Comets: the oldest inhabitants of the Solar system
J. L. Lagrange (1813) was also based on firmly established facts – the presence of comets that definitely move in elliptical orbits, including short-period. He explained the origin of comets gigantic volcanic explosions – emissions (eruption) with giant planets. It is, in principle, could explain the nature of the orbits of short-period comets. Subsequently, the views of La Grange shared and developed a number of scientists, among which the most important contribution of the Soviet astronomer S. K. Bo, who worked in this direction with the 20-ies to 80-ies of our century. He has eliminated the biggest internal difficulty is the concept of Lagrange – the necessity of the ejection of cometary masses (nuclei) with the “surface” of the giant planets with their powerful gravity fields, the overcoming of which requires an initial speed of 60 km/s and more. Giant planets also have thick (the length of many thousands of miles) and very dense atmosphere, in the middle of the twentieth century has been very problematic the very existence of a solid surface planets – giants beneath these atmospheres. Continue reading
In addition, comets can carry the names of the people who discovered them, e.g., comet Halley, comet Machholz, comet shoemaker–levy 9 comet or Mac Note.
Movement and spatial distribution
All comets are members of the Solar system. They, like the planets, are subject to the laws of gravity, but move very peculiar. All the planets revolve around the Sun in one direction (which is referred to as “direct” as opposed to “reverse”) on nearly circular orbits that lie roughly in one plane (the Ecliptic), while comets move in both forward and reverse directions on highly elongated (eccentric) orbits, inclined at different angles to the Ecliptic. It is the nature of motion immediately gives the comet.
Long-period comets (orbital period greater than 200 years) come from regions located thousands of times further than the most remote planets, and their orbits are tilted at all angles. Short-period comets (period less than 200 years) come from the region of the outer planets, moving in the forward direction for orbits lying close to the Ecliptic. Continue reading
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 provided 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. Continue reading