By Karla Lant
New research shows that our Moon had an atmosphere 3 to 4 billion years ago.
It formed when volcanic eruptions rocked the ancient satellite, propelling gases above its surface too rapidly for them to seep into space.
The surface of the Moon is peppered with impact basins filled with volcanic basalt. These basalt plains, called maria, were formed when plumes of magma from inside the Moon erupted to the surface, creating lava flows.
Astronauts from the Apollo missions brought back samples from the maria to Earth, and we now know that the lava flows contained carbon monoxide and other gas components, sulfur, and even the building blocks of water.
Our Moon has no atmosphere now, as it lacks a strong enough magnetic field and sufficient mass to hold an atmosphere around it.
