There is not much known about Mercury or its surface, except that it is similar to the moon in appearance and its composition consists of primarily molecular oxygen, sodium and hydrogen. There are also small amounts of h... More »

Mercury's revolution is 88 Earth days. A planet's revolution is the time it takes to make one complete orbit around the sun. This is different than Mercury's rotation period, which is the time it takes this planet to spi... More »

Mercury has a radius of 1,516 miles, an equatorial circumference of 9,525.1 miles and a volume of 14.59 billion cubic miles. Based on radius, Mercury is 0.38 times the size of Earth and is the smallest planet in the sola... More »

Mercury's atmosphere is primarily made up of oxygen, potassium, sodium, helium and hydrogen. The atmosphere on Mercury is made up of atoms that are launched from the planet's surface from micrometeoroid impacts and solar... More » Science Astronomy Planets

During 2014, Mercury was in retrograde for three periods. The dates were February 6 to 28, June 7 to July 1 and October 4 to 25. More » Science Astronomy

The average temperature on Mercury is 332 degrees Fahrenheit. The hottest temperatures on the planet can reach 801 degrees Fahrenheit, and temperatures can drop to as low as -279 degrees Fahrenheit. More » Science Astronomy

In astrology, Mercury in Leo is one of the 12 alignments of the planet Mercury. Those born during this time tend to be confident and often become figures of authority. More » Science Astronomy