Comets Leave Dust Cloud Around the Moon

Earth’s moon is wrapped in a permanent cloud of dust, similar to what has been found around the icy moons of Jupiter and Saturn, new research shows.

The moon’s cloud stems from impacts of fast-moving dust particles shed by highly eccentric comets, physicist Mihaly Horanyi, with the University of Colorado Boulder, and colleagues write in this week’s Nature.

The cloud grows denser during annual meteor showers, particularly the Geminids, the authors note.

Scientists used NASA’s now-defunct Lunar Atmosphere and Dust Environment Explorer, or LADEE, to detect dust particles striking the spacecraft as it circled the moon at altitudes ranging from about 13 miles to about 62 miles above the surface.

Between October 2013 and April 2014, LADEE’s Lunar Dust Experiment detected about 140,000 dust hits during about 80 days of cumulative observation time.

The researchers discovered that the moon’s cloud is asymmetrical, a contrast to the roughly spherically symmetric clouds found around Jupiter’s icy moons. They suspect Jupiter’s powerful gravity tempers the orbits of bombarding interplanetary dust particles.

“The dust production on the lunar surface is dominated by particles of cometary origin, as opposed to slower asteroidal dust particles, which follow near-circular orbits as they migrate toward the sun,” the scientists wrote.

“We expect all airless planetary objects to be immersed in similar tenuous clouds of dust,” they added.

From Discovery News