The planet Mercury is the closest planet to the sun of all nine planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto). Its diameter is 3,032 miles. Its average distance from the sun is about 36 million miles. It comes as close as about 28,580,000 miles from the sun. The farthest Mercury gets from the sun is about 43,380,000 miles from the sun. Mercury’s speed is about 30 miles per second, faster than any of the other planets. It orbits the earth once every 87.969 days.
Mercury rotates on its axis once every 59 days. Earth’s rotation is 24 hours, that is why one day is 24 hours long. Mercury’s rotation was a surprise, it was thought before the radar studies of the planet in 1965 that Mercury rotated on its axis about the same length of time as it takes to orbit the sun (87.969 days). This would make one side of the planet face the sun and the other side always face away from the sun. This caused astronomers to believe that Mercury is hot on the side that always faces the sun and cold on the side that always faces away from the sun.
Mercury has plains, cliffs, and craters similar to those of the moon. The craters are formed when meteors and small comets hit its surface about 4.6 billion years ago. Silicates cover Mercury in a thin layer. Mercury’s largest crater is the Caloris Basin; it is 800 miles in diameter. The basin is the result of an impact that was so great that it caused lava eruptions. Several other large impact basins have been found. One of these is the Tolstoj crater, located in the location 16.3 degrees south latitude and 165 degrees west longitude. It was named after Leo Tolstoy, the Russian author of War And Peace.
Another large crater is Beethoven, located in the location 20 degrees south latitude and 124 degrees west longitude. Mercury is dry and extremely hot. Its atmosphere has traces of helium. hydrogen, oxygen, and sodium. The size of the Sun in the sky is 2 ½ times as large as it is on the Earth. The iron core of Mercury generates a magnetic field about one percent that of Earth’s.
Temperatures on Mercury range from 183 degrees celsius below zero to 427 degrees celsius. It is one of the terrestrial planets (Mercury, Venus, Earth, and Mars). All terrestrial planets have silicate rock and are similar to earth. With an equatorial radius of 2,439.7 kilometers, it is the smallest planet in the solar system (just a little bigger than Pluto). Mercury is smaller than one of the moons of Jupiter (Ganymede) and one of the moons of Saturn (Titan).
The National Aeronautics And Space Administration (NASA) sent the spacecraft Messenger in August 2004 to Mercury. It was the first one to enter Mercury’s orbit on March 17, 2011. Messenger stands for Mercury Surface, Space Environment, Geochemistry, and Ranging. It has circled the Sun fifteen times and made one flyby of the earth, two flybys of Venus, and three flybys of Mercury. It took pictures of each planet for scientific study.
After three months of taking pictures of Mercury, Messenger has discovered many new facts about the planet Mercury’s surface. Its surface composition, topography, and magnetic field have been magnified with the thousands of pictures it took.