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- Number of terms: 3726
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a group of bright stars which form a conspicuous pattern on the celestial sphere
Industry:Astronomy
Also called planetoids or minor planets, the asteroids are tiny planets most of which orbit the Sun between Mars and Jupiter. The largest - and the first discovered - is Ceres, with a diameter of 1,003 km. It is estimated that there may altogether be no fewer than 40000. A few have very elliptical orbits and cross the orbits of several other (major) planets. One or two even have their own satellites (moons.)
Industry:Astronomy
A region of space lying between Mars (1.5 AU) and Jupiter (5.2 AU), where the great majority of the asteroids are found. None of the belt asteroids have retrograde motion.
Industry:Astronomy
The branch of astronomy that deals with measuring the positions of celestial objects, especially stars. Astrometrists measure parallaxes and proper motions, which allow astronomers to determine the distances and velocities of the stars.
Industry:Astronomy
The time and azimuth at which a celestial body crosses the astronomical horizon of an oberver.
Industry:Astronomy
The change in direction of travel (bending) of a light ray as it passes obliquely through the atmosphere. As a result of refraction, the observed altitude of a celestial object is greater than its geometric altitude. The amount of refraction depends on the altitude of the object and on atmospheric conditions.
Industry:Astronomy
Globular cluster stars, which are found in that part of the HR diagram that connects the top pf the giant tip with the horizontal branch stars.
Industry:Astronomy
volatile element that tends to be found in the atmosphere of a planet or asteroid
Industry:Astronomy
An optical device usually comprising two thin prisms which can rotate to compensate for the elongation of a star image caused by the wavelength dependence of the refractive index of air.
Industry:Astronomy
One-twelfth the mean mass of an atom of carbon 12 (including the orbital electrons.)
Industry:Astronomy
