20th April 2011 Atmosphere on the Moon

The Moon has a surface boundary exosphere which has somewhere between a few hundred thousanda and a few million molecules per cubic centimetre. This would be considered a good vacuum on Earth.

Dust in the Atmosphere

There has also been dust observed in the atmosphere but how can that be when there isn't enough atmosphere for weather?

• The moon is bombarded with meteorite which kick up dust but there is more in in the atmosphere than this would account for.
• On the day side of the moon, ultraviolet rays are strong enough to displace electrons from surface dust leaving it positively charged. These dust particles repel each other going in the direction possible which is up. This leads to dust plumes. This dust eventually returns to the surface under gravity.

Water on the Moon

Ice has been found in shaded craters, and water molecules in the soil raising the question of whether there is a lunar water cycle.

LADEE Mission

In May 2013, the launch of LADEE (Lunar Atmosphere and Dust Environment Explorer) is planned.  It will sample the moon's exosphere and measure its conditions.

Why care about the Moon's Atmosphere?

In order to understand our own atmosphere, we need to look at other atmospheres. Looking at Venus's atmosphere gave an understanding of the greenhouse effect. Earth is so closely tied to the moon than once a month Earth passes through the Moon's  tail, caused by solar winds, and the Moon passes through the Earth's. What effect does this have? There are many unanswered questions about the Moon's atmosphere but hopefully there will be some answers over the next few years.

Sources

Wikipedia:Moon dust NASA: LADEE mission Wikipedia: Atmosphere of the Moon 365 Days of Astronomy: 20th April 2011 The Moon's Mysterious Exosphere Podcast by Brian Day, NASA Lunar Science Institute