Star Light


The sky is full of bright objects, such as stars, planets, and galaxies. In this lesson, you'll explore why some objects look brighter than others, and what brightness tells us about these astronomical objects. 


Visit The Universe Adventure and read the top section, entitled Apparent Magnitude. Answer these questions based on your reading. You can record your answers on the Star Light student sheet.

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

Now read the second section, entitled The Relation Between Brightness and Luminosity.

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

Exactly how far is a light-year? Visit EarthSky and read the section, entitled How Far Is a Light-Year? Answer these questions based on your reading:

  • 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? 

Knowledge Check

Using your mobile device, you should develop a short video to document how you might explain magnitude, luminosity, and brightness of stars within a constellation that interests you. Some of the points you should address include:

  • Name of constellation
  • Mythology/cultural significance of the constellation (e.g., Greek, Native American, Islamic)
  • Major stars of the constellation
  • Discussion of magnitude, luminosity, and brightness, with reference to the major stars
  • An interesting story about the constellation or one of the astronomical objects in it

A variety of different apps can be utilized to produce these short videos, including iMovie, Animation HD, Explain Everything, Show Me, Comic Life, or others. View Stargazing Basics 2: Understanding Magnitudes in the media player above to see an example of a five-minute educational video. 

This esheet is a part of the Star Light, Star Bright lesson.

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