Each year around Nov. 17-18 the Leonid meteor shower peaks, offering up several shooting stars an hour. In some years there are dramatic bursts in which many meteors rain down every minute. Learn what's behind this fickle show.
MAVEN will make detailed measurements of Mars' atmosphere from orbit, helping scientists understand how Mars' climate has changed so dramatically over the last few billion years. Here are some key facts to keep in mind about MAVEN and its mission.