Columbia Encyclopedia

(Encyclopedia) Titan tīˈtən [key], in astronomy, the largest of the named moons, or natural satellites, of Saturn. Also known as Saturn VI (or S6), Titan is 3,200 mi (5,150 km) in diameter, orbits Saturn at a mea...

(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...

(Encyclopedia) Neptune, in astronomy, 8th planet from the sun at a mean distance of about 2.8 billion mi (4.5 billion km) with an orbit lying between those of Uranus and the dwarf planet Pluto; its period of revolut...

(Encyclopedia) ether or aether, in physics and astronomy, a hypothetical medium for transmitting light and heat (radiation), filling all unoccupied space; it is also called luminiferous ether. In Newtonian physics a...

(Encyclopedia) Mercury, in astronomy, nearest planet to the sun, at a mean distance of 36 million mi (58 million km); its period of revolution is 88 days. Mercury passes through phases similar to those of the moon a...

(Encyclopedia) Arecibo Observatory, radio-astronomy facility located near Arecibo, Puerto Rico, part of the National Astronomy and Ionosphere Center. Conceived by, designed by, and built under the supervision of Wil...

(Encyclopedia) Stratospheric Observatory for Infrared Astronomy: see infrared astronomy. ...

(Encyclopedia) Uranus yo͝orāˈnəs, yo͝orˈə– [key], in astronomy, 7th planet from the sun, at a mean distance of 1.78 billion mi (2.87 billion km), with an orbit lying between those of Saturn and Neptune; its...

(Encyclopedia) radio astronomy, study of celestial bodies by means of the electromagnetic radio frequency waves they emit and absorb naturally. Radio waves also come from outside the Milky Way. These extragalact...

(Encyclopedia) infrared astronomy, study of celestial objects by means of the infrared radiation they emit, in the wavelength range from about 1 micrometer to about 1 millimeter. All objects, from trees and building...