Solar system · Mercury

Where is Mercury right now?

Mercury, grey and covered in craters, drawn from its maps in Exo-View

Mercury is the smallest planet and the nearest to the Sun, going round it in just 88 days, faster than any other. It is hard to see, always close to the Sun in the sky, but Exo-View shows where it is at this moment and lets you fly out to it.

Fly to Mercury See every planet

Orbit: 88 days
Distance from the Sun: 0.39 AU on average, from 0.31 to 0.47
Width: 4,879 km, a little over a third of the Earth's
Spin: Once in 58.6 days
Day: From one sunrise to the next takes 176 Earth days, two of its years
Temperature: About 430 °C by day, about −180 °C by night
Moons: None

A day longer than a year

Mercury spins three times for every two trips round the Sun. Together with its fast orbit, that makes the Sun take 176 Earth days to get from one noon to the next, twice its year. With almost no air to hold the heat, the sunlit side bakes and the night side freezes.

Ice at the poles

Although it is the nearest planet to the Sun, Mercury has water ice. In craters at its poles, where the Sun never shines, it stays cold enough for ice to last for billions of years, which NASA's MESSENGER spacecraft, in orbit round the planet from 2011 to 2015, confirmed. The planet is also strangely dense, with a huge iron core, wider than our Moon, taking up most of its inside. A European–Japanese craft, BepiColombo, is on its way to study it further.

Seeing it

Mercury is never more than about 28° from the Sun, so it can be seen only low in the west just after sunset or low in the east just before sunrise, for a few weeks at a time, as a bright, steady point. It is easier to find in the spring evenings or the autumn mornings in the north, when the angle of the ecliptic to the horizon is steepest.

In Exo-View

The button below flies from the Sun to Mercury, drawn from its maps. Run the clock forward to see how fast it laps the Sun, and how it appears first on one side of the Earth's sky, then the other.