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The Planet Mercury the Closest Planet to the Sun
What's in a Name?
What Does Mercury's Name Mean?
The name Mercury comes from Roman mythology who in Greek mythology was the god Hermes the messenger of the gods. He is often depicted as wearing winged sandals and is seen delivering messages as he runs. He is also the protector of merchants and travelers.
The Planet Mercury
The Planet Mercury
Mercury is the planet closest to the Sun, It is visible to us on earth in the late evening and early morning sky close to the horizon this is because it is so close to the Sun. It has been called the morning star because it shines so prominently in the early morning before the Sun rises, it shares the name with the evening star for the same reason.
Old Planet Post Card
Did You Know?
Mercury orbits the Sun in an elliptical orbit unlike other planets that have a circular orbit. At times Mercury is closer to the Sun than at other times of the year.
- Because of its proximity to our Sun Mercury developed differently than the other planets. The proto-planetary disc which was full of heavy dust and iron settled in orbit around the Sun and the lighter gasses and ice stretched out to the edge of the solar system. Mars, Earth, Venus, and Mercury are the four major rocky worlds that reside in the inner part of the solar system. Being formed so close to the Sun means that Mercury is made of the heaviest elements. It really is like a large metal ball of iron with a thin crust of silicate. The planet core takes up 75% of the planets volume. It has a think mantle and crust of only 300 miles thick.
- It is scarred with craters. The planet suffered heavy bombardment from comets and asteroids throughout the eons. Since there is no atmosphere (since it is so close to the Sun the solar winds have long ago blown any gasses away from the planet) on Mercury it has no ability to heal from the bombardments since there is no weather on the planet's surface.
- Mercury also has scarps or wrinkles As the planet cooled after forming it shrunk in places, this created the wrinkles. These scarps can reach up to a mile high in areas.
- Mercury's core has not completely cooled and it is believed that it has a semi molten core. Evidence of this is in Mercury's magnetic field. There is no volcanic activity which also heals scarps and impact craters.
- The temperature on Mercury's surface that faces the Sun can reach 800 degrees Fahrenheit, on the night side it can plummet to -300 degrees in shadow. Because there is no atmosphere there is no way to regulate the temperature.
- Because of it's proximity to the Sun Mercury is tidally locked in it's orbit (or nearly so). These tidal forces of the Sun have over the life span of the solar system slowed the rotation of Mercury to match its revolutionary orbit around the Sun. Because of this Mercury rotates very slow. One day on Mercury is 58.5 Earth days in length.
- One year on Mercury is 88 Earth days in length.
- Mercury's orbit is elliptical, when close to the Sun it is only 28.5 million miles or 0.31 AU from the Sun, and at its farthest 43 million miles or 0.46 AU from the Sun.
Mercury's Magnetic Field
Why Does Mercury Have a Magnetic Field?
Mercury has a magnetic field that is only 1 percent as strong as Earth's but it is still strong enough to deflect much of the solar wind. Like Earth's magnetic field the magnetic field of Mercury is tilted. The core of Mercury is a solid iron inner core with a molten outer core. This large iron mass creates a dipole effect which is like an electric dynamo, it almost makes Mercury a large metal world.