Question

Gloria is at the observatory and is examining a newly discovered star through a powerful telescope. She wants to find out how bright the star actually is. What information does she need to calculate the absolute magnitude of a star?

a) Color and temperature of the star
b) Color and composition of the star
c) Apparent magnitude and distance from Earth of the star
d) Color and distance from Earth of the star

Answer 1

To find the absolute magnitude of a star, Gloria needs to determine the star's apparent magnitude and its distance from Earth.

Step-by-step explanation:

To calculate the absolute magnitude of a star, like the newly discovered star Gloria is examining, one needs to know the star's apparent magnitude and the distance from Earth to the star. The apparent magnitude is a measure of the star's brightness as seen from Earth, which accounts for the star's luminosity and its distance from Earth. Since luminosity refers to the total amount of energy a star emits per second, the apparent magnitude by itself does not provide enough information to determine how bright the star truly is without also knowing the star's distance. Knowing both these pieces of information allows astronomers to compensate for the dimming effects of distance on light, enabling them to calculate the star's absolute magnitude, which is a measure of its intrinsic brightness independent of its distance to us.