Final answer:
The steady escape of gas molecules from the interior of a planet is known as atmospheric leakage. This process occurs when the gas that was trapped in the planet's interior during its formation slowly escapes into space over time.
Step-by-step explanation:
The steady escape of gas molecules from the interior of a planet is known as atmospheric leakage. This process occurs when the gas that was trapped in the planet's interior during its formation slowly escapes into space over time.
Planets like Earth and Mars have experienced atmospheric leakage, resulting in the thin atmospheres we observe today. For example, Earth's original atmosphere may have been formed from debris left over from the formation of the Sun, released through volcanic activity, or derived from impacts by comets and asteroids from the outer parts of the solar system.
Keywords: atmospheric leakage, planet formation, Earth's atmosphere, Mars' atmosphere