Planet
The smallest planet and closest to the Sun, with no atmosphere to retain heat.
| Type | Planet |
|---|---|
| Distance from the Sun | 0.39 AU |
| Diameter | 4,879 km |
| Mass | 3.30 × 10²³ kg |
| Surface gravity | 3.7 m/s² |
| Temperature | 67°C |
| Moons | 0 |
| Rings | No |
| Orbital period | 88 days |
| Rotation period | 1,408 hours |
| Apparent magnitude | -0.4 |
| Redshift | 0 |
| Discovered | Prehistoric |
Planets are massive enough to pull themselves round and to have cleared their orbit of other debris — the second part is the line the solar system's dwarf planets fall short of.
At 4,879 km across, Mercury is 38 percent of the diameter of Earth.
Its mass is 5.5 percent of the mass of Earth.
It keeps an average distance of 0.39 AU from the Sun, so sunlight takes 3 minutes to reach it.
A single orbit takes 88 days.
An average temperature of 340 K works out at 67 degrees Celsius, warmer than the 15 degrees Earth averages.
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