Mercury
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Mercury can be seen in the evening close to where the Sun sets and in the morning where the Sun rises. Mercury is the closest planet to the Sun. The distance between Mercury and the Sun is 0.4 AU. Its diameter is 1524 miles. It orbits the Sun once every 58.65 days. A year on Mercury is 88 days. Mercury was named after the Roman god Mercury who was the messenger of the gods. The Teutonic people named this for their Woden. Wednesday or Wodnesdaeg in Anglo-Saxon, is another name. The temperature by day is 800°F and at night it is -300°F. Mercury's atmosphere is so thin that it's barely detectable. Mercury's mass is 0.055 earth masses. Mercury does not have any moons.
Structure:
http://www.astro.uni.wroc.pl/vt-2004/mt-2003/mt-mercury-history.html
Mercury has a very large core. It is composed of iron some of which is hot and fluid. It has a radius between 1,800-1,900 Km. The core makes up 75% of the mass and 42% of the volume.
Mercury's thin mantle is mainly a rocky silicate. it is between 400-500Km thick.
Mercury's surface is covered by numerous craters and lobed ridges. Its poles are permanently frozen and there might be a chance of water existing. The craters were formed when meteors came and hit Mercury. Mercury's surface is made of silicate. The crust and mantle together have a thickness of about 100km. Mercury does not have any tectonic activity.
Mercury's atmosphere is
very thin. It contains 42% molecular
oxygen, 29.0%
sodium, 22.0%
hydrogen, 6.0%
helium, 0.5%
potassium, and
small amounts of
argon,
nitrogen,
carbon dioxide,
water vapor,
xenon,
krypton, and
neon