Name two factors which determine whether a planet would have atmosphere or not.

Explanation

To determine whether a planet can have an atmosphere, two key factors are considered:

1. **Surface Temperature**: The surface temperature of a planet affects the kinetic energy of the gas molecules in its atmosphere. If the temperature is too high, gas molecules can gain enough energy to escape the planet's gravitational pull. For example, on planets like Venus, the high surface temperature leads to a thick atmosphere, while on Mars, the lower temperature contributes to a thin atmosphere.

2. **Gravitational Force**: The strength of a planet's gravity is crucial in retaining an atmosphere. A planet with strong gravitational force can hold onto its atmospheric gases more effectively, preventing them from escaping into space. Earth, with its sufficient gravity, retains a stable atmosphere, while smaller celestial bodies like the Moon and Mars, which have weaker gravity, struggle to maintain a significant atmosphere.

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