giant planets


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giant planets

The planets Jupiter, Saturn, Uranus, and Neptune, which have diameters between 3.9 and 11.2 times that of the Earth and masses of between 14 and 318 Earth masses. They orbit the Sun at mean distances ranging from 5.21 AU for Jupiter to 30.06 AU for Neptune in periods from 11.86 to 164.79 years. All have low densities – from 0.7 to 1.8 times that of water – and are probably composed largely of hydrogen in its molecular or metallic state. Their visible surfaces are thought to be clouds of ammonia or methane. They all have planetary ring systems and share at least 150 satellites between them (see Table 2, backmatter).

giant planets

[¦jī·ənt ′plan·əts]
(astronomy)
The planets Jupiter, Saturn, Uranus, and Neptune.
References in periodicals archive ?
As Jupiter moved inward, however, gravitational perturbations from the giant planet would have swept the inner planets (and smaller planetesimals and asteroids) into close-knit, overlapping orbits, setting off a series of collisions that smashed all the nascent planets into pieces.
However, the water abundances in the giant planets of our solar system are poorly known because water is locked away as ice that has precipitated out of their upper atmospheres.
In order to understand how giant planets form astronomers want to know how enriched they are in different elements.
In order for the asteroids to pass sufficiently close to the white dwarf to be shredded, then eaten, they must be perturbed from the asteroid belt - essentially pushed - by a massive object like a giant planet," Dr Farihi said.
Heller and Barnes show that a moon needs to be roughly the mass of Earth to maintain an atmosphere and a magnetic field that could deflect deadly radiation from the giant planet next door and other sources.
Juno's launch is scheduled for August 5 and will take five years to reach the giant planet.
Previously, the only gas giant planet found to travel around a star in a near circular orbit, at three Earth-Sun distances, was the outer planet of the 47 UrsaMajoris system.
The research completely contradicts the widely held assumption that it takes at least one million years for gas giant planets like Jupiter and Saturn to evolve.
This single, coherent review of the theory behind extrasolar planet formation and interaction systematically covers all aspects of the topic, including different formation processes, planet-planet scattering, giant planets and brown dwarfs.
The currently accepted theory on how giant planets in our solar system formed, known as core accretion, states a planet is formed around the young star in a protoplanetary disk made primarily of hydrogen, helium, and particles of ices and dust composed of other chemical elements.
We have to revisit planet formation and migration models of giant planets, especially "hot Jupiters," and investigate how they're formed.
But when Nesvorny simulated the interaction, he found that Jupiter and Saturn usually expelled the ice giant, leaving behind three giant planets instead of the four currently found in the outer solar system.