Astronomy Practice Exam

What does apparent magnitude measure regarding a star?

1. The temperature of the star

2. How bright a star appears to be

3. The distance of the star from Earth

4. The star's mass

The correct answer is: How bright a star appears to be

Apparent magnitude is a measure of how bright a star appears as seen from Earth. This measurement takes into account the star's intrinsic brightness (known as absolute magnitude), its distance from Earth, and any interstellar matter that may dim the light along the way. Apparent magnitude is a logarithmic scale, meaning that a difference of 5 magnitudes corresponds to a brightness difference of a factor of 100. A lower numerical value indicates a brighter star, while a higher value indicates a dimmer star. Temperature, distance, and mass of a star are related to its characteristics and evolution, but they are not what the apparent magnitude directly measures. Temperature can influence a star's intrinsic brightness but is not what is captured by the apparent magnitude. Distance affects apparent brightness, but the apparent magnitude itself does not indicate how far away a star is, and mass is a characteristic that pertains to the star's formation and lifecycle, not its brightness as observed from Earth.