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The Oort cloud is thought to have developed after the formation of planets from the primordial protoplanetary disc approximately 4.6 billion years ago. [4] The most widely accepted hypothesis is that the Oort cloud's objects initially coalesced much closer to the Sun as part of the same process that formed the planets and minor planets.
The concept of such a cloud was proposed in 1950 by the Dutch astronomer Jan Oort, in whose honor the idea was named. Oort proposed that the bodies in this cloud replenish and keep constant the number of long-period comets entering the inner Solar System—where they are eventually consumed and destroyed during close approaches to the Sun.
The existence of planets beyond Neptune, ranging from less than an Earth mass up to a brown dwarf has been often postulated [37] [38] for different theoretical reasons to explain several observed or speculated features of the Kuiper belt and the Oort cloud.
Artist's rendering of the Kuiper belt and Oort cloud. Freeman Dyson proposed that trans-Neptunian objects, rather than planets, are the major potential habitat of life in space. [citation needed] Several hundred billion to trillion comet-like ice-rich bodies exist outside the orbit of Neptune, in the Kuiper belt and Inner and Outer Oort cloud.
About 1.3 million years ago the object may have passed within a distance of 0.16 parsecs (0.52 light-years) to the nearby star TYC 4742-1027-1, but its velocity is too high to have originated from that star system, and it probably just passed through the system's Oort cloud at a relative speed of about 15 km/s (34,000 mph; 54,000 km/h).
Artist's view of the theoretical Oort cloud, Hills cloud, and Kuiper belt (inset) In astronomy, the Hills cloud (also called the inner Oort cloud [1] and inner cloud [2]) is a theoretical vast circumstellar disc, interior to the Oort cloud, whose outer border would be located at around 20,000 to 30,000 astronomical units (AU) from the Sun, and whose inner border, less well defined, is ...
Simulations indicate that it has most likely come from the Oort cloud, with a roughly equal probability of being an extinct comet and a rocky body that was originally scattered into the Oort cloud. The discovery of 1996 PW prompted theoretical research that suggests that roughly 1 to 2 percent of the Oort cloud objects are rocky. [2] [10]
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 ...