The Magnitude of Stars


HOME	The largest stars are 1,000 times the size of Sun. The smallest are still very big. They are about the size of the largest planet, Jupiter (approximately 88,865 miles in diameter at its equator). It is possible to photograph over 10,000 stars. You can see about 6,000 stars without a telescope. Most of the stars that can be seen without a telescope are closer, bigger or hotter than the stars that cannot be seen without a telescope. The brightest star in the night sky is Sirius, in the constellation Canis Major (Big Dog). It has a magnitude of –1.5, which makes it brighter than most planets. Magnitude is the measurement of how bright stars are. There are two kinds of magnitude - apparent magnitude and absolute magnitude. Apparent magnitude is how bright a star appears to be. Absolute magnitude is how bright a star really is compared to other stars. The magnitude of a star depends on three things. They are: the distance they are from us (closer is brighter); how big it is (bigger is brighter); and how hot it is (hotter is brighter). A star’s brightness is measured in magnitude. The first astronomers studied the star’s brightness by the eye (how it looks). Photographs can also be used to study a star’s brightness. Today, we use visual magnitudes (by common sight), ultraviolet magnitudes (a special type of light), infrared magnitudes (a special type of heat light) and photographic (special types of photo) *magnitudes.