Long-period Comets
The very bright, long-period comet C/1996 B2 (Hyakutake). This image was taken by Michael Brown and Chris Fluke using the 40 inch telescope at Siding Spring Observatory on 25 February 1996.
long-period comet
Comets that have orbital periods greater than 200 years.
luminosity ...
LONG-PERIOD COMET - Comets with orbital periods longer than 200 years, often with highly elliptical orbits highly inclined to the ecliptic.
long-period comet
A comet with an long orbital period around the Sun. The majority of comets discovered each year are long-period comets which had not been previously documented.
Long-period Comet - A comet with an orbital period of 200 years or longer ...
Long-period comets are believed to originate in a distant cloud known as the Oort cloud (after the Dutch astronomer Jan Hendrik Oort who hypothesised its existence).
A long-period comet discovered in November 1957, by Belgian astronomers Silvain Arend (1902-1992) and Georges Roland (1922-1991). It reached perihelion (0.32 AU) on April 8, 1957, passed within 0.
Such long-period comets usually are seen once and then disappear for thousands of years. On the other hand, short-period and intermediate-period comets like Comet Halley stay within the orbit of Pluto for most of their orbits.
Apart from long-period comets, only four known objects have orbits which suggest that they may belong to the Oort Cloud: 90377 Sedna, 2000 CR105, 2006 SQ372 and 2008 KV42.
What of the long-period comets? How do we account for their apparently random orbital orientations?
Hale-Bopp is a long-period comet that was discovered in 1995 and that reached perihelion in Spring, 1997.
Long-period Comets (comets with an orbital period over 200 years and up to 30 million years): 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.
astronomers independently reported finding evidence that one or more large planets or brown dwarfs gravitationally bound to our Sun, Sol may be perturbing the orbits of two different groups of long-period comets at the outer reaches of the Oort ...
long-period comets and one-apparition periodic comets receive only a provisional designation -- there is no equivalent of the Roman numeral designation.
The Oort cloud is the source of long-period comets and possibly higher-inclination intermediate comets that were pulled into shorter period orbits by the planets, such as Halley and Swift-Tuttle.
The Kuiper belt acts as a reservoir for these in the same way that the Oort cloud acts as a reservoir for the long-period comets.
It was also believed that nearly all long-period comets that move inside Jupiter onto Earth-crossing orbits were nudged by the gravity of a passing star, and the same was thought to apply to short period comets from the inner Oort cloud too.
Farther still is the Oort Cloud, believed to be the source of extremely long-period comets (Hale-Bopp, for instance).
Comets are generally divided into short-period comets (those with periods of less than 200 years) and long-period comets (those with periods of more than 200 years).
The long-period comets may have an aphelion well outside the orbit of Pluto and can be inclined at all angles to the plane of the ecliptic. These are sometimes thought of as belonging to Jupiter's family. B. G.
The analysis of long-period comets led the Dutch astronomer Jan Oort to hypothesize the existance of a cloud of icy objects existing far outside the solar system but well within the Sun's gravitational influence.
The orbits of the long-period comets are not confined to a plane, like the orbits of the planets, and these comets can appear in any part of the sky.
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.
The hypothetical Oort cloud, which acts as the source for long-period comets, may also exist at a distance roughly a thousand times further than the heliosphere.
planet), it sees the sun and major planets essentially as a single object of summed mass, and the center of this mass (called the barycenter of the solar system) is offset somewhat from the sun; "original" and "future" orbits of long-period comets ...
It is currently thought that this is the location where all comets originate, and it is the current origin of long-period comets. The way they enter the inner solar system is by gravitational pushes usually caused by a passing star.
54 AU, Uranus's is 19.19 AU, and Neptune's is 30.07. The Kuiper belt of planetoids ranges from 30 to 50 AU. Finally, the Oort cloud, which gives birth to the long-period comets, is more than 100 AU from the Sun.
visitors into the inner Solar System and they do not generally fall in orbits in the same plane as that of Earth, but there is nothing to rule out the possibility that one might collide with the Earth. The impact velocity of a long-period comet would ...
are classified as Cubewanos in the main belt and scattered disk objects in the outer fringes.
Oort cloud objects, currently hypothetical, with orbits lying between 50,000 and 100,000 AU. This region is thought to be the origin of long-period comets.
The first such comets were discovered in the Kuiper cloud in 1992; by 1996, 31 had been found. The Oort cloud accounts for long-period comets, such as Halley's and the Swift-Tuttle (with a period of 130 years), ...
Hale-Bopp comet (NASA Thesaurus) Long-period comet discovered July 23, 1995; designated C/1995 O1. half life (NASA Thesaurus / NASA SP-7, 1965) The average time required for one half the atoms in a sample of radioactive element to decay.
 See also: Period, Comet, Orbit, Solar, Solar System
  
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