Swarm of billions of comets thought to surround the Solar System between 2000 and 20 000 AU from the Sun. First proposed by E. Öpik in 1932 and later developed by J. Oort in the 1950s. Its existence is based on studies of long-period comet orbits, which seem to have their aphelia in this zone.
Spherical halo of material surrounding the solar system, out to a distance of about 50,000 A.U., where most comets originate.
A Dutch astronomer, Jan Oort, observed in 1950 that no comet had ever been seen with an orbit indicating that it came from interstellar space, nor did comets seem to have a preferred direction of origin. He therefore hypothesized that the Sun is surrounded by an immense cloud of comets - the Oort Cloud - extending from about 1200 times Pluto's distance from the Sun out to about 3 light years. (The nearest star, Proxima Centauri, is 4.25 light years away.) So distant that its members are only weakly bound to the Sun, the Oort Cloud is occasionally disturbed by passing stars that fling bits of it either into the inner solar system as comets or out into interstellar space. The Oort Cloud is thought to contain as many as a trillion comets, but since they are so small and at such a great distance, there is no direct evidence that it actually exists at all.
a vast collection of bodies made up of rock and ice that orbit the Sun at a distance starting in the region beyond the orbit of Pluto and extending out to nearly 1.5 light-years or 50,000 A. U. Unlike the bodies of the Solar System, which orbit the Sun in roughly the same plane, the Oort cloud objects form a vast sphere around the Sun. It is estimated that billions of objects exist in this region, and there is evidence that this is the place where most comets originate.
The Oort Cloud is a massive spherical cloud of rocks and dust that may surround our solar system. It is thought to exist between 50,000 to 100,000 A.U. from the Sun and may contain anywhere from billions to trillions of comets. It has not been directly observed, its existance is inferred from the orbits of the long period comets.
A huge cloud thought to surround our solar system that is home to large quantities of dust that are frozen and covered with ice. Area serves as the birthplace of comets.
a large spherical cloud of billions to trillions of comets surrounding the Sun at distances between roughly 50,000 to 100,000 A.U. from the Sun. It has not been directly observed; its presence is inferred from the behavior and orbits of the long period comets.
Proposed as the source of comets, the area of debris spanning a distance of one to two light years out from the Sun, and surrounding the solar system.
An spherical envelope of small bodies theorized to surround our Solar System at 0.1 to 1 lightyear, and proposed to be the source of the longest-period comets.
A vast spherical halo of icy objects around the solar system; the repository of long period comets
Reservoir of long period comets that occupies a spherical region of about 50,000 AU radius around the Sun.
is the name for widely accepted theory on the origin of comets. Dutch astronomer J. H. Oort proposed that a spherical cloud of comet nuclei surrounds our solar system at a greater distance from the Sun. It is thought that the gravity of a passing star may cause a comet in the cloud to begin its long fall toward the Sun.
The spherical region of the outermost Solar System which is home to long-period (orbital periods 200 years) comets. This region was postulated by Jan Oort to explain the observed distribution of long-period comets.
A cloud of objects up to 50,000 AU from the Sun. There are likely billions of comets in the Oort Cloud. The Oort Cloud is the source of non-periodic comets. Non-periodic comets are comets that swing around the Sun once and are flung off into space, never to return.
A large swarm of comets theorized to orbit the sun in the neighborhood of 50,000 AU.
A spherical cloud of trillions of comets extending about halfway to the nearest stars and weakly bound by the Sun's gravity. Long-period comets originate from the Oort cloud.
trillions of incipient objects surrounding the Solar System in a 50,000 AU (radius) sphere; source of long-period comets.
A cloud of cometary debris in Pern's solar system. Every 200 or so years, its orbit intersects Pern, bringing with it the Thread spores.
large assembly of comets surrounding the Sun at great distance.
A theoretical shell of comets that is believed to exist at the outermost regions of our solar system. The oort cloud was named after the Dutch astronomer who first proposed it.
The cloud of rocks and dust that surrounds our solar systems. The Oort cloud is believed to contain long-period comets.
A vast, roughly spherical reservoir of comets at the outer limit of the solar system. Postulated by Jan Oort in 1950, the Oort Cloud is thought to be the source of the long period comets.
a cloud of cometary nuclei that surrounds the sun at a distance of many thousands of astronomical units.
The Oort Cloud is a cloud of rocks and dust that may surround our solar system. This cloud may be where long-period comets originate. The Oort Cloud was named for Jan H. Oort, who proposed its existence in 1950. It has been hypothesized that the Oort Cloud is responsible for the periodic mass extinctions on Earth.
A hypothetical huge collection of comets orbiting the sun far beyond the orbit of Pluto; perturbations (as by other stars) can upset a comet's orbit and may send it tumbling toward the sun.
The spherical region around the Sun thought to contain a large number of cometary bodies.
A halo of debris left over from the formation of the Sun and planets that surrounds our Solar System. The Oort Cloud has a diameter of about 100,000 A.U. and contains some 100 billion fossils of Solar System formation. It is likely that comets originate from this cloud.
The theoretical shell of comets circling the Solar System at approx. 1 light year.
a spherical shell of cometary bodies believed to surround the sun far beyond the orbit of pluto and from which some are dislodged when perturbed (as by a passing star) to fall toward the sun. (Named for Dutch astronomer Jan Oort)
A vast spherical region in the outer reaches of our solar system where a trillion long-period comets (those with orbital periods greater than 200 years) reside. Comets from the Oort Cloud come from all directions, often from as far away as 50,000 astronomical units.
The Oort cloud, (IPA: BrE , AmE ), alternatively termed the Ã–pik-Oort Cloud (-, like with a rounded /e/), is a postulated spherical cloud of comets situated about 50,000 to 100,000 AU from the Sun. This is approximately 2000 times the distance from the Sun to Pluto or roughly one light year, almost a quarter of the distance from the Sun to Proxima Centauri, the star nearest the Sun.