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A Day On Mercury

The apparent path of the Sun in Mercury's sky is strange compared to what we see from Earth. This is because a solar day - noon of one day until noon of the next - is two Mercury years (176 Earth days) long. From Mercury, the Sun would appear 2 to 3 times larger than it does from Earth, and it varies in size because Mercury's orbit is highly eccentric (far from circular).

Mariner 10 Photomosaics

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These two photomosaics were each made from pictures transmitted to Earth during the first encounter of Mariner 10 on March 29, 1974. They show a planet which appears much like Earth's Moon, with several subtle but important differences. Whereas the Moon has its smooth plains concentrated on the side facing Earth, Mercury's surface has numerous patches of plains interspersed between craters. Numerous craters with bright "rays" can be seen distinctly under the direct sun illumination angle at which these pictures were taken.

Mercury Facts || Earth-based Views || A Day On Mercury
Surface Of Mercury || Mariner 10 Encounters

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1998 National Air and Space Museum