ADDITIONAL CONTRAST OPTICAL DOUBLE STAR INFORMATION:

1. An optical double star is simply two (or more) stars that appear to be in the same direction in the sky. They do NOT revolve around each other like the Earth orbits the sun.

2. This optical double star is special because you can see two different colors. The red (3,000 ºC) or yellow star (6,000 ºC) is cooler than the blue star (20,000 ºC).

3. Often the cooler star will be not only brighter than the hotter star, but also farther away. This can lead into a discussion on how the sizes of stars, along with their temperatures and distances from us, affect how bright they appear to be.

4. Multiple stars, unlike optical double stars, are two or more stars that orbit each other in some fashion.