In
astronomy, absolute magnitude is the
apparent magnitude, m, an object would have if it were at a standard
luminosity distance away from us, in the absence of
interstellar extinction. It allows the overall brightnesses of objects to be compared without regard to distance.The absolute magnitude uses the same convention as the visual magnitude, with a ~2.512 difference in
brightness between step rates (because 2.5125 ≈ 100). The
Milky Way, for example, has an absolute magnitude of about -20.5. So a
quasar at an absolute magnitude of -25.5 is 100 times brighter than our
galaxy. If this particular quasar and our galaxy could be seen side by side at the same distance, the quasar would be 5 magnitudes (or 100 times) brighter than our galaxy.
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