astronomylabMeet the Moon
Terrestrial planet / World 01

Mercury

Small world. Big extremes.

A cratered, rocky world with almost no atmosphere to carry heat from day to night. Mercury races around the Sun while turning slowly on its axis.

Explore this orbit ↗
Mercury, NASA and mission partners

Image: NASA / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington. Processed mission imagery; apparent color varies with filters and processing.

Equatorial diameter4,879 km
One orbit0.24 years
Distance from Sun0.39 AU
Solar day4,222.6 hours

Mercury compared with Earth

Its equatorial diameter is 0.38 times Earth’s. Its mass is 0.06 times Earth’s, while its orbital period is 0.24 Earth years.

The reference gravity is about 3.7 m/s². These rounded values include the reference conventions used in NASA’s fact sheet; the ideal spherical gravity calculator can differ slightly.

NASA reference data ↗

Keep wondering

A few good questions

How far is Mercury from the Sun?

Mercury has a mean orbital distance of about 57.9 million kilometers, or 0.39 AU. Its actual distance varies through its elliptical orbit.

How long is a year on Mercury?

An orbit takes approximately 88 Earth days. The orbit simulator lets you see how distance affects the length of a year.