For more than half a century, scientists have debated over the existence of two puzzling celestial objects known as the Kordylewski dust clouds.
These dust clouds were first observed by Polish astronomer Kazimierz Kordylewski in 1961 and are thought to orbit our planet around the L4 and L5 Lagrange points — two of the five gravitationally stable locations found in the Earth-moon system.
Although subsequent sightings of the Kordylewski dust clouds have occasionally been reported, their presence in our planet's orbit has remained controversial. This is because the dust clouds are "exceptionally faint," notes Science Daily, which makes detecting them extremely challenging.
Nevertheless, it seems that the elusive clouds have been successfully spotted by a team of Hungarian astronomers and physicists, who finally confirmed their existence, reports the media outlet, citing the Royal Astronomical Society.
According to the team, the Kordylewski dust clouds were observed some 400,000 kilometers from Earth (or nearly 250,000 miles), around the L5 Lagrange Point.
"The Kordylewski clouds are two of the toughest objects to find, and though they are as close to [the] Earth as the moon, [they] are largely overlooked by researchers in astronomy. It is intriguing to confirm that our planet has dusty pseudo-satellites in orbit alongside our lunar neighbor," said Judit Slíz-Balogh, one of the researchers who made the discovery.How to you go about finding something that is virtually untraceable? In this particular case, the scientists started by developing a computer model of the Kordylewski dust clouds in order to understand how they form and what is the best way to detect them.
The results of their simulation were published earlier this year in the Monthly Notices of the Royal Astronomical Society and highlighted that the mysterious dust clouds could be spotted with the help of polarizing filters — optical filters that transmit light with a particular direction of oscillation. These filters allow only light waves of a specific polarization to pass through, while blocking everything else.
The next step was to apply the technique when observing the sky and actively look for the Kordylewski dust clouds around L4 and L5. Unlike the other three Langrangian points, which form a line that goes through Earth and its natural satellite, L4 and L5 form an equal-sided triangle with the our planet and the moon and constantly move around the Earth as the moon moves along its orbit. This makes them less gravitationally stable, which has prompted scientists to doubt whether dust can accumulate in these locations.
"Many astronomers assume that these dust clouds do not exist, because the gravitational perturbation of the sun, solar wind, and other planets may disrupt the stabilizing effect of the L4 and L5 Lagrange points of the Earth and moon," the scientists point out in a second paper, also published in the Monthly Notices of the Royal Astronomical Society.Using a highly sensitive photon detector and a linearly polarizing filter system attached to a camera lens, the team imaged the areas and picked up a type of polarized light that could only be reflected by dust accumulated near the L5 Lagrange Point.
The pattern of the detection matched both their predictions from the previous study and the observations made by Kordylewski all those decades ago.
"Excluding artifacts induced by the telescope, cirrus clouds, or condensation trails of airplanes, the only explanation remains the polarized scattering of sunlight on the particles collected around the L5 point," concludes the team.