Comets from the far reaches
Astronomers have determined that comets from the far reaches of our Solar system do not threaten the Earth. The discovery was made after computer modeling of the behavior of these objects. Article researchers appeared in the journal Science . and its summary is contained in the press release of the University of Washington, where the authors of the article.
In their study, the astronomers modeled the penetration into the inner part of the Solar system comets from the Oort cloud – a region whose borders, according to various estimates, are spaced from 2 to 50 thousand astronomical units. The temporal interval was modeled astronomers, was about 1.2 billion years.
Previously, scientists were convinced that the majority of comets with a long period (from 200 to millions of years) period of treatment, currently there are about 3200, with the outer part of the Oort cloud. It was believed that comets from the inner part of the cloud protects the Solar system gravitational field of Saturn and Jupiter, which do not allow these bodies to “annoy” the Earth and other small planets.
New results show that it is not. A new computer model has allowed to detect the crack in gravity to protect the inner part of the Solar system, which is able to penetrate the comet from the inner part of the Oort cloud. Using this data, scientists were able to estimate colecistectomy in this part of the Oort cloud.
Using the resulting scores, the researchers calculated the number of comets with a long period of treatment, which could fall to Earth over the past 500 million years. As a result they managed to establish that during this time our planet is supposed to deal only with two or three comets. Given that about 40 million three years ago, a comet collided with the Earth in between about a million years apart, the researchers concluded that the meeting of the Earth with a comet from the Oort cloud is a rather unlikely event.
New results about the relative safety of comets do not apply, however, to the comet with a short period of treatment (for example, Halley’s comet with a period of about 75 years). It is believed that these bodies originate from the so-called Kuiper belt region, located beyond the orbit of Neptune (about 30 astronomical units).