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A system of three lenses which, taken together, correct for spherical aberration, chromatic aberration, and coma.
Industry:Astronomy
The point in the orbit of one component of a binary system which is farthest from the center of mass of the system.
Industry:Astronomy
The point in a star's orbit farthest from the Galactic center.
Industry:Astronomy
The point at which a body in orbit around the Earth reaches its farthest distance from the Earth.
Industry:Astronomy
1) A measure of how bright a star looks in the sky. The brighter the star, the smaller the apparent magnitude. A star that is one magnitude brighter than another (e.g., +1 versus +2) looks 2.5 times brighter. The brightest star of all, of course, is the Sun, whose apparent magnitude is -26.74, followed by Sirius, whose apparent magnitude is -1.46, Canopus (-0.72), Alpha Centauri (-0.27), Arcturus (-0.04), and Vega (+0.03). Stars of the Big Dipper are fainter, most of them around magnitude +2. On a clear, dark night, the unaided eye can see stars as faint as apparent magnitude +6, and the largest telescopes penetrate to apparent magnitude +30.
2) Measure of the observed brightness of a celestial object as seen from the Earth. It is a function of the star's intrinsic brightness, its distance from the observer, and the amount of absorption by interstellar matter between the star and the observer. The mv, of Sun, -26.5 mag. A sixth-magnitude star is just barely visible to the naked eye.
Industry:Astronomy
1) A period of time based on the revolution of the Earth around the Sun, where a year is defined as the mean interval between successive passages of the Earth through perihelion.
2) The interval between two successive perihelion passages of Earth.
Industry:Astronomy
The direction in the sky away from which the Sun seems to be moving (at a speed of 19.4 km s-1) relative to general field stars in the Galaxy.
Industry:Astronomy
The weak form of the anthropic principle states that life can exist only during a brief period of the history of our universe. The strong form of the principle states that out of all possible values for the fundamental constants of nature and the initial conditions of the universe, only a small fraction could allow life to form at all, at anytime. (See boundary conditions; fundamental constants of nature..)
Industry:Astronomy
The belief that humans are central to the universe.
Industry:Astronomy
The projection of human attributes onto nonhuman entities such as animals, the planets, or the universe as a whole.
Industry:Astronomy
