We are used to thinking that our planet has only one natural satellite - the Moon. However, recent theoretical calculations by American astronomers have shown that about a thousand different invisible objects are constantly in Earth's orbit, and in addition, a second satellite appears periodically near the Earth, which can be seen with the naked eye.
The computer model built by scientists is based on simulations of about ten million celestial bodies that regularly visit the Earth-Moon gravity system. Observations of this process led the researchers to come to the conclusion that at any given time there are many invisible bodies of natural cosmic origin in orbit around the planet, which revolve around the Earth along complex, spiral trajectories.
Since their own orbits are usually unstable, they stay near Earth for no more than a year. Then some of these bodies leave the "Earth - Moon" system and set off on a new "journey" around the Sun, and some of them are systematically captured by the gravity of our planet and its largest satellite, the Moon, and eventually falls to the Earth, burning in its atmosphere. Since the number of objects with a diameter of less than 30.5 centimeters is quite large, it can be concluded that many meteoroids falling to Earth are mini-satellites.
“We carefully tracked their movements, including the gravitational effects of the Sun and other planets, as well as the large asteroids of the solar system, and found that 18 thousand meteoroids were captured by the Earth and orbited around it for a short time,” comments one of the study's authors, Robert Jedike from the University of Hawaii (USA). “According to our estimates, at any arbitrary moment in time, one or two of these mini-moons are the size of a washing machine, and about a thousand are larger than a softball ball (30.5 centimeters in diameter).”
Why don't we notice these "additional" satellites? The fact is that the surface of the chondrites of which the meteoroids are composed is very dark, and therefore they are practically invisible against the background of the blackness of space. And their size is small. However, astronomers recorded the asteroid 2006 RH120, five meters in diameter, orbiting the Earth from July 2006 to July 2007, after which it left and went into free flight. Then it was not possible to identify him. Analysis of the reflected radiation has led to the assumption that the object is probably of anthropogenic origin.
By the way, according to the model, every half century our Moon attracts an object about ten meters in diameter, which for some time orbits around it. And the Earth, in turn, is capable of capturing objects with a diameter of about 100 meters once every 100 thousand years. These bodies should be visible from the surface of the planet with the naked eye, since, unlike meteoroids, they contain a large amount of metal, and the latter, as you know, is highly reflective. Our ancestors in the distant past could well have seen such a sight.
"A hundred thousand years is about the time when modern man left prints on the walls of caves, so that on this stretch someone could really see the mini-moon crossing the sky," says Robert Jedike.
And last year, the scientific journal Nature published an article in which it was suggested that at the dawn of the Earth's existence, that is, about 4.6 billion years ago, it had two permanent satellites and one of them eventually crashed into the other …
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And yet it cannot be said that the "extra" satellites are equivalent to the Moon. After all, they are much smaller than it in size and have only a temporary stay near the Earth.
However, there are also theories that the Moon can "run away" from the Earth and become an independent planet, thus repeating the fate of Mercury, which, as it is assumed, was once a satellite of Venus, but then "flew away" from it. Now the Moon is really moving away from the Earth, but very slowly - at a speed of about 38 millimeters per year.
For several billion years, the period of the Moon's revolution should increase by one and a half times, but this does not mean that the satellite will leave the Earth. In addition, scientists have calculated, over time, the moon will again approach us. As a result, in five billion years, the radius of the lunar orbit will reach its maximum value - 463 thousand kilometers, and the duration of the earth's day will increase to 870 hours, the researchers promise.
But after such a huge period of time, perhaps humanity will already cease to exist or settle in other stellar systems. So we and our descendants will have to live under the moon for many generations.