This invisible and distant region of the solar system is home to hundreds of billions of icy bodies, bordering on the attraction of the sun.
Orbiting very fragile, almost motionless, the most distant comets from the Sun can be affected by any force of gravity, the stars closest to the solar system. The solar system is subjected during its journey through the galaxy, gravitational influences that can alter this balance and cause the comets to fall at the heart of the system and therefore the planets. Astronomers estimate that stellar gravitational disturbances can be very high since some stars pass “close” to the sun.
On average, a star passes within 10,000 astronomical units of the Sun every 36 million years and less than 3,000 astronomical units every 400 million years. Edgar Everhart, an American astronomer, found that if a comet enters the solar system with an orbital inclination of more than 20°, it has a chance of even being ejected from the solar attraction. The Oort cloud is a remnant of the primitive nebula that collapsed on itself, there are 5 million years.
After their formation by accretion, all the small trans-Neptunian objects have been influenced by the giant gaseous planets, pushing them to the periphery of the system.
These Oort cloud objects are in a primitive state since their creation, they are the materials that make up the solar system at its origin.
It is possible that life came from comets is at the time of incessant bombardment of meteorites, since they are made of oxygen, carbon, nitrogen, magnesium, silicon, iron … what with a little water, organic soup that leads to the first living organisms.
Comets were unable to form the Oort cloud, where they reside today, because at these distances, the material is too sparse to condense. The only possible place of creation is the planetary system. According to Jan Oort, comets formed in the asteroid belt (between the orbits of Mars and Jupiter) and expelled by the giant planets during the formation of the solar system.
However, comets are icy bodies, like a big dirty snowball, and the asteroid belt was too hot for the ice to condense.
In 1951, a year after the publication of Oort’s article, Gerard Kuiper suggested that comets condense farther from the Sun, between the giant planets in the belt that bears his name, the Kuiper Belt, will be located in the plane the ecliptic beyond the giant planets.
Because the orbits of long-period comets are so extremely long, scientists suspect that the Oort cloud is the source of most of those comets. For example, Comet C / 2013 A1 Siding Spring, which made a very close pass by Mars in 2014, will not return to the inner solar system for about 740,000 years.
“The frozen bodies, similar to the comets of the Oort Cloud, are not capable of supporting life as we know it.”
The distance from the Sun to the Oort Cloud is so enormous that it is useful to describe it not in the most common units of miles or kilometers, but in astronomical units. One astronomical unit (or AU) is the distance between the Earth and the elliptical orbit of the Sun. The inner edge of the Oort cloud, however, is believed to be between 2,000 and 5,000 AU from the Sun. The outer edge could be 10,000 or even 100,000 AU from the Sun, that is, a quarter halfway between the Sun and the nearest neighboring star.
Oort cloud formation.
The main idea for the formation of the Oort Cloud says that these icy objects were not always that far from the Sun. After the planets formed 4.6 billion years ago, the region in which they formed still contained many leftover chunks called planetesimaales. The planetesimas were formed from the same material as the planets. The gravity of the planets (mainly Jupiter) then scattered the planetesimaals in all directions.
Some planetesimals were ejected from the solar system entirely, while others were thrown into eccentric orbits where they were still held back by the Sun’s gravity, but were far enough away that galactic influences were thrown at them as well. Probably the strongest influence was the tidal force of our galaxy itself.
In short, the gravity of the planets pushed many icy planets away from the Sun, and the gravity of the galaxy likely caused them to settle in the borderlands of the solar system, where the planets could no longer disturb them. And they became what we now call the Oort Cloud. Again, that’s the main idea, but the Oort cloud could also capture objects that don’t form in the solar system.
Orbit and Rotation.
Unlike planets, the main asteroid belt, and many objects in the Kuiper Belt, objects in the Oort Cloud do not necessarily travel in the same direction in a shared orbital plane around the Sun. Instead, they can travel underneath, above and at various inclinations, around the Sun as a thick bubble of distant, icy debris. Hence, they are called the Oort Cloud rather than the Oort Belt.
Dutch astronomer Jan Oort proposed the existence of the cloud to explain (among other things) where long-term comets come from, and why they appear to come from all directions rather than along the orbital plane shared by the planets, asteroids and the Kuiper Belt.