Arcturus, the brightest star in the constellation Botes and one of the brightest stars in the night sky. Arcturus is a giant orange-colored star with a diameter about 25 times that of the sun. The surface temperature of Arcturus is only 7,000 F. (3,870 C.), some 3,000 F. (1,670 C.) less than the sun's surface temperature. Because of its size, however, Arcturus gives off more than 100 times as much light and heat as the sun. Arcturus is approximately 36 light-years from the earth. It has an apparent magnitude of -0.1 and an absolute magnitude of -0.3.
Hundred of meteors fly across the sky every night, but only a few make it to Earth. Meteors are best known for the brilliant streaks of light they make as they burn up in the atmosphere. Learn about 10 memorable meteor crashes that left an impression.
We know it's not made of green cheese, but what are the origins of the moon? Learn astronomers' theories about where the moon came from.