Astronomy — The Planet Mercury
- Mercury’s distance from the Sun: 36,000,000 miles
- Length of time for one circuit around the Sun (in Earth days): 88 days
- Length of time for one axial rotation (in Earth days): 59 days, or 2/3 of a solar circuit time
- Diameter: 3000 miles (approximately the same size as our Moon)
- Orbital speed: 108,000 miles per hour (hence, the name Mercury!)
- Surface temperature range: -300 F° to 800 F°
- Atmosphere: Mercury has no atmosphere.
- Mercury is always seen in the general direction of the Sun, never more than 30° from the Sun as we view Mercury from Earth.
- The orbit of Mercury around the Sun is tipped 7° relative to Earth’s plane of orbit around the Sun.
- During Mercury’s formative period, it cooled too quickly to develop mobile plates on a malleable mantle.
- The surface of Mercury has many lobate scarps (long curvi-linear, cliff-like formations).
- Mercury has a large metallic core.
- The Sun’s strong tidal lock on Mercury keeps the planet’s equator pointing directly at the Sun. The equator does not deviate north or south at all.
- Radar scientists think they detected an ice cap at Mercury’s north pole.
Click here to return to the Astronomy index page