Messier 7
ptolemy
['benjamin franklin', 'nauchnyj', 'karl reinmuth', 'george van biesbroeck', 'odin', 'ward cunningham', 'paolo maffei', 'pelageya shajn', 'marguerite laugier', 'sequoyah', 'urbain le verrier', 'marie curie', 'john grinder', 'isaac newton', 'urata', 'nikolai stepanovich chernykh', 'evangelista torricelli', 'moog', 'julian huxley', 'tycho', 'sergey belyavsky', 'charles darwin', 'grigory neujmin', 'humphry davy', 'james bradley', 'arnold schoenberg', 'harold urey', 'michael brown', 'microsoft', 'crimean astrophysical observatory', 'carl friedrich gauss', 'brouwer', 'harlow shapley', 'dmitri mendeleev', 'michael faraday', 'edwin hubble', 'otto hahn', 'lyudmila zhuravleva', 'conway', 'emmett chapman', 'henry bessemer', 'eleanor helin', 'james watt', 'fabian gottlieb von bellingshausen', 'hyperboloid', 'lyudmila chernykh', 'georg cantor', 'alonzo church', 'leibniz', 'loneos', 'james dunlop', 'heinrich ruhmkorff', 'egide walschaerts', 'pieter zeeman', 'gotthold ephraim lessing', 'henri lebesgue', 'bartolomeo cristofori', 'alessandro malaspina', 'max wolf', 'frederick scott archer', 'vapnik', 'lee de forest', 'hyperloop', 'august derleth', 'speke', 'sir winston churchill', 'indiana asteroid program', 'donald knuth', 'nicolas bourriaud', 'ingrid', 'oak ridge observatory', 'ernest rutherford', 'mikhail lazarev', 'harry edwin wood', 'purple mountain observatory', 'hendrik van gent', 'christopher cockerell', 'george westinghouse', 'gustav rose', 'joseph priestley', 'ernest hemingway', 'anselm', 'bickley', 'blackberry', 'silas weir mitchell', 'christopher alexander', 'werner heisenberg', 'chad trujillo', 'carl gustav mosander', 'cornelis johannes van houten', 'george berkeley', 'liisi oterma', 'carl auer von welsbach', 'lewis swift', 'cavendish', 'ole kirk christiansen', 'sir nigel gresley', 'lord rayleigh', 'franz kaiser']
Messier 7
Messier 7 or M7, also designated NGC 6475 and sometimes known as the Ptolemy Cluster, is an open cluster of stars in the constellation of Scorpius. The cluster is easily detectable with the naked eye, close to the "stinger" of Scorpius (also called Scorpio). With a declination of -34.8°, it is the southernmost Messier object. M7 has been known since antiquity; it was first recorded by the 1st-century Greek-Roman astronomer Ptolemy, who described it as a nebula in 130 AD. Italian astronomer Giovanni Batista Hodierna observed it before 1654 and counted 30 stars in it. In 1764, French astronomer Charles Messier catalogued the cluster as the seventh member in his list of comet-like objects. English astronomer John Herschel described it as "coarsely scattered clusters of stars". Telescopic observations of the cluster reveal about 80 stars within a field of view of 1.3° across. At the cluster's estimated distance of 980 light years this corresponds to an actual diameter of 25 light years. The tidal radius of the cluster is 40.1 ly (12.3 pc) and it has a combined mass of about 735 times the mass of the Sun. The age of the cluster is around 200 million years while the brightest member star is of magnitude 5.6. In terms of composition, the cluster contains a similar abundance of elements other than hydrogen and helium as the Sun.