In 2001, a group of American astronomers was on duty, as usual at night, at the main telescope on the top of Mauna Kea in Hawaii and in between times argued about: "How many more" moons "are left not discovered in the solar system?"
Astronomer Jewitt immediately made a bet of $ 100 in favor of the fact that no more than 10 new "moons" remained in the solar system. In support of his "norm", Jewitt referred to statistics from the 20th century, when astronomers found only a few such space objects. Astronomer Sheppard, head of the night vigil, was more optimistic, increasing the "rate" to 20 new "moons" in the hope of increasing the sensitivity of new astronomical instruments.
Since that time, Sheppard's astronomers have discovered an additional 62 "moons"! The other observation teams received an additional 24 "moons". Strictly speaking, these objects are not "moons", but satellites of giant planets, and only the Earth has a real Moon. But astronomers habitually call them "moons."
Nobody imagined that the family of the solar system contains so many "moons". Astronomers classify most of them as irregular, characterized by huge elongated elliptical orbits with an inclination of their planes at an angle to the equatorial plane of the "mother" planets. In addition, many irregular "moons" have retrograde orbits, that is, they revolve around the "mother" planet in the opposite direction to it.
The so-called regular "moons" include the Earth's Moon and four large Galilean satellites of Jupiter, which differ in their relatively close location, circular orbit and rotation in the equatorial plane of the "mother" planet.
A look at the North Polen
In this case, we will find that our Moon revolves around the Earth counterclockwise, that is, in the same direction in which our planet revolves around its axis when moving around the Sun. Other planets also rotate counterclockwise, which indicates the same spinning of the gas and dust disk that gave birth to the planets 4.5 billion years ago. Regular "moons, too, move in a similar way, that is, they, too, according to astronomers, were formed in a gas and dust disk revolving around the corresponding planet. Thus, the different - behavior - of irregular "moons" testifies to their other origin.
Irregular "moons"
So, most of the planetary "moons" were formed in gas and dust disks revolving around the corresponding planets, reproducing in miniature the formation of the solar system itself. These "moons" rotate in the plane of the equators of the respective planets and in the same direction. "Moons" that do not fulfill these conditions are considered irregular.
The recent stream of astronomical discoveries, due to the creation of digital observational instruments, has shown a huge quantitative predominance of irregular "moons" over regular ones. Their intricate orbits indicate that they did not form at the point where they were seen, but in orbit around the Sun. Perhaps these celestial bodies are asteroids or comets captured by the respective planets. But their exact origin and the mechanism of "capture" by the planets are unknown. Some astronomers do not exclude their arrival from the Kuiper belt (beyond Neptune). Their "captures" can be accompanied by collisions with each other in young zones, where the corresponding objects have not yet scattered.
By the way, the strange properties of the orbits of irregular "moons" are explained by their initial whirling around the Sun, followed by "captivity" of any of the approaching planets. Astronomers offer three options for "captivity", but they all begin with the formation of the so-called
planetesimals (bodies similar in size to asteroids).
The remaining production wastes are used to form rocky shells of giant planets.
Irregular -moons "have not yet received an explanation from the standpoint of the standard model of the universe, but the theoretical aspects of this problem are already being developed. These developments date back to times long past, when gravitational influences are just now. the nascent planets scattered or, conversely, concentrated in one place the future "moons".
A study of the features of this epoch will shed additional light on the problem of the origin of the solar system.
Research historyPromotional video:
Although the first known irregular "moon", Triton, a satellite of Neptune, was discovered in 1846, most of these "moons" have escaped detection to this day. In addition, they turned out to be scattered over vast spaces. For example, the outermost regular "moon" of Jupiter Callisto orbits at a distance of 1.9 million kilometers from the planet, while the known irregular moons of Jupiter are located at a distance of 30 million kilometers! This distance is comparable to the radius of the gravitational sphere of Jupiter, beyond which the moons can go irrevocably! If this sphere could be seen, it would occupy 10 arc degrees of the sky, which would be 20 times the angular dimensions of the full moon. Effective scanning of such a large area of the sky requires the development of the latest digital observational instruments.
The four giant planets in the solar system are Jupiter. Saturn, Uranus and Neptune - have, as it turned out, similar systems of irregular moons. Extrapolating from the total number of celestial bodies of this type discovered so far, we get one hundred irregular -moons with a diameter of more than a kilometer! And there are even more of them with a smaller diameter!
The orbits of these celestial bodies, as everyone knows, are an incredible interweaving of routes!
Collisions
So, Jupiter now has 8 regular moons and 55 irregular moons, Uranus has 18 regular and 9 irregular moons, Neptune has 6 regular and 7 irregular moons, and Saturn has 21 regular and 2 irregular moons. Colorado astronomer David Nesvorny and his co-workers simulated collisions between the moons and found that, fortunately, such cosmic cataclysms are extremely rare today.
One of the few irregular moons around Saturn, Phoebus, has been the most thoroughly studied. Moreover, in June 2004, she was visited by the NASA spacecraft Kas-blue. took many very high-resolution images of the moon and recorded the spectrum of reflected sunlight, indicating the presence of water and carbon dioxide in the form of ice there, as well as an abundance of craters!
Two irregular moons near Neptune - Nereid and Triton - were photographed by the Voyager 2 spacecraft, which found an icy surface on them. The presence of ice means that these celestial bodies formed relatively far from the Sun. And Jupiter's irregular moons turned out to be pitch black, which means they were free of ice.
Therefore, they formed relatively close to the Sun and the ice could melt.
German GORDEEV