In astronomical terms, Mercury is the closest planet to our solar system's sun. As such, it moves around the sun faster than any other planet in the system in what is known as an eccentric orbit. About Mercury The speed at which this planet moved across the sky at night was noted by ancient Roman astronomers, who subsequently named it after their swift-footed messenger god (which is why it is often referred to as the ‘planet of communication’ in astrology). Until NASA's Messenger space probe reached and completely mapped this rather elusive planet before impacting on its surface in April 2015, very little was known about it. Today, we know that this celestial body is far more dynamic and complex than its eccentricity and swiftness previously allowed us to discover. Mercury in Astrology mercury Every astrological sign has a planetary ruler, and most ruling planets reign over a single sign. Mercury, however, is the planetary ruler of both Gemini and Virgo, making it one of only two planets that divide their attention between two signs (Venus, which reigns over Libra and Taurus, being the other one). Mercury's Rule There are some basic similarities in the way Mercury rules over Gemini and Virgo. People born under both of these signs are, for instance, exceptionally intelligent. They can also be very flexible and capable of 'changing like the wind', although this is mostly due to the fact that both Gemini and Virgo have a 'mutable quality'.