Dust surrounding the Moon

According to a study published in Nature, our natural satellite would be surrounded by a kind of cloud of dust, which is asymmetrical and permanent. The results suggest that the existence of such an exosphere was due to the impact of cometary dust particles that move at high speed on eccentric orbits. This finding supports the hypothesis that all celestial bodies devoid of atmosphere must be immersed in similar, soft clouds of dust.
A cloud of permanent and asymmetrical dust surrounds the moon. It was reported by a group of researchers, led by Mihály Horányi University of Colorado at Boulder, in an article in Nature. The results suggest that this sort of “dust ring” was caused by the impact of cometary dust particles that move at high speed on eccentric orbits, as opposed to particles of asteroidal origin that travel, however, nearly circular orbits affecting our natural satellite with relatively lower speed.

nubi-luna-1Credit: Daniel Morgan and Jamey Szalay

The particles of interplanetary dust arrive on the surface of the celestial bodies devoid of atmosphere resulting in the formation of clouds composed of neutral gas and load and other dust particles. The clouds that arise from this process, forming exosphere dust retained by gravity, have been identified locally by instruments around the icy moons of Jupiter and Saturn. However, they have not yet been observed in the vicinity of those celestial bodies characterized by surfaces regolith refractory.
The first indications of the presence of a cloud of dust near the moon’s surface from the late ’60s when some cameras aboard NASA lander captured a bright glow during a moonrise. Some years later, the observations made at a higher altitude, in particular, by the Apollo astronauts 15:17 reported the existence of a glow even more significant over the lunar horizon during sunrise, a phenomenon that was much more brilliant than it was able to generate the Sun, most likely associated to the existence of a presumed population of minute dust particles and high density which are located in the vicinity of the terminators lunar. Orbital observations successive allowed putting an upper limit on the abundance of such particles of about a factor of 10 lower than that required producing the observations of the Apollo missions. Now, since the new data do not square with the reports of the Apollo astronauts on the presence of a cloud of dust thicker and higher, scientists believe that probably the conditions of that time may have been a little ‘different.
The experiment LDEX (Lunar Dust Experiment) on board the satellite Lunar Atmosphere and Dust Environment Explorer (LADEE) launched in 2013, has registered a total of about 140 000 events during a period of 80 days of observations cumulative. The detector has been designed to explore the clouds of material ejected from the impacts of sporadic interplanetary dust, including any periodic variations in density occur during the meteor streams, and to search for the alleged regions characterized by a higher density of particles of dust above the lunar terminator.
The authors found that the density distribution is not symmetrical spherical but shows a sharp rise near the terminator day between 5 and 7 rooms, slightly tilted towards the Sun due to the direction of motion of the Earth-Moon during a revolution . “Most of the particles of comet dust impacting on the lunar surface traveling with speeds of the order of some thousands of kilometers per hour and in retrograde motion around the sun. This causes the frontal collision, at very high speed, with the powder particles and the the exposed part of the lunar surface as the Earth-Moon system performs a revolution, “says principal investigator Horányi detector LDEX. “This anisotropy reflects the spatial distribution and speed of the bombardment of interplanetary dust particles responsible for the production of clouds of matter ejected into space. Therefore, the identification of this permanent cloud of dust that surrounds the Moon was a kind of gift she gave us this mission, “continues Horányi. “Now we can use these data to study these celestial bodies that are devoid of atmosphere, as the moons of other planets and asteroids.”
This anisotropy, however, is in contrast to the almost isotropic distribution of the dust clouds surrounding the Galilean satellites. Hence the enormous gravitational influence of Jupiter determines effectively a random distribution of orbital parameters related to the bombardment of interplanetary dust particles. However, the asymmetric distribution of lunar material ejected is consistent with current models for the distribution of interplanetary dust in the vicinity of the Earth that consider the local measurements of dust, the observations of the zodiacal cloud in the visible and infrared, as well as the visual observations and radar from ground meteors in the atmosphere.
Therefore, according to the authors, the dust on the moon, dark and sticky which regularly soiled suits of astronauts, would be created mainly by particles of interplanetary dust of cometary origin who continually hit the lunar surface in the course of several billion years, than the dust particles that are slower asteroid following nearly circular orbits as they migrate toward the sun. In addition, the density of lunar material ejected increases during the annual meteor showers, especially that of the Geminids, which has a December when the Earth through a cloud of debris from an object called Phaeton, a cross between an asteroid and a comet. In short, the results of this study seem to indicate that all celestial bodies devoid of atmosphere should be immersed in similar, soft clouds of dust. Then know what they look like space environments where there is dust could have important implications, especially in terms of future human exploration.

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