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Hadar, in astronomy

(Encyclopedia)Hadar or Beta Centauri bāˈtə sĕntôrˈē [key], bright star in the constellation Centaurus; 1992 position R.A. 14h01.7m, dec. −60°13′. A bluish-white giant of spectral class B1 II, it has an ...

Castor, in astronomy

(Encyclopedia)Castor kăsˈtər [key], bright star in the constellation Gemini; Bayer designation α Geminorum; 1992 position R.A. 7h34.1m, Dec. +31°54′. Slightly dimmer than Pollux, with which it forms the Twin...

Despina

(Encyclopedia)Despina, in astronomy, one of the natural satellites, or moons, of Neptune. ...

corona, in astronomy

(Encyclopedia)corona, luminous envelope surrounding the sun, outside the chromosphere. Its density is less than one billionth that of the earth's atmosphere. The corona is visible only at the time of totality durin...

gamma-ray astronomy

(Encyclopedia)gamma-ray astronomy, study of astronomical objects by analysis of the most energetic electromagnetic radiation they emit. Gamma rays are shorter in wavelength and hence more energetic than X rays (see...

ultraviolet astronomy

(Encyclopedia)ultraviolet astronomy, study of celestial objects by means of the ultraviolet radiation they emit, in the wavelength range from about 90 to about 350 nanometers. Ultraviolet (UV) line spectrum measure...

Nereid

(Encyclopedia)Nereid nĭrˈēəd [key], in astronomy, one of the eight known moons, or natural satellites, of Neptune. ...

Thalassa

(Encyclopedia)Thalassa thəlăsˈə, thălˈəsə [key], in astronomy, one of the natural satellites, or moons, of Neptune. ...

neutrino astronomy

(Encyclopedia)neutrino astronomy, study of stars by means of their emission of neutrinos, fundamental particles that result from nuclear reactions and are emitted by stars along with light. Approximately 100 billio...

X-ray astronomy

(Encyclopedia)X-ray astronomy, study of celestial objects by means of the X rays they emit, in the wavelength range from 0.01 to 10 nanometers. X-ray astronomy dates to 1949 with the discovery that the sun emits X ...