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The Oort cloud (/ ɔːr t, ʊər t /), [1] sometimes called the Öpik–Oort cloud, [2] is theorized to be a vast cloud of icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years). [3] [note 1] [4] The concept of such a cloud was proposed in 1950 by the Dutch astronomer Jan Oort, in whose ...
The Oort cloud (/ ɔːr t, ʊər t /), sometimes called the Öpik–Oort cloud, is theorized to be a vast cloud of icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years). The concept of such a cloud was proposed in 1950 by the Dutch astronomer Jan Oort, in whose honor the
The Oort cloud (artist's rendering pictured) is a hypothesized spherical cloud of comets that may lie nearly a light-year from the Sun. It is thought to comprise two separate regions: a spherical outer Oort cloud and a disc-shaped inner Oort cloud, or Hills cloud; the outer extent of the cloud defines the boundary of the Solar System.
The hypothesized Oort cloud is thought to be a spherical cloud of icy bodies extending from outside the Kuiper belt and the scattered disk to halfway to the nearest star. During planet formation interactions of protoplanetary disk objects with the already developed Jupiter and Neptune resulted in the scattered disc and the Oort cloud. [86]
Following the discovery of Leleākūhonua, Sheppard et al. concluded that it implies a population of about 2 million inner Oort cloud objects larger than 40 km (25 mi), with a combined total mass of 1 × 10 22 kg, about the mass of Pluto (a fraction the mass of Earth's moon but several times the mass of the asteroid belt). [5]
Numerous such comets have been observed when close to the Sun. The closer an object is to the Sun the faster it needs to move to maintain the orbit. Objects move slowest when furthest from the Sun (aphelion) and fastest when closest to the Sun (perihelion) and this is why Oort cloud comets spend most of their time in the Oort cloud.
Figure 1: Geometry of the Oort constants derivation, with a field star close to the Sun in the midplane of the Galaxy. Consider a star in the midplane of the Galactic disk with Galactic longitude at a distance from the Sun. Assume that both the star and the Sun have circular orbits around the center of the Galaxy at radii of and from the Galactic Center and rotational velocities of and ...
2012 VP 113 (possibly inner Oort cloud) Sedna, a dwarf planet (possibly inner Oort cloud) Oort cloud (hypothetical) Hills cloud/inner Oort cloud; Outer Oort cloud; The Solar System also contains: Comets. List of periodic comets; List of near-parabolic comets; Small objects, including: Meteoroids; Interplanetary dust. Helium focusing cone ...