The existence of two elusive clouds of dust that extend semi-stably only 400,000 kilometers from Earth could be confirmed by a team of Hungarian astronomers and physicists.
The clouds, reported for the first time and named by the Polish astronomeror Kazimierz Kordylewski in 1961, they are exceptionally weak, so their existence is controversial. The new work appears in the monthly magazine Notices of the Royal Astronomical Society.
The Earth-Moon system has five points of stability wheree the gravitational forces maintain the relative position of the objects located there. Two of these so-called Lagrange points, L4 and L5, form a triangle of equal sides 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 gravitational force of the Sun. However, they are thought to be places where interplanetary dust could accumulate, at least temporarily. Kordylewski observed two groups of dust nearby in L5 in 1961, with several reports since then, but their extreme weakness makes them difficult to detect and many scientists doubted their existence.
In a study earlier this year, the Hungarian team, led by Gábor Horváth of the Eötvös Loránd University, modeled the Kordylewski clouds to evaluate how they are formed and how they could be detected. Researchers were interested in their appearance using polarizing filters, which transmit light with a particular direction of oscillation, similar to those found in some types of sunglasses. The scattered or reflected light is always more or less polarized, depending on the angle of scattering or reflection.
Then they set out to look for the clouds of dust. With a linear polarization filter system connected to the lens of a camera and the CCD detector in the private observatory of Slíz-Balogh in Hungary (Badacsonytördemic), the scientists exposed the supposed location of the Kordylewski cloud at point L5.
The images that they obtained show Polarized light reflected in the dust, extending well out of the field of view of the camera lens. The observed pattern coincides with the predictions made by the same group of researchers in a previous article and is consistent with the earliest observations of Kordylewski clouds six decades ago. Horváth's group was able to discard optical artifacts and other effects, which means that the presence of the dust cloud is confirmed.
Judit Slíz-Balogh comments on her discovery in a statement: "The Kordylewski clouds are two of the most difficult objects to find, and although they are as close to the Earth as the Moon they are ignored by researchers in astronomy. It is interesting to confirm that our planet has dusty Pseudo-satellites in orbit next to our lunar neighbor. "
Given their stability, points L4 and L5 are seen as potential sites for space probes in orbit, and as transfer stations for missions that explore the broader Solar System. There are also proposals to store contaminants in the two points. Future research will analyze L4 and L5, and the associated Kordylewski clouds, to understand how stable they really are, and if their dust poses any threat to future spacecraft and astronauts. "