Portal:Astronomy/Featured/October 2006
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Mercury is the innermost planet in the Solar System, orbiting the Sun once every 88 days. It ranges in brightness from about −2.0 to 5.5 in apparent magnitude, but is not easily seen as its greatest angular separation from the Sun (greatest elongation) is only 28.3°, meaning it is only seen in twilight. The planet remains comparatively little known: the only spacecraft to approach Mercury was Mariner 10 from 1974 to 1975, which mapped only 40%–45% of the planet's surface.
Physically, Mercury is similar in appearance to the
atmosphere. The planet has a large iron core which generates a magnetic field about 1% as strong as that of the Earth. Surface temperatures on Mercury range from about 90 to 700 K, with the subsolar point being the hottest and the bottoms of craters near the poles
being the coldest.
The
Five Elements
.
Recently featured:
Fermi Paradox – Definition of planet – Sun
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