One or two ghostly dust satellites can orbit the Earth, according to a new study based on a 60-year-old idea.
Massive objects attract by gravity. However, if you have several large objects with just the right mass, their mutual gravitational field can cause anomalies – such as gravity points that can keep things stable. Scientists have found objects orbiting in these "Lagrange points" and produced by the combined gravitational force of the Sun and Mars, the Sun and Neptune, and the Sun and Jupiter. Researchers are now reporting dust clouds, the so-called Kordylewski dust clouds, in the Lagrange points created by Earth and Moon.
The Swiss mathematician Leonhard Euler predicted the first three Lagrange points in these systems from 1
The Earth and the Moon are in the right proportions, so that a certain amount of mass could orbit the system stably at L4 and L5, the two Lagrange points that Lagrange himself discovered. The Polish scientist Kazimierz Kordylewski observed signs of dust clouds in the vicinity of L5 in 1961. Since then, these clouds of dust have hardly been explored. In the past two months, however, research teams have investigated whether these clouds could exist despite the additional gravitational force of the Sun or its solar winds.
The Eötvös Loránd University Team First, a mathematical simulation based on the equations of a system containing the Sun, Earth, Moon and a fourth dust cloud was created. They found that a swirling, ever-changing dust cloud was absolutely possible at L5, according to the first of two articles in the Monthly Notices of the Royal Astronomical Society. This confirmed another analysis by a team of Russian scientists published a month earlier.
But would they actually see a Kordylewski cloud? The team started with the private observatory of study author Judit Slíz-Balogh in Badacsonytördemic, Hungary, with special lenses that could measure the polarization of the light – essentially the orientation of the corresponding electric field moving through space. They hoped they could see the signature of the Kordylewski dust cloud in terms of the polarization of L5's light.
They found it, but not without effort. "After several months of persistence (because it is difficult in Hungary to find moonless and cloudless good nights), we have been able to catch the [Kordylewski dust cloud] on two consecutive nights around the L5 Lagrange point," she wrote in the second in the Monthly Bulletin of the Royal Astronomical Society.
Although the team has the modeling and observation to back it up, it's still worth treating the conclusion with a grain of salt. According to the report, their observations may be a temporary phenomenon, and the dust they saw could easily be blown away from other planets or through the solar wind by shaking gravity. Many other telescopes as well as a Japanese probe have found no evidence of the dust – although other observations may be different, although the researchers have been very careful to exclude other possible sources of this polarized light. The researchers argue that their polarization observation method provided a better way to detect the dust cloud.
So is the cloud really there? The latest evidence points to yes – and if it's really there, it means that we have at least one, if not two, goblet probes with another possible dust cloud at L4. Spoooooky!