What Is the Average Temperature of Mercury?

The average temperature on the planet Mercury, named after the swift and winged-footed messenger of the gods, is 350 degrees Fahrenheit. This, of course, is incredibly hot but that's not the half of it, literally. Read further and see why Mercury is the hottest planet that we have in our solar system and one of the coldest as well.

Time Frame

One of the obvious reasons that Mercury is so hot is because of its proximity to the sun. It is the closest planet to the sun in the entire solar system, with an average distance of 36 million miles. Another is that Mercury rotates once on its axis every 59 days. This means that for every three times Mercury has orbited the star it has rotated completely just twice. This slow rotation means that the surface of Mercury gets prolonged exposure to the sun's rays, which bake it like an oven.

Effects

Mercury has an atmosphere that can best be described as a vacuum. What few molecules of gases there are are always being lost out into space, being replaced by the solar winds from the sun. With no air to give Mercury some sort of protective layer from the direct sunlight, the temperature rises to extreme heights. It is believed that it can get as scorching as 800 degrees on the planet's surface. Ironically, the lack of air combined with the agonizingly slow rotation of the planet compared to others in the solar system combine to make the dark side of Mercury (the nighttime side) an incredible -300 degrees Fahrenheit.

Significance

This wild roller coaster ride of temperatures makes Mercury the planet with the largest temperature range in the solar system. Venus has an atmosphere and rotates rapidly, so even though it can achieve very high temperature readings they are constantly hot. Mars and the planets beyond Earth's orbit are cold and frozen worlds, with no heat to speak of. Only Mercury has such a wide gap between its planetary highs and lows, an astounding figure of over one thousand degrees Fahrenheit.

Potential

The planet, second smallest in the solar system, has been visited by only two spacecraft from Earth. One was Mariner 10 in 1974, which flew by Mercury a trio of times and was able to map less than half of its surface. The Messenger spacecraft was launched by NASA to go to Mercury in 2004 and it will hopefully be able to transmit better pictures of the planet beginning in 2011.

Misconceptions

Astronomers used to believe that Mercury took the same length of time to rotate on its axis as it took to orbit the s. This meant that Mercury was thought to always have the same side facing the sun. Such a scenario would result in one side constantly being baked while the other side was frozen. But Doppler radar observations made in 1965 disproved that idea, showing the 3 to 2 ratio of revolutions on its axis to orbits of the sun that we now know occurs.

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