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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
Rotation of the line of apsides in the plane of the orbit; (in a binary) precession of the line of apsides due to mutual tidal distortion.
Industry:Astronomy
colourless, odourless gas comprising 1% of the atmosphere
Industry:Astronomy
Angular distance (measured in the plane of the object's orbit and in the direction of its motion) from the ascending node to the perihelion point.
Industry:Astronomy
a telescope composed of an array of separete individual elements acting in concert
Industry:Astronomy
a metalloid element with two main forms, grey α arsenic and β arsenic
Industry:Astronomy