Have scientists confirmed the dust cloud satellites of the earth?

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Diagram with the Lagrange points of the earthmoon system. If they exist, Kordylewski clouds are in the region of L4 and L5. Image via Wikimedia Commons.

The Royal Astronomical Society (RAS) said this week (October 25, 2018) that astronomers have now confirmed the existence of two elusive dust clouds circling around the orbit of the moon, just like our moon around the moon. They are known as Kordylewski clouds, first reported by and named after the Polish astronomer Kazimierz Kordylewski in 1961. If they exist, the dust cloud satellites of the earth are exceptionally weak, so that their existence is controversial. The RAS points to two new articles about the Kordylewski clouds in his peer-reviewed journal Monthly announcements from the Royal Astronomical Society. It said in a statement that a team of Hungarian astronomers and physicists may have confirmed the clouds where Kordylewski said they would be, in semi-stable points only 400,000 km from the earth.

For comparison, the average distance of the moon is 238,900 miles (385,000 km) from Earth.

View larger. | The concept of the artist of a Kordylewski cloud in the night sky at the time of the observations. The brightness has improved enormously; we would not really see this cloud. Image via G. Horváth / RAS.

If they exist, the Kordylewski clouds are at two special points in the earthmoon system. These points – known as Lagrange or Lagrange points – are known to be relatively stable, due to gravity. Objects, even dust, that float near these points tend not to travel to Earth or to the moon. They would have a tendency to sit, move forward and behind the moon in orbit around the earth. The RAS explained:

Two of these so-called Lagrange points, L4 and L5, form an equilateral triangle with the earth and the moon and move around the earth as the moon moves along its orbit.

L4 and L5 are not completely stable because they are disturbed by the gravity of the sun. Nonetheless, it is thought that these are locations where interplanetary dust can collect, at least temporarily. Kordylewski observed two nearby clusters of dust on L5 in 1961, with various reports since then, but their extreme fainting makes them difficult to detect and many scientists doubted their existence.

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In a document earlier in 2018, the Hungarian team, led by Gábor Horváth of the Eötvös Loránd University, modeled the Kordylewski clouds to assess how they form and how they can be detected. The researchers were interested in their appearance using polarizing filters, similar to those on some types of sunglasses. The RAS explained:

Scattered or reflected light is always more or less polarized, depending on the angle of scattering or reflection.

After they decided what to look for, the researchers went looking for the dust clouds. They established a linear polarizing filter system, attached to a camera lens and CCD detector, in the private observatory of Slíz-Balogh in Hungary (Badacsonytördemic).

Then the scientists took exposures of the alleged location of the Kordylewski cloud at the L5 point.

The images they have obtained reflect polarized light through dust, which extends well beyond the field of view of the camera lens. The RAS said:

The observed pattern corresponds to predictions from the same group of researchers in a previous paper and corresponds to the earliest observations of the Kordylewski clouds six decades ago.

The group of Horváth was able to exclude optical artefacts and other effects, which means that the presence of the dust cloud is confirmed.

Pattern of the polarization angle of the air around the L5 Lagrange point of the earthmoon system. Image taken on August 19, 2017. The position of the L5 point is indicated by a white dot. On this picture the central region of the Kordylewski dust cloud is visible (bright red pixels). The straight tilted lines are traces of satellites. Image via J. Slíz-Balogh / RAS.

Mosaic pattern of the polarization angle around the L5 point (white dot) of the earthmoon system. The five rectangular windows correspond to the visual fields of the imaging polarimetric telescope with which the polarization patterns of the Kordylewski dust cloud were measured. Image via J. Slíz-Balogh / RAS.

Judit Slíz-Balogh – who worked on this problem with the other scientists and is the lead author of one of the newspapers – noted:

The Kordylewski clouds are two of the most difficult objects to find, and although they are as close to the earth as the moon is largely overlooked by astronomers. It is intriguing to confirm that our planet has dusty pseudo-satellites in orbit around the moon next to our moon neighbor.

The RAS said:

Given their stability, the L4 and L5 points are seen as potential locations for space spaces in space and as transfer stations for missions exploring the wider solar system. There are also proposals to store pollutants on the two points.

Future research will look at L4 and L5, and the associated Kordylewski clouds, to understand how stable they really are and whether their substance poses a kind of threat to equipment and future astronauts.

Kazimierz Kordylewski presented the existence of the dust cloud satellites on Earth in 1961, and since then astronomers have talked about it. Are they now confirmed? This image from 1964 is via Wikimedia Commons.

In short, researchers say that they have confirmed the existence of the Kordylewski dust clouds, which rotate around the L4 and L5 points in the earth mesh system. In other words, the dust clouds rotate approximately in the orbit of the moon. They move in orbit behind and behind the moon.

Source # 1: Celestial mechanics and polarization optics of the Kordylewski dust cloud in the earth-moon lagoon point L5 – Part I. Three-dimensional celestial mechanical modeling of dust cloud formation

Source # 2: Celestial mechanics and polarization optics of the Kordylewski dust cloud in the Earth-Moon Lagrange point L5. Part II. Imaging polarimetric observation: new evidence for the existence of Kordylewski dust clouds


Deborah Byrd