Scientists first discovered particles of cosmic dust on rooftops in Paris and Oslo. This is reported in an article published in the journal Geology.
Since the 40s of the last century, researchers have known that small particles of cosmic dust constantly enter the Earth's atmosphere. Antarctica is usually considered the most popular place to find them. This is due to the fact that the air there is less polluted than in other parts of the planet, and the dark dusty substance is clearly visible on clean white snow. However, scientists are not abandoning their attempts to find particles that arrived from space, and in cities, which is especially difficult to do, since a lot of earthly dust accumulates there (transport and industry serve as its source). However, researchers from the UK, Norway and Belgium reported that they found space dust right on the rooftops.
The authors of the work have collected 300 kilograms of dust, which has accumulated in the gutters of houses located in Paris and Oslo. Using magnets, they selected particles containing magnetic minerals, then rinsed them with water and sorted them according to size. Then the geologists examined the samples obtained under a microscope and selected only those particles that had features characteristic of cosmic dust: spherical or sub-spherical shape, black or gray color and luster, as well as a special surface structure.
As a result, the researchers managed to "catch" 500 silicate particles of cosmic dust. All of them had a sub-spherical shape and reached 0.3 millimeters in diameter. This turned out to be unexpected for geologists, since they usually found much smaller samples, about 0.01 millimeters in size. In addition, as reported by New Scientist, the urban particles differed from the Antarctic ones in that they contained fewer branching crystals (dendrites).
Scientists believe that all the particles have fallen to Earth over the past six years, which means they can be considered the most "fresh" micrometeorites to date. Their unusually large size was explained by geologists by the fact that the orbits of the planets, including Earth and Mars, evolve, that is, they slowly change their parameters. Because of this, gravitational perturbations arise, which can affect the trajectory of dust particles and the speed with which they enter the atmosphere of our planet, which in turn affects their size.
Scientists from NASA recently analyzed particles of cosmic silicate dust that they found in meteorites that fell on our planet. It turned out that about one in 5 thousand particles was born by another star that existed before the formation of the solar system. Dust surveys have also been conducted by Cassini, which recently embarked on a series of dives near Saturn's F-ring. The particles collected by the spacecraft had approximately the same chemical composition and probably appeared due to an unknown repeating process taking place in the interstellar medium.
Christina Ulasovich