Mercury (planet)

Mercury

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Mercury is the closest planet to the Sun, and the second-smallest planet in the Solar System. Mercury ranges from −0.4 to 5.5 in apparent magnitude, and its greatest angular separation from the Sun (greatest elongation) is only 28.3°, meaning it is only ever seen in twilight. The planet remains comparatively little-known: the only spacecraft to approach Mercury was Mariner 10 from 1974 to 1975, and only 40–45% of the planet has been mapped.

Related Topics:
Planet - Sun - Solar System - Apparent magnitude - Elongation - Twilight - Spacecraft - Mariner 10 - 1974 - 1975

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Physically, Mercury is similar in appearance to the Moon, being heavily cratered. It has no natural satellites and no atmosphere, but has a large iron core which generates a magnetic field about 1% as strong as the Earth's. Surface temperatures on Mercury range from about 90-700 K, with the subsolar point reaching the hottest temperatures and the bottoms of craters near the poles being the coldest.

Related Topics:
Moon - Cratered - Natural satellite - Atmosphere - Iron - Magnetic field - K - Poles

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The Romans named the planet after the fleet-footed messenger god Mercury, probably for its fast apparent motion in our twilight sky. The astronomical symbol for Mercury (Unicode: {{Unicode|☿}}) is a stylized version of the god's head and winged hat atop his caduceus. Before the 5th century BC, Greek astronomers believed the planet to be two separate objects, and knew it as Hermes when it was visible in the evening sky, but Apollo in the morning sky. Pythagoras was the first to propose that Hermes and Apollo were the same object. The Chinese, Korean and Japanese cultures refer to the planet as the Water Star, based on the Five Elements.

Related Topics:
Romans - God - Mercury - Astronomical symbol - Unicode - Caduceus - 5th century BC - Hermes - Apollo - Pythagoras - Chinese - Korean - Japan - Five Elements

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