Mercury
Terrestrial Planet
Mercury is the smallest and innermost planet in the solar system, a cratered, airless world that swings from 430°C in direct daylight to -180°C at night. Despite being closest to the Sun, it is not the hottest planet — that title belongs to Venus.
Field Notes
- A single day on Mercury (sunrise to sunrise) lasts about 176 Earth days — longer than its 88-day year.
- It has no meaningful atmosphere to trap heat, which is why its temperature swings so violently between day and night.
- Mercury's surface closely resembles the Moon's, covered in impact craters billions of years old.
| Planet Specifications | |
|---|---|
| Radius | 2,439 km |
| Mass | 3.301 × 10²³ kg |
| Distance from Sun | 57.9M km |
| Rotation Speed | 10.89 km/h |