Mon Prof Augmenté
Mass and Atmospheres
Age 12 · Physics
A planet’s mass pulls gases toward it with gravity. If the planet is too small, its gravity is too weak and gases escape into space.
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In the picture
- Thin gray shell of the smallest planet: almost no gas is held.
- Pale white shell of the second planet: some gas remains.
- Blue shell of the third planet: a strong atmosphere stays.
- Orange-white shell of the largest planet: a heavy atmosphere is held.
Examples
- Earth’s gravity holds the air around us.
- The Moon has too little mass to keep an atmosphere.
Key takeaways
- More mass means stronger gravity, which helps hold gases.
- Low-mass worlds lose their gases to space.
Quiz: Mass and Atmospheres (Age 12)
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What does having more mass do for a planet?
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Why does a planet with low mass lose its gases?
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According to the card, what decides whether a planet can keep an atmosphere?
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