Oort cloud

O0127700 (ôrt)n. A swarm of comets orbiting the sun at a distance of one to two light years, proposed as a source of comets that pass near the sun.

[After Jan Hendrix Oort (1900-1992), Dutch astronomer.]

Oort cloud

(ôrt, ōrt) A sphere-shaped mass of comets that makes up the outer edge of the solar system, surrounding the Kuiper belt and the planets. The more than 100 billion comets in this region orbit the sun at a distance of one to two light-years. Comets from this area that come into the inner solar system take more than 200 years to make one complete orbit. Compare Kuiper belt.

Thesaurus

Noun

Oort cloud - (astronomy) 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 sunastronomy, uranology - the branch of physics that studies celestial bodies and the universe as a wholeaggregation, collection, accumulation, assemblage - several things grouped together or considered as a whole

Translations

nube di Oort

Oort cloud

Oort cloud:

see cometcomet
[Gr.,=longhaired], a small celestial body consisting mostly of dust and gases that moves in an elongated elliptical or nearly parabolic orbit around the sun or another star. Comets visible from the earth can be seen for periods ranging from a few days to several months.
..... Click the link for more information. .

Oort cloud

(oort, ort) (Öpik–Oort cloud) A cloud of comets that move in orbits round the Sun with perihelia in the range 5–50 AU and aphelia in a zone with heliocentric distances between 30 000 and 100 000 AU, i.e. in a zone far beyond Pluto's orbit. Since the nearest star to the Sun – Proxima Centauri – is 270 000 AU away these comets can be perturbed by passing stars; this changes their orbits and send them in closer toward our Sun (or out toward the perturbing star). These perturbed comets have periods of hundreds of thousands of years. The Oort cloud is so distant that it acts as a refrigerated cometary reservoir.

The existence of a distant long-lived cloud of comets was first suggested in 1932 by Ernst Öpik. The same idea was proposed in 1950 by J.H. Oort who thought that comets originated from the disintegration of a planet some time in the early history of the Solar System. After this the major planets, Jupiter in particular, drove the majority of the comets either into the inner Solar System, where they decayed, or into the outer regions. Of this latter group 98% would have been lost from the Solar System, only 2% remaining in the Oort cloud. The number of comets in the cloud is uncertain but it could be somewhere in the range 10¹¹ to 10¹² with a total mass in the region of 10²⁸ grams. The orbits are oriented at random. A cometary cloud of radius 100 000 AU has a half life of at least 1.1 × 10⁹ years. The existence of the cloud shows up very clearly when the number distribution of comets is considered as a function of the reciprocal of the semimajor axes of the orbits. See also Kuiper belt.

Oort cloud

Oort cloud

Oort cloud

Oort cloud

Oort cloud:

Oort cloud

Oort cloud

Words related to Oort cloud

noun (astronomy) a hypothetical huge collection of comets orbiting the sun far beyond the orbit of Pluto

Related Words