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Mercury
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Mercury is named after the Roman messenger of the Gods. Mercury is the
closest planet to the sun. Its size is in-between that of the Earth and the moon. Since it
is close to the sun, it is hard to view. Mercury's cratered surface and lack of atmosphere
closely resembles that of the moon. Even though mercury is close to the sun, it isn't the
hottest planet. It does, however, have the widest range of temperatures -170oC
to 430oC.
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Millions of years ago, a large object stuck Mercury creating an impact
crater called the Caloris Basin. On exactly the opposite side of the planet, there is an
area where the shock waves converge known as the weird terrain.
Mercury is composed mostly of iron. The percentage of iron in the core of the planet gives
evidence that it may have been stuck by a large object in its developmental stages. The
impact would have dislodged the lighter elements of the planet leaving only the heavy
particles. This planet also has curved ridges called Lobate Scarps. These cliffs were
formed during the slow cooling of the molten iron.
Mercury's orbit is an odd rotation around the sun. It rotates one and a half times for
each revolution around the sun. This causes only three days in every two years. Its orbit
is also very elliptical compared to other orbits.
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Distance from Sun:
Mean— 35,980,000 mi.
Shortest— 28,600,000 mi.
Greatest— 43,400,000 mi.
Closest approach to Earth— 57,000,000 mi.
Length of year (earth-days)— 87.97
Average orbital speed— 29.76 mi. per sec.
Diameter at equator— 3,031
Rotation period— 59 earth-days
Tilt of axis "(degrees)— about 0
Temperature— -279 to 801 *F
Atmosphere:
Pressure— 0.00000000003 lb. per sq. in
Gasses— Sodium, Helium, Hydrogen, Oxygen
Mass (Earth=1)— .0.056
Density (g/cubic cm)— 5.42
Gravity (Earth=1)— 0.386
Number of known satellites— 0 |
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[Mercury | Venus | Earth | Mars | Jupiter]
[Saturn | Uranus | Neptune | Pluto]
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