The Moon’s Fragile Atmosphere
The moon orbits the earth with a period of four weeks ( a month) and during the orbit it always has the same side facing the earth. So this means that on the moon there is day and night, but they are both two weeks long instead of 24 hours.
The Moon’s daylight is brighter and harsher than the Earth’s. There is no atmosphere to scatter the light, no clouds to shade it, and no ozone layer to block the sunburning ultraviolet light. However, there is a very, very thin layer of gases on the lunar surface that can almost be called an atmosphere. Technically, it’s considered a surface boundary exosphere.
One of the critical differences between the atmospheres of Earth and the moon is how atmospheric molecules move. Here in the dense atmosphere at the surface of Earth, the molecules’ motion is dominated by collisions between the molecules.The exosphere is so thin that molecules in the lunar exosphere almost never collide with each other. During the lunar night, the Moon’s exosphere mostly falls to the ground. When sunlight returns, the solar wind kicks up new particles to replenish the exosphere.
The intense ultraviolet sunlight kicks electrons off particles in the lunar soil, giving those particles an electric charge that can cause them to levitate. Ambient electric fields lift these charged dust particles as high as kilometers above the surface, forming an important part of the exosphere. Moon dust wrecked havoc with the Apollo spacesuits, which were nearly threadbare by the time they returned to Earth. Levitating dust can get into equipment, spacesuits, and computers, causing damage and shortening the hardware’s useful life. Knowing how much dust is floating around in the exosphere and how it behaves will help engineers design next-generation lunar hardware.
Credit: NASA
