MARS IS GOING RETROGRADE: Today, Mars stopped moving among the stars, reversed course, and started going the other way. Astronomers call this "retrograde motion," and it's a sign that Earth and Mars are about to have a close encounter. Get the full story with sky maps and observing tips on Spaceweather.com.
Aurora alerts: Sign up for Space Weather Alerts and receive a text message when auroras appear in your area.
Above: The retrograde motion of Mars depicted by graphic artist Larry Koehn of ShadowandSubstance.com
