It is the only moon with a substantial atmosphere, exceeding in mass the atmosphere of Earth.

In the absence of a substantial atmosphere, the two objects fell and hit the moon's surface at the same time.

It is the only moon in the solar system with substantial atmosphere.

"It has a substantial atmosphere," he said.

Its substantial atmosphere, like Earth's, is thick with nitrogen, though it has no free oxygen.

The puzzle: How can an object "with far less mass than Earth's moon" retain a "very substantial" atmosphere?

Due to its small size (and thus its small gravity), Mercury has no substantial atmosphere.

The lack of a substantial atmosphere for insulation results in temperature extremes and makes the Moon's surface conditions somewhat like a deep space vacuum.

Dunes can likely be found in any environment where there is a substantial atmosphere, winds, and dust to be blown.

They also believed that Mars had a relatively substantial atmosphere.