A photo from open sources
Over the past five years, astronomers have counted in our solar system several tens of satellites (at the time of preparation of this articles were 86) moving around their planets in the direction opposite to their rotation! They are called irregular (in unlike regular, going forward relation to their planets). It seems like irregular satellites arose in the old days when gravitational influences newborn planets were torn down by smaller bodies with their original orbits and transferred them to reverse orbits. The scientist has become it is clear that the study of these processes can shed light on the very early stages of the formation of the solar system. “Travel” giant planets. Oddly enough, the first irregular satellite, named Triton, was discovered back in 1846 at the penultimate of the famous planets of the solar system – Neptune. To this satellite can say lucky since most irregular satellites due to their small size and low luminosity very hard. In addition, unlike regular satellites, they scattered over a large space. For example, the most remote Jupiter’s regular satellite is at a distance of two million kilometers from your planet, and famous irregular satellites Jupiter rotates 30 million kilometers away from it! Recall that the giant planets in our solar system are Jupiter, Saturn, Uranus and Neptune. Until recently, for Jupiter “counted” 8 regular satellites and 55 irregular, for Saturn – 21 regular and 26 irregular, beyond Uranus – 18 regular and 9 irregular, for Neptune – 6 regular and 7 irregular and beyond Pluto – 1 regular satellite. Now picture has changed dramatically. It turned out that four giant planets have many irregular satellites. According to the results extrapolation of available astronomical data from each of giant planets should be around with t a (!) irregular satellites diameter over a kilometer! In the system of satellites of Jupiter, these dimensions range from 180 kilometers (near the Himalayas) to two kilometers from the smallest fellow travelers. These satellites are moving along the most complex in the solar system – loop-shaped orbits. Since the irregular “fellow travelers” are on a very large away from their planets they are almost equally affected the gravitational forces of its planet and the sun. The result is fast precession of the satellite’s orbit (turning its major axis ellipse). The rhythms of space. If the specified precession corresponds to the frequency of revolution of the planet around the sun, satellite falls into resonance. In this situation, gradually accumulate consequences of solar gravity, deforming the satellite’s orbit: its the ellipse extends to such an extent that the satellite either collides with his planet, or bursts into gravitational “hugs” The sun! Analysis of various effects on satellite motion allowed detect in the Jupiter system up to 17 fragments that crashed during collision of a larger “companion”. One of the few well the irregular moons studied is the Saturn satellite of Phoebe. is he was investigated by the Cassini space interplanetary probe in June 2004 year. With its help, it was possible to get clear images numerous craters and reflected sunlight spectra, indicating the presence on Phoebe of ice from water and dioxide carbon. The satellites of the planet Neptune Triton and Nereid, investigated probe “Voyager 2”. also turned out to be covered in ice. Consequently, they formed far from the sun. Remnants of the “building material. “There is reason to believe that irregular satellites are remnants of “building material” from planet formation. Like asteroids and comet nuclei, they first revolved around the sun, and then were captured by planets. The famous comet Shoemaker-Levy 9, for example, was captured complicated gravitational interactions and was on temporary orbit around Jupiter, after which in 1994 there was torn by the gravitational forces of the planet and fell on it. If this did not happen, then after hundreds of years the comet would again be on heliocentric orbit! Astronomers know several cases returning to the near-solar space of objects after temporary “capture” them by Jupiter. Capture options. in the 70s last century, theorists have proposed three options for the capture scenario satellites. In the first case, the “candidate” for satellites, if it is small in size, it will burn in the atmosphere of the planet, past which it flies If the “candidate” is large in size, it will pass through it and will continue its path in orbit around the sun. Only with medium the size of the “lost” celestial body will be captured the planet. The second capture mechanism is triggered at the growth stage the planet. Asteroids and other “candidates” in satellites fall into peculiar gravitational trap due to sharply increased mass the planet. As in the previous scenario, this option does not explain the presence of satellites in Neptune and Uranus, which did not survive a sharp increase in mass. In 1971, the third option was proposed. the problem we are interested in, the basis of which is the process collisions of two bodies in space. But later it turned out that the capture can happen without a collision. In May 2006, astronomers proposed another option for triple capture: with it, the satellite system – the planet “is torn by gravitational forces, one of the components ejected from the system, and the second – goes into its orbit. Where did the “fellow travelers” come from? According to the latest astronomical discoveries, all four giant planets in The solar system is surrounded by irregular satellites. Looking for them origin scientists focused on studying the triple scenario capture “candidates.” That triple capture can explain almost the same number of irregular satellites of giant planets. However, the question remains: where did these satellites come from? Scientists offer two answers to this question. According to the first variant, the “candidates” could be asteroids and nuclei of comets, caught in the same region of the solar system as the ones that captured them the planet. The second answer is based on the assumption that approximately 700 million years after completion of formation planets The solar system was abundantly littered with planetesimals (“germ” of future celestial bodies). At some point during “taxiing” of large planets to their modern orbits and in the result of the powerful gravitational interactions of Saturn and Jupiter a myriad of asteroids and comets were scattered in space space. Some of these wandering bodies could be captured large planets. The bulk of the scattered “candidates” in satellites focused beyond the orbit of Neptune in the so-called belt Kuiper. Prospects. Now the study is actively ongoing irregular satellite systems. Already managed to prove that captures “candidates” for these satellites occurred in the early stages of evolution Solar system since in later times the conditions for this was already gone. In addition, the similarity of irregular systems satellites of giant planets indicates the appearance of these “fellow travelers” as a result of triple capture – the only a mechanism suitable for both Neptune and Jupiter, So way, irregular satellites centered around giant planets keep the memory of the events that took place many millions of years ago. G. Gordeev
Neptune Saturn Sun Solar System Jupiter
