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article imageOort Cloud — Ice and dust encircles Sun at 100,000 AUs above

By Karen Hardison     Apr 22, 2015 in Science
Jan Oort's Comet Cloud is getting attention again because of its role in a new model of Galactic disc dark matter that connects the interaction between dark matter and Oort comets with Earth's mass extinctions. But what is the Oort Comet Cloud?
Hypothesized by Dutch astronomer Jan Oort in 1950 to explain long-period comets having large, eccentric orbits taking thousands of years to circle the Sun, the as yet theorized Oort Cloud has two interesting properties. First, it encircles the Solar system with an icy cloud comprised of ice-and-dust comets typically measuring about 2 miles (or a few kilometers) across. Second, this hypothetical enshrouding cloud has depth and is spherically spread between 5000 and 100,000 astronomical units (AUs) from the Sun, too far for telescope or satellite observation.
The Oort cloud circles in an elliptical pattern, coming much closer to the Sun at one side than at the other side of the swirling cloud. In other words, the movement of the spherical (not planar like the Kuiper belt) Oort cloud is skewed and asymmetrical. Observation of long-period comets, which take thousands of years to orbit the Sun, provided the basis for the proposed Oort Cloud.
Oort Cloud and the Galactic Disc
Our Solar system travels in vertical oscillations, an up-and-down wave formation, in an approximately 30 million year (Myr) cyclical pattern as it journeys on its 250 Myr orbit around the Galactic center of our Milky Way Galaxy. When the Solar system approaches the Galactic mid-plane, strong Galactic gravitational tidal forces disrupt the order of the Solar system. This disruption to stable order is called perturbation. You might envision iron shavings being brought in an approach toward magnetic force. The approach toward the magnetic force perturbs the order of the iron causing disarrangement. You might also envision two magnets of like polarity approaching each other. The like magnetic forces cause repelling energy that can perturb the positions of the magnets (if the charges are unlike, they attract rather than repel).
Similar perturbation as seen in magnetism occurs when the Solar system approaches the strong Galactic gravitational tidal forces at the Galactic mid-plane. Since the Oort Cloud is the structure at the outermost limits of the Solar system — enshrouding it as it does — where the Solar system's gravitational pull is the weakest, the comets in the Oort Cloud will be the first structures perturbed in this approximately 30 Myr cycle and will be the structures perturbed to greatest degree.
As a consequence of the perturbation, comets may fly loose and exit the gravitational force of the Solar system entirely or they may fly inward toward the interior, toward planets and the Sun. This gravitational tidal force perturbation can send Oort comets on new erratic, inward orbits that result in impact contact with planets, including Earth. Geological and biological record shows that such Oort comet impacts have occurred on Earth in approximately 30 Myr cycles.
Galactic Dark Matter Theory
A new theory posits that clumps of dark matter collected in a thin disc at the Galactic center can also cause similar perturbation and similarly send Oort comets on impact paths to Earth, the Sun, and other planets. According to this theory both of these perturbation event types — Galactic gravitational tidal forces, which are generated by star clusters, and Galactic dark matter disc concentrations — indicate that Earth's unexplained catastrophic comet impacts, and their related mass extinctions, have been precipitated by these extraterrestrial forces, especially dark matter, and have sent Oort comets spinning out of their cloud into erratic orbits directed toward the heart of the Solar system.
More about oort comet cloud, Comet, longperiod comet
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