giant planets


Also found in: Dictionary, Thesaurus.

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 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.
The study provides strong evidence that giant planets keep the material that forms debris disks in check.
Instead, the primordial solar system was a chaotic place, with the giant planets likely much closer to one another.
Zuluaga and his team at the University of Antioquia have gathered knowledge about the generation and maintenance of magnetic fields in terrestrial and giant planets and use it to predict the intensities of those magnetic fields.
But last October, when astronomer Hal Levison presented what he called a "slightly radical" mechanism for building the solar system's giant planets, he was ready.