Ursa Minor, or Little Bear, the constellation of the northern sky that contains the Little Dipper. Ursa Minor is the most northerly of all constellations. Its brightest starPolaris, or the North Staris within approximately one degree of the north celestial pole. Because of this, Polaris never sets in latitudes north of the Equator, and is therefore visible in the Northern Hemisphere sky on any clear night. The second and third brightest stars, forming the end of the Little Dipper's bowl, are called the Guardians of the Pole.
A billion years ago, the moon stopped being geologically active. But that's not to say that the moon is doing nothing for us. Let's find out why we owe our moon some thank-yous.
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.