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.
The moon is often the largest object in the sky outside of the sun. What is the moon made of, how did it form -- and why do people blame it for their strange behavior?
The changing phases of the moon have given us an enduring curiosity about the dark side of the moon. But is there really a dark side of the moon? What would we see there?