Is your planet too cold? Well, it is a sure-fire guarantee that on Mercury, you'll always see a warm front in the local weather forecast. The shuttle transporting you to this planet, which is the first one from the sun, will have specially designed suits for your protection against the heat.

Mercury is one of the four rocky planets and sometimes referred to as one of the four inner planets. Even though it is the closest planet to the Sun, there are sides to Mercury that are extremely cold. Why? The side of Mercury facing the Sun absorbs its heat and can reach temperatures as high as 800 degrees Fahrenheit (430 degrees Celsius). Mercury has a very thin atmosphere which is made up of hydrogen, helium and neon. The atmosphere is not strong enough to trap in the heat, so when that side rotates away from the Sun, temperatures dip as low as 297 degrees Fahrenheit (183 degrees Celsius) below zero. No other planet in this Solar System has that great of temperature fluctuation. (So I suppose you can say you can bring both your summer and winter wardrobes!)

Because Mercury is only 36 million miles from the Sun, the Sun's gravitational pull on Mercury is more than on any other planet. Therefore, Mercury's orbit is not as oval shaped as other planets and looks like a slightly flattened circle. Mercury circles the Sun every 88 days, but rotates on its own axis every 59 days. This means there are a total of three days every two years.

Mercury is a relatively small planet with a diameter at its equator of only 4,878 kilometers, or 3,031 miles. It is the second smallest planet in this solar system, with Pluto being the smallest.

Mercury's surface is very similar to the Earth's moon. Their surfaces are both are gray in color from rocks and soil. They also have many craters created by meteorites hitting its surface. Mercury has rolling hills but almost all are eroded from meteorite showers. Some of the craters on Mercury connect with each other and can be as long as 300 kilometers long. Mercury itself does not have a moon or satellite circling it.

Even though Mercury is the planet closest to the Sun, its sky is very dark. Without a dense atmosphere, there is no prism effect to spread the light. During your stay, you will be able to see Earth and Venus, which appear to be two bright stars in Mercury's dark sky.

There is a magnetic field surrounding Mercury, but it is not very strong. For a long time scientists thought that since the planet was so small, its center core would have solidified long ago. However, with evidence of a magnetic pull, scientists now theorize that there may be a small amount of molten lava bearing iron in its core. Other scientists suspect Mercury's field is due to solar winds.

On November 3, 1973, humans launched their spacecraft, Mariner 10, to Venus. On March 29, 1974, it flew past Mercury at about 705 kilometers (437 miles) from its surface. It returned again on September 21, 1974 and March 16, 1975. During these three visits, humans took 2,700 photographs of 45% of Mercury's surface. To see more about the Earth's space exploration, go to Chronology of Space Exploration.

Life on Mercury has not yet been discovered. So if you decide to visit this planet, you might want to bring along your solar powered televisions and several lengthy books!

Check out other interesting sites about the Mercury:

More links to the Hitchhiker's Guide to the Solar System: