The neighbours
Venus is next to Earth. Yet its surface is far hotter than Earth's. A blanket of air is the layer of air around a planet.
Step 1 of 4
- Venus is closer to the Sun, under a thick blanket of air.
- Its surface is fiercely hot.
- Mars is farther from the Sun, under a thin blanket of air.
- Its surface is cold and dry.
The rule
Carbon dioxide is a gas found in air. The greenhouse effect is when gases like carbon dioxide trap heat.
A planet farther from the Sun gets less heat. Farther planets are generally colder. But Venus is the hottest, because its thick air traps heat. Mercury has almost no air. So Mercury cannot trap much heat.
| Planet | What to know |
|---|---|
| Mercury | About 170 °C. Almost no air |
| Venus | About 450 °C. Air is mostly carbon dioxide |
| Earth | About 15 °C. Air and liquid water |
| Mars | Air more than 100 times thinner than Earth's |
Scientists think Mars may once have had liquid water.
Read each clue. Tap the planet.
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