Capella, one of the brightest stars in the sky, lies 42 light years away in the direction of the constellation Auriga. Its bright yellow appearance indicates that it has a surface temperature similar to that of the Sun. There the similarity ends. It is actually a binary star. Each of the two stars is a giant, with ten times the radius of the Sun. One of the stars has 10,000 times the x-ray luminosity of the solar corona.