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The Moon is cloaked in a constant, asymmetric cloud of dust, Nasa scientists have discovered -- and it's likely that the cloud is caused by passing comets.
Data from Nasa's Lunar Atmosphere and Dust Environment Explorer (LADEE), published in a report in Nature, revealed that a dust cloud persistently hangs around the Moon, generated by high-speed comet particles crashing into it. These particles then kick dust up from the lunar surface into space, resulting in the eerie shroud.
While it's odd enough for any type of cloud to be found around an airless body in the solar system, Nasa astronauts first spotted an odd "horizon glow" around our nearest neighbour in space during the 70s Apollo 15 and 17 missions. The latest observations suggest that around 120kg of dust cloaks the Moon at any one time, with the cosmic dust rising as far as 100km above the surface before settling down again.
The researchers captured the data by using the LADEE's LDEX instrument, which caught the dust over a six-month period as it flew between altitudes of 20 and 100km. Mihály Horányi, a physics professor at the University of Colorado Boulder, commented: "LADEE was the first mission to carry a dedicated dust instrument in low-altitude orbit. All other attempts were either remote sensing imaging -- struggling with line-of-sight issues."
He continued: "The cloud we identified is comprised of bigger particles and their density is so low that this cloud could not have been noticed by the astronauts."
As a result of the new findings, it's now possible that all airless satellites in space -- including Mars' moons -- are wrapped in dust clouds, caused by particles from the Kuiper belt: the disc-shaped region of icy objects that lies at the edge of the Solar System.
However, the strange glow first spotted on the Apollo missions is still yet to be explained. It's possible that light scattering -- when sunlight hits tiny dust particles, causing it to brightly scatter in various directions -- or electrostatic forces may have been the culprits. But until humans head back to the Moon again, it's likely to remain a mystery.
This article was originally published by WIRED UK
