Apparent and Absolute Magnitude
Two specific types of magnitudes distinguished by astronomers are:
- Apparent magnitude, the apparent brightness of an object. For example, Alpha Centauri has higher apparent magnitude (i.e. lower value) than Betelgeuse, because it is much closer to the Earth.
- Absolute magnitude, which measures the luminosity of an object (or reflected light for non-luminous objects like asteroids); it is the object's apparent magnitude as seen from a certain distance. For stars it is 10 parsecs (32.6 light years). Betelgeuse has much higher absolute magnitude than Alpha Centauri, because it is much more luminous.
Usually only apparent magnitude is mentioned, because it can be measured directly; absolute magnitude can be calculated from apparent magnitude and distance using;
This is known as the distance modulus, where d is the distance to the star measured in parsecs.
Read more about this topic: Magnitude (astronomy)
Famous quotes containing the words apparent, absolute and/or magnitude:
“[Women’s] apparent endorsement of male supremacy is ... a pathetic striving for self- respect, self-justification, and self-pardon. After fifteen hundred years of subjection to men, Western woman finds it almost unbearable to face the fact that she has been hoodwinked and enslaved by her inferiors—that the master is lesser than the slave.”
—Elizabeth Gould Davis (b. 1910)
“... the absolute freedom of woman will be the dawn of the day of man’s regeneration. In raising her he will elevate himself.”
—Tennessee Claflin (1846–1923)
“He all their ammunition
And feats of war defeats
With plain heroic magnitude of mind
And celestial vigour armed;”
—John Milton (1608–1674)