Scientists discover ‘permanent’ dust cloud around Moon


Fazanavard فضانورد
Apr 5, 2015
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18 Jun, 2015

There is a permanent, but asymmetric dust cloud surrounding the Moon, created by tiny dust grains lifted up from the lunar surface, scientists have found. Its density may increase during annual meteor showers such as, for example, Geminid.

According to scientists from, the cloud is comprised of dust grains swept up by other high-speed, interplanetary particles passing by, often in the wake of comets.

Many of the dust particles are traveling at thousands of miles per hour in the opposite orbital direction of the solar system’s planets, causing high-speed, near head-on collisions with the moon’s leading surface, said Professor Mihali Horanyi.

According to Horanyi, even a single dust particle from a comet striking the moon can excite thousands of smaller particles on the surface. An event of this sort makes the dust hang in the airless environment for days.

The lunar cloud was detected using NASA data from the Lunar Atmosphere and Dust Environment Explorer (LADEE), which was sent up in 2013 to orbit the moon for six months. An onboard detector, built in Boulder Colorodo, recorded over 140,000 impacts with the Moon’s surface in that period.

Scientists have noticed that this rustling up of particles comes every December with the arrival of the Geminid shower, just as Earth passes through a cloud of space debris.

This is when the dust cloud around the moon is especially thick.

“When these ‘beams’ we see from meteors at night hit the moon at the right time and place, we see the cloud density above the Moon skyrocket for a few days,” said Horanyi.

The discovery of this permanent cloud, according to Horanyi, “is a nice gift from the mission.”

“We can carry these findings over to studies of other airless planetary objects like the moons of other planets and asteroids,” Horanyi said.

The findings appear in a study in the June 17 issue of the journal Nature.

For Horanyi, the discovery has practical implications. Dust travels at ultra-high speeds and has been known to damage spacecraft and space suits. Being able to predict its course and timing can better prepare humanity for future space missions.

The lunar dust cloud was first theorized in the 1960s, with the aid of unmanned moon landers. Several years later, an Apollo mission orbiting the rock saw a distinct glowing disk too bright to have been illuminated by the Sun. The glow was determined to have come from the Moon itself.

As the latest findings from LADEE did not match the Apollo astronauts’ reports of a thicker, higher dust cloud, Horanyi assumes that conditions may have been different back then. Horanyi will be keeping a close eye on the New Horizons mission that is scheduled to reach Pluto by July 14. He is the principle research scientist for the dust-counting instrument on that space craft.

A permanent, asymmetric dust cloud around the Moon

17 June 2015

Interplanetary dust particles hit the surfaces of airless bodies in the Solar System, generating charged1 and neutral2 gas clouds, as well as secondary ejecta dust particles3. Gravitationally bound ejecta clouds that form dust exospheres were recognized by in situ dust instruments around the icy moons of Jupiter4 and Saturn5, but have hitherto not been observed near bodies with refractory regolith surfaces. High-altitude Apollo 15 and 17 observations of a ‘horizon glow’ indicated a putative population of high-density small dust particles near the lunar terminators6, 7, although later orbital observations8, 9 yielded upper limits on the abundance of such particles that were a factor of about 104 lower than that necessary to produce the Apollo results. Here we report observations of a permanent, asymmetric dust cloud around the Moon, caused by impacts of high-speed cometary dust particles on eccentric orbits, as opposed to particles of asteroidal origin following near-circular paths striking the Moon at lower speeds. The density of the lunar ejecta cloud increases during the annual meteor showers, especially the Geminids, because the lunar surface is exposed to the same stream of interplanetary dust particles. We expect all airless planetary objects to be immersed in similar tenuous clouds of dust.