Mars Enters Retrograde

On Saturday, December 7, Mars’ easterly orbital motion through the stars of Cancer will slow to a stop in order for it to begin a westerly retrograde loop that will last through its mid-January opposition and into late February. Tonight the bright, reddish dot of Mars will be positioned in the eastern evening sky in Cancer, just above the large Beehive Cluster and below the bright “twin” stars of Gemini, Castor and Pollux. Over the coming weeks, you can watch Mars travel upwards (celestial west) towards those stars. Retrograde loops occur when Earth, on a faster orbit closer to the sun, passes more distant solar system objects “on the inside track”, making them appear to move backwards across the stars for a while. Mars’ loop will cover almost two fist widths, or 19 degrees of the celestial sphere.