Answer Happy

Why don't astronomers just measure the absolute magnitudes of every object in the sky instead of having to deal with the difference between apparent magnitude & absolute magnitude? Absolute magnitude measurements require images taken from a distance of 10 pc away from the object in question and we don't have the technology to do that right now. Trick question - apparent magnitude & absolute magnitude are the same thing, but you need to convert between the scales. Apparent magnitude was measured by Hipparchus, so we don't use it anymore. Absolute magnitude can only be determined when the distance to the object is known. (Since the apparent magnitude is easy to measure, it's just how the object looks in Earth's sky, the distance is the main problem). Actually, astronomers only use apparent magnitude because it puts everything from the perspective of Earth.