GO IN DEPTH

# Star Light

Photo Credit: Clipart.com

### Introduction

In the Motivation, you discussed relative brightness with your teacher. You will now expand on that concept by studying apparent magnitude using the resources on the Star Light student esheet.

Describe what is meant by the term apparent magnitude.

Describe the scale that is used for apparent magnitude. Do brighter stars have higher or lower magnitudes?

Describe the difference between luminosity and apparent magnitude.

Why does luminosity not depend on the distance of a star?

Why can a star that is very high in luminosity be of high apparent magnitude?

### The Relation Between Brightness and Luminosity

Describe the mathematical relationship among luminosity, distance, and brightness.

### How Far is a Light-Year?

How much distance in kilometers and miles does light travel in a single second?

In one year, approximately how many kilometers and miles does light travel?

An astronomical unit is the distance between what two objects in the galaxy?

An astronomical unit is how many kilometers and miles?

How long does it take light to travel one astronomical unit?

After the sun, what is the closest star to Earth and how many light-years away is it?

How many astronomical units are in one light-year?