Mercury is the innermost and smallest 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; its greatest angular separation from the Sun (greatest elongation) is only 28.3° (it can only be seen in twilight).
Comparatively little is known about the planet: the only spacecraft to approach Mercury was Mariner 10 from 1974 to 1975, which mapped only 40 to 45 percent of the planet's surface.
Physically, Mercury is similar in appearance to the Moon as it is heavily cratered.
It has no natural satellites and no substantial atmosphere.
The planet has a large iron core which generates a magnetic field about 1 percent as strong as that of the Earth.
Surface temperatures on Mercury range from about 90 to 700 K (-180 to 430°C) , with the subsolar point being the hottest and the bottoms of craters near the poles being the coldest.
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Precession Precession refers to a change in the direction of the axis of a rotating object. In certain contexts, "precession" may refer to the precession that ... >
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Saturn Saturn is the sixth planet from the Sun. It is a gas giant, the second-largest planet in the solar system after Jupiter. Saturn has a prominent ... >
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Uranus Uranus is the seventh planet from the Sun. It is a gas giant, the third largest by diameter and fourth largest by mass. NASA's Voyager 2 is the only ... >
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Neptune Neptune is the eighth and outermost planet in our solar system. It is the fourth-largest planet by diameter and the third-largest by mass; Neptune is ... >
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Jupiter Jupiter is the fifth planet from the Sun and by far the largest within the solar system. Jupiter is usually the fourth brightest object in the sky ... >
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Dysnomia (moon of Eris) Dysnomia, is a moon of the dwarf planet Eris. The satellite is about 60 times fainter than Eris, and its diameter is estimated to be approximately ... >
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