Astronomers have two ways of measuring the brightness of a star, apparent magnitude and absolute brightness. Which statement best explains the difference between apparent magnitude and absolute brightness?

Astronomers define star brightness in terms of apparent magnitude — how bright the star appears from Earth — and absolute magnitude — how bright the star appears at a standard distance of 32.6 light-years, or 10 parsecs. (A light-year is the distance light travels in one year — about 6 trillion miles, or 10 trillion kilometers.) Astronomers also measure luminosity — the amount of energy (light) that a star emits from its surface.

Explanation:

A glance at the night sky above Earth shows that some stars are much brighter than others. However, the brightness of a star depends on its composition and how far it is from the planet.

Astronomers define star brightness in terms of apparent magnitude — how bright the star appears from Earth — and absolute magnitude — how bright the star appears at a standard distance of 32.6 light-years, or 10 parsecs. (A light-year is the distance light travels in one year — about 6 trillion miles, or 10 trillion kilometres.) Astronomers also measure luminosity — the amount of energy (light) that a star emits from its surface.