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magnitude
subject			fact

magnitude	has definition A logarithmic brightness scale for astronomical objects. See Appendix.
	has definition The measured brightness of a celestial body. dim objects have magnitudes of high numbers, bright objects have magnitudes of low or even negative numbers. Seen from earth, stars of (apparent) magnitude 6 or higher cannot be detected with the naked eye. The Full Moon has a magnitude of -11, and the Sun one of -26.8. in order to standardize measurements of the brightness of more distant objects, the system of absolute magnitude is used. A measure of the radiation at all wavelengths emitted by a star is known as the bolometric magnitude.
	has definition The measure of a star's brightness. apparent magnitude measures a star's apparent brightness - that is, how bright a star looks from Earth. absolute magnitude measures a star's intrinsic brightness - that is, how much light the star actually emits.
	has definition The brightness of a star or planet, expressed on a scale in which lower numbers mean greater brightness. Apparent magnitude indicates the brightness of objects as we see them from earth, regardless of their distance. Absolute magnitude is defined as the apparent magnitude a star would have if viewed from a distance of ten parsecs, or 32.6 light-years. each step in magnitude equals a difference of 2.5 times in brightness: the brightest stars in the sky are apparent magnitude 1; the dimmest, 6. The magnitudes of extremely bright objects are expressed in negative values - e.g., the apparent magnitude of the Sun is about -26.
	has definition An arbitrary number, measured on a logarithmic scale, used to indicate the brightness of an object. Two stars differing by 5 mag differ in luminosity by 100. 1 magnitude is the fifth root of 100, or about 2.512. The brighter the star, the lower the numerical value of the magnitude (see also Pogson's ratio).
	has definition A measure. on a logarithmic scale, used to indicate the brightness of a celestial object. A 1-magnitude difference in brightness between two stars corresponds to a difference in luminosity by 100.4 or 2.51; 5 magnitudes corresponds to factor of 100 in luminosity.
	is a kind of radiation measurement
radiation measurement	has unit radiation unit
number	has value

Kinds of magnitude :

• absolute magnitude (1 kind, 6 facts) - A measure of the intrinsic brightness of a star or galaxy. Absolute magnitude is defined as the apparent magnitude the star or galaxy would have if it were 32.6 light-years (10 parsecs) from Earth. The lower an object's absolute magnitude, the greater its intrinsic brightness. For example, the Sun has an absolute magnitude of +4.83, while Sirius, whose intrinsic brightness is greater, has an absolute magnitude of +1.43. A star that is one absolute magnitude brighter than another (e.g., +4 versus +5) is 2.5 times intrinsically brighter; a star that is 5 absolute magnitudes brighter is 100 times intrinsically brighter; and a star that is 10 absolute magnitudes brighter is 10000 times intrinsically brighter., The absolute magnitude (g) of a solar-system body such as an asteroid is defined as the brightness at zero phase angle when the object is 1 AU from the Sun and 1 AU from the observer.
• apparent magnitude (11 kinds, 34 facts) - 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., 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 m_v, of Sun, -26.5 mag. A sixth-magnitude star is just barely visible to the naked eye.