Astronomy Picture of the Day
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Each day a different image or photograph of our fascinating universe is
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August 14, 1995
Mercury: Closest Planet to the Sun
This picture was compiled from images
taken by the NASA spacecraft Mariner 10 which flew by the
planet three times in 1974.
Mercury is the closest planet to the
second hottest planet (Venus
gets hotter), and the second smallest planet (Pluto is smaller).
Mercury rotates so slowly that one day there - "day" meaning the
normal time it takes from sunset to sunset - lasts 176 days on
Earth. It is
difficult to see
Mercury not because it is dim but because it always
appears near the Sun, and is therefore only visible for a short time just
after sunset or just before sunrise. Mercury is made of rocky material
like Earth. No one knows why Mercury has the magnetic field that it does.
Tomorrow's picture: Venus: Earth's Sister Planet
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NASA Technical Rep.:
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