Oortcloud

The Oort Cloud, also known as the Öpik-Oort Cloud (Hebrew: ענן עופיק-אורט, Anan Ofeek-Oort; Dutch: Oortwolk; German: Oortsche Wolke), is a theoretical cloud of predominantly icy planetesimals proposed by Dutch astronomer Jan Oort to exist in the outermost region of the Solar System, at a distance roughly 50,000 to 200,000 AU (0.8 to 3.2 light years) from the Sun. This cloud is believed to be the source of most long-period comets that enter the inner Solar System. The Oort Cloud is thought to be a remnant from the early Solar System's formation, consisting of icy bodies that were ejected from the inner Solar System by the gravitational interactions with the giant planets. The existence of the Oort Cloud is widely accepted, although it has never been directly observed. Its presence is inferred from the behavior of long-period comets and the distribution of their orbits. The Oort Cloud is considered to be a spherical shell surrounding the Solar System, with a total mass estimated to be around 3 to 20 times that of the Earth.