Mercury
Planet Mercury, taken by the Messenger space probe. Image courtesy of http://wikipedia.org
Mercury was named for the Roman God, Mercury. He was the fast messenger of the gods. He even had wings on his heels! It is a good name for the planet Mercury because it moves around the sun faster than any other planet. It goes around the sun every 88 days. Even though Mercury goes around the sun very quickly, it spins very slowly on its axis. It takes 58.6 Earth days for Mercury to spin around one time.
Mercury is difficult to study because it is so close to the sun. You can only see it either right before sunrise or right after sunset. The bright light from the sun makes it difficult to study Mercury. It is also very small and hard to see. To help study the planet and take pictures of it, astronomers sent the Mariner 10 to Mercury. It went by Mercury in 1974 and again in 1975 and took many, many pictures as well as measurements. The pictures were sent back to Earth and scientists pieced them together like a giant jigsaw puzzle. Both times Mariner 10 went by Mercury, the same side was facing the sun so these pictures only show half the planet.
Mercury looks kind of like the moon. It has a lot of craters, some of which are up to 800 miles across! Some of these craters have peaks in the middle. There are also wrinkles and large plains on the surface. Its temperature ranges from -292 degrees Fahrenheit and 809 degrees Fahrenheit. Mercury doesn’t have enough gases around it to trap heat from the sun so that’s why Mercury’s temperatures are always swinging so much. With such a thin atmosphere, there is nothing to scatter the rays of the sun. That makes the sky look black all the time, even in the day.
In order to find out even more about Mercury, another unmanned space probe, the Messenger, was sent off in August of 2004. It finally made its first flyby of Mercury in January of 2008. It has already sent back many pictures for scientists to study.
