Mercury
Mercury
Planet · 0.39 AU from the Sun
Mercury facts
- Type
- Planet
- Distance from the Sun
- 0.39 AU (5.79 × 10⁷ km)
- Orbital period (year)
- 88 Earth days
- Diameter
- 4,879 km
- Mass
- 3.3 × 10²³ kg
- Moons
- 0
- Rotation period (day)
- 58.6 Earth days
- Axial tilt
- 0.034°
- Mean temperature
- 167 °C
- Discovered
- Known to the ancients
Orbit
About Mercury
Mercury is the smallest planet and the closest to the Sun, racing around it in just 88 days. With almost no atmosphere it swings between scorching days and freezing nights, and its cratered, airless surface looks much like our Moon.
- Named after the Roman messenger god
- Discovered: Known to the ancients
Mercury: frequently asked questions
- What is Mercury?
- Mercury is a planet in our Solar System, orbiting the Sun at an average distance of 0.39 AU (5.79 × 10⁷ km). Mercury is the smallest planet and the closest to the Sun, racing around it in just 88 days.
- How far is Mercury from the Sun?
- Mercury orbits the Sun at an average distance of 0.39 AU, about 5.79 × 10⁷ km. One AU is the Earth-Sun distance, so Mercury is roughly 0.39 of Earth's distance from the Sun.
- How long is a year on Mercury?
- Mercury takes 88 Earth days to complete one orbit of the Sun, which is one Mercury year. By Kepler's third law, bodies farther from the Sun take longer to go around.
- How many moons does Mercury have?
- Mercury has no moons.
- How big is Mercury?
- Mercury has a diameter of about 4,879 km and a mass of roughly 3.3 × 10²³ kg.
See Mercury in motion
Data from NASA/JPL and NSSDCA. Source.