Which Terrestrial Planets Are Geologically Active?

Additionally, this fact explains why the Earth and Venus are still geologically active worlds with relatively thick atmospheres (for terrestrial worlds, Table ). Atmosphere's are formed and maintained by volcanic outgassing. Mercury and Earth's moon have been geologically dead for billions of years.

Which of the terrestrial planets is geologically dead?

Mercury and the Moon, similar in size and appearance, are both geologically dead because of their relatively small size.

Do terrestrial planets have geological activity?

Three of the four solar terrestrial planets (Venus, Earth, and Mars) have substantial atmospheres; all have impact craters and tectonic surface features such as rift valleys and volcanoes.