments within the WHS are listed below, but the area also has an exceptionally high density of small-scale archaeological sites, particularly from the prehistoric period. More than 700 individual archaeological features have been identified. There are 160 separate Scheduled Monuments, covering 415 items or features.
Stonehenge and Associated Monuments.
The Stonehenge area of the WHS is in south Wiltshire. It covers an area of 26 square km and is centred on the prehistoric monument of Stonehenge. Ownership is shared between English Heritage, the National Trust, the Ministry of Defence, the RSPB, Wiltshire Council, and private individuals and farmers.
Avebury and Associated Monuments.
The Avebury area of the WHS covers an area of 22.5 km² and is centred on the prehistoric Avebury Henge, about north of Stonehenge.
Museum and archive collections.
The main museums are the Alexander Keiler Museum at Avebury, Salisbury Museum, and Wiltshire Museum in Devizes.
Other museums with material from Stonehenge and Avebury include the British Museum, National Museum of Wales, Cambridge University Museum of Archaeology and Anthropology and the Ashmolean Museum. Other archives include the Historic England Archive in Swindon, the Wiltshire and Swindon History Centre in Chippenham, and the Bodleian Library at Oxford.