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Eratosthenes
(Encyclopedia)Eratosthenes ĕrətŏsˈthənēz [key], c.275–c.195 b.c., Greek scholar, b. Cyrene. A pupil of Callimachus in Athens, he became (c.240 b.c.) head of the library at Alexandria. Known for his versatil...perturbation
(Encyclopedia)perturbation pŭrˌtərbāˈshən [key], in astronomy and physics, small force or other influence that modifies the otherwise simple motion of some object. The term is also used for the effect produce...Adams, John Couch
(Encyclopedia)Adams, John Couch, 1819–92, English astronomer, grad. St. John's College, Cambridge, 1843. By mathematical calculation based on irregularities in the motion of Uranus, he predicted the position of t...Hertzsprung, Ejnar
(Encyclopedia)Hertzsprung, Ejnar īˈnär hĕrtsˈspro͞ong [key], 1873–1967, Danish astronomer. Although trained as a chemical engineer, Hertzsprung made his career in astronomy, specializing in exacting photogr...mass-luminosity relation
(Encyclopedia)mass-luminosity relation, in astronomy, law stating that the luminosity of a star is proportional to some power of the mass of the star. More massive stars are in general more luminous. For stars on t...Banneker, Benjamin
(Encyclopedia)Banneker, Benjamin, 1731–1806, African-American inventor, astronomer, and mathematician, b. Baltimore co., Md., at what is now Ellicott's Mills. A free black, Banneker was essentially self-taught. H...Poisson, Siméon Denis
(Encyclopedia)Poisson, Siméon Denis sēmāôNˈ dənēˈ pwäsôNˈ [key], 1781–1840, French mathematician and physicist. From 1802 he taught at the École polytechnique, Paris, and was also on the faculty of sc...Heliopolis, ancient city, Egypt
(Encyclopedia)Heliopolis hēlēŏpˈəlĭs [key] [Gr.,=city of the sun], ancient city, N Egypt, in the Nile delta, 6 mi (10 km) below modern Cairo. It was noted as the center of sun worship, and its god Ra or Re wa...blue shift
(Encyclopedia)blue shift or blueshift, in astronomy, the systematic displacement of individual lines in the spectrum of a celestial object toward the blue, or shorter wavelength, end of the visible spectrum. The am...Bode, Johann Elert
(Encyclopedia)Bode, Johann Elert yōˈhän āˈlĕrt bōˈdə [key], 1747–1826, German astronomer. From 1772 to 1825 he was astronomer of the Academy of Science, Berlin, and from 1786, director of the Berlin Obse...Browse by Subject
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