Planet Mercury Facts
Image taken by the NASA probe Messenger on its approach to Mercury.
- Mercury is the planet nearest the sun. It has a diameter of only 3,032 miles (4,879 km), around 40% of Earth's diameter.
- The planet orbits the sun at an average distance of around 36 million miles (58 million km), compared with 93 million miles (150 million kilometers) for Earth.
- Mercury is the smallest planet in the solar system, Jupiter's moon Ganymede and Saturn's moon Titan are also both larger in diameter.
- Mercury orbits the sun faster than any other planet, taking only 88 days to make one complete orbit.
- The planet rotates on its axis extremely slowly, taking 59 days compared to Earth's 24 hours.
- The sun appears around two and a half times larger in its sky compared to how we see the sun on Earth.
- Despite incredibly warm surface temperatures water ice exists in the permanently shadowed parts of craters in Mercury's north polar region.
- NASA's Messenger spacecraft crash landed into Mercury after running out of fuel in April 2015, it surveyed the planet over a four year period gathering new data.
- Mercury is usually very difficult to see in the night sky with the naked eye.
Strange looking crater imaged by Messenger.
Mercury's SurfaceThe planet's colorless and cratered surface gives it a similar appearance to the moon, indeed like the moon it is covered in fine dust particles, between the craters there are smooth plains, mountains and valleys.
Mercury's AtmosphereThe planet has very little atmosphere, only tiny amounts of helium, hydrogen, oxygen and sodium. Because of the lack of atmosphere Mercury's sky is black with stars being visible during the day.
Mercury's TemperatureMercury's lack of atmosphere leaves it unprotected from the sun's rays. The temperature on the planet may reach 450C (840F) during the day but at night the temperature may drop as low as -170C (-275F).
MoonsMercury has no moons.
Life on MercuryIt is improbable that any form of life could exist in the harsh conditions.
Origin of NameThe Romans named the planet after the messenger to the gods.
Is Mercury Just Like the Moon?
The cratered surface of Mercury.