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:
“The apparent rulers of the English nation are like the imposing personages of a splendid procession: it is by them the mob are influenced; it is they whom the spectators cheer. The real rulers are secreted in second-rate carriages; no one cares for them or asks after them, but they are obeyed implicitly and unconsciously by reason of the splendour of those who eclipsed and preceded them.”
—Walter Bagehot (18261877)
“We have imagined ourselves a special creation, set apart from other humans. In the last twentieth century, we see that our poverty is as absolute as that of the poorest nations. We have attempted to deny the human condition in our quest for power after power. It would be well for us to rejoin the human race, to accept our essential poverty as a gift, and to share our material wealth with those in need.”
—Robert Neelly Bellah (20th century)
“Sometimes youre overwhelmed when a thing comes, and you do not realize the magnitude of the affair at that moment. When you get away from it, you wonder, did it really happen to you.”
—Marian Anderson (19021993)