Lunar Atmosphere

Public domain info obtained from NASA:

Moon Fact Sheet

http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html

Lunar Atmosphere Diurnal temperature range: >100 K to <400 K (roughly -250 F to +250 F) Total mass of atmosphere: ~25,000 kg Surface pressure (night): 3 x 10-15 bar (2 x 10-12 torr) Abundance at surface: 2 x 105 particles/cm3

Estimated Composition (particles per cubic cm):

Helium 4 (4He) - 40,000
Neon 20 (20Ne) - 40,000
Hydrogen (H2) - 35,000
Argon 40 (40Ar) - 30,000
Neon 22 (22Ne) - 5,000
Argon 36 (36Ar) - 2,000
Methane - 1000
Ammonia - 1000
Carbon Dioxide (CO2) - 1000

Trace Oxygen (O+), Aluminum (Al+), Silicon (Si+) Possible Phosphorus (P+), Sodium (Na+), Magnesium (Mg+)

Composition of the tenuous lunar atmosphere is poorly known and variable, these are estimates of the upper limits of the nighttime ambient atmosphere composition. Daytime levels were difficult to measure due to heating and outgassing of Apollo surface experiments.

Although the Moon is relatively inert geologically, the lunar atmosphere continues to replenished by lunar outgassing events.