Unlike our sun, many stars are part of binary systems in which two stars orbit a common center of gravity. We can't always see the individual stars, but we can learn about them by analyzing the light they produce. If the stars eclipse each other, the total brightness of the system changes in a regular pattern. The pattern depends on the sizes and luminosity of the stars and the alignment of their orbit to our line of sight.

These animations show a binary star system viewed from three different angles. The graphs show the total brightness of the system over time.

  !   Click any diagram to see the animations. Use the movie controls to compare the three views.