Betelgeuse, a bright reddish star in the constellation Orion. It is about 495 light-years from the earth, though some measurements put it at about 640 light-years away. Its color indicates a relatively low surface temperature of about 5,000° F. (2,800° C.), about half that of the sun. Betelgeuse is a variable star that fluctuates irregularly in size and brightness. At its smallest, Betelgeuse has a diameter some 300 times that of the sun; its greatest diameter is about one-third larger than this. Betelgeuse is classified in the group of largest known stars, the supergiants.
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.
Scientists have discovered the existence of water on both our moon and on Mars. Both findings are significant, but what do they mean? Can we use this information to our advantage for space exploration?