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Innermost planet of the Solar System

Proper NameMercury
Orbital Period88 days
Distance from the SunSemi-Major Axis: 57,909,000 km (0.39 AU)
Perihelion: 46,001,000 km (0.31 AU)
Aphelion: 69,817,000 km (0.47 AU)
Rotation Period1,407.5 hours
Diameter4,878 km
Mean Surface Temperature445 K (172°C)
Parent starThe Sun, yellow dwarf star
Other planets in this systemVenus, terrestrial planet
Earth, terrestrial planet
Mars, terrestrial planet
Jupiter, gas giant
Saturn, gas giant
Uranus, ice giant
Neptune, ice giant
Numerous dwarf planets, asteroids and other bodies
NotesA rocky, heavily cratered world, Mercury is the innermost of the Solar System's planets, following an orbit around the Sun at a little more than a third of Earth's distance.
Illustration of Mercury

A view of the barren, cratered world of Mercury.

Size Comparison of Mercury

With a diameter of only 4,876km, Mercury is the smallest of the terrestrial planets - less than half the size of Earth, and scarcely larger than Earth's Moon.

The second smallest of the planets in the Solar System, whose orbit carries it the closest to the Sun. Mercury is a barren, desolate world, not unlike Earth's Moon in general appearance.

Sunrise over Rodin

Sunrise over Rodin, a double crater in the northern hemisphere of Mercury. This image represents the view from within the first, larger crater: the second, deeper crater is also clearly visible.

Map of Mercury
Map of Mercury

Key features on the mapped hemisphere of Mercury.


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