For the planets that have atmospheres (mixtures of gases surrounding the surface of a planet), the average temperature stays relatively constant because the atmosphere acts as a type of insulator. These planets have only small variations in the temperature when a section of the planet faces away from the sun. Mercury, on the other hand, with no atmosphere and an elliptical orbit has very large differences. In the table below the temperatures of Mercury, Venus, Earth, and Mars are taken on the planetary surface, while those of Jupiter, Saturn, Uranus, and Neptune are taken at the tops of the clouds, there being no solid surface on these planets.
| Planet |
Temperature Range (°C) |
| Mercury |
–184 to 420 |
| Venus |
427 |
| Earth |
–55 to 55 |
| Mars |
–152 to 20 |
| Jupiter |
–163 to -123 |
| Saturn |
–178 |
| Uranus |
–215 |
| Neptune |
–217 |
This plasma lamp—an apparatus you often see at science fairs and novelty shops—emits streams of plasma, electrically charged particles that are found in everything from stars to television displays and fluorescent lights.
