Oort Cloud Facts

Oort Cloud Facts
The Oort Cloud is a giant shell of icy bodies that is thought to encircle the Solar System. It still hasn't been discovered, as it is still just a theory, although Scientists have studied several comets believed to have come from the distant region. There is thought to be billions, even trillions of bodies in it. The shell was first proposed in 1950 by Jan Oort. He suggested that some of the comets entering the Solar System came from a cloud of ice bodies that may lie as far as 100,000 times Earth's distance from the sun, which is a distance of up to 9.3 trillion miles (15 trillion kilometers). The extreme distance makes it challenging even today for scientists to identify objects within in it.
Interesting Oort Cloud Facts:
There are two types of comets that travel through the Solar System. There are those with short periods, around a few hundred years, that stem from the Kuiper Belt which is a pancake of icy particles near the orbit of Pluto.
There are longer period comets with orbits of thousands of years that come from a distant Oort Cloud. Comets from the Oort Cloud can travel as far as three light years from the Sun. The farther they travel, the weaker the Sun's gravitational hold is.
Objects in the Oort Cloud are also called Trans-Neptunian objects. The name also applies to objects in the Kuiper Belt.
Discovered in 2003, the planetoid Sedna is thought to be a member of the inner Oort Cloud.
Some astronomers believe that the Sun may have captured Oort Cloud cometary material from the outer disks of other stars that were forming in the same nebula as our star.
The Oort Cloud inner limits begin at about 2,000 AU from the Sun. It is so distant from the Sun, but can be disrupted by the nearby passage of a star, nebula or by actions in the disk of the Milky Way. Those actions knock cometary nuclei out of their orbits and send them on a fast rush toward the Sun. The path of the comets is constantly shifting with many factors that influence it.
It is spherically shaped and consists of an outer cloud and a torus inner cloud. The cloud stretches out almost a quarter of the way to the nearest star, Proxima Centauri.
In 1996, the comet Hyakutake passed Earth when it was completing a journey of about 17,000 years from the Oort Cloud. It came within 9 million miles (15 million kilometers) of Earth.
Halley's Comet is believed to have originated from the Oort Cloud, but is now a Kuiper Belt object.
The Oort Cloud comet Siding Spring was discovered on January 3, 2013. It made a very close pass by Mars in 2014 and will not return to the inner Solar System for about 740,000 years.
Space probes have yet to reach the Oort Cloud. The inner planetary space probe Voyager 1 is currently leaving the Solar System and will reach the Oort Cloud in about 300 years and would take an estimated 30,000 years to pass through it.

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