A day longer than its year. A day on Mercury lasts longer than its year: the Sun takes 176 Earth days to come round again, and the planet goes round the Sun in 88.
Across
4,880 km
Surface
74.8 million km²
A day
176 Earth days
A year
88 Earth days
From the Sun
58 million km
Gravity
0.38 × the Earth’s
Temperature
167 °C
Moons
0
What you’re seeing
MESSENGER’s colour map of the whole planet, stitched from thousands of photos taken from orbit between 2011 and 2015.
Named places
Caloris Planitia: The biggest impact basin on Mercury, 1,500 km across. The blow that made it sent shock waves right through the planet, leaving jumbled hills on the far side.
Rembrandt: A basin 716 km across, found by MESSENGER as it flew past in 2008: one of the youngest of Mercury’s great basins.
Beethoven: One of Mercury’s largest basins, 630 km across, its floor long ago filled by lava. Like most of Mercury’s craters, it is named after an artist: here, a composer.
Tolstoj: An ancient basin 355 km across, one of the oldest on Mercury that can still be made out.
Rachmaninoff: A double-ringed basin 305 km across. The smooth ground inside its inner ring is some of the youngest lava on the planet.
Raditladi: A ringed basin 258 km across, young enough that few craters have landed on it since.
Hokusai: A young crater 114 km across. The bright rays of rock it threw out stretch for thousands of kilometres across the north.
Kuiper: A bright young crater with rays, named after Gerard Kuiper, an astronomer on the team of Mariner 10, which flew past in 1974 and 1975.
Prokofiev: Ice on the planet nearest the Sun: the floor of this crater near the north pole never sees sunlight, and radar finds water ice there.
Borealis Planitia: Wide northern plains of old lava, 3,450 km across, that flooded and buried the craters beneath them.
Enterprise Rupes: A cliff 820 km long and up to 3 km high. Mercury shrank as its iron heart cooled, and its crust wrinkled into cliffs like this one.
MESSENGER’s end: After four years mapping Mercury from orbit, MESSENGER ran out of fuel and came down here, near Janáček crater, making a new crater of its own.
USGS Astrogeology, MESSENGER MDIS colour basemap, public domain.