gas giant

[ gas jahy-uhnt ]

noun

, Astronomy.

1. a giant planet composed mostly of hydrogen and helium: the two gas giants in our solar system, Jupiter and Saturn, are sometimes called failed stars because their composition is similar to that of stars, but this is largely considered misleading, as gas giants, unlike brown dwarfs, do not form as stars do. Compare ice giant ( def ).

gas giant

noun

1. one of the four planets in our solar system that are composed chiefly of hydrogen and helium, namely Jupiter, Saturn, Uranus, and Neptune

gas giant

1. A large, massive, low-density planet composed primarily of hydrogen, helium, methane, and ammonia in either gaseous or liquid state. Gas giants have swirling atmospheres primarily of hydrogen and helium, with no well-defined planetary surface; they are assumed to have rocky cores. They are also characterized by ring systems, although only Saturn's is readily visible from Earth. Our solar system contains four gas giants: Jupiter, Saturn, Uranus, and Neptune. The majority of extrasolar planets discovered so far are the size of the solar system's gas giants, although they orbit their stars much more closely and may differ in composition from ours.
2. Also called Jovian planet
3. Compare terrestrial planet

Word History and Origins

Origin of gas giant¹

First recorded in 1950–55

Word History and Origins

Origin of gas giant¹

C20: coined by James Blish (1921–75), US science fiction writer

Example Sentences

It will get a gravity assist by sling-shotting around Mars early next year, then boomerang back around Earth in late 2026 before zooming toward the gas giant and its icy, dynamic moon.

From Los Angeles Times

Scientists have advocated for a Europa mission for decades, ever since NASA’s Galileo probe found that the moon likely has a subterranean global ocean, heated by Jupiter’s gravitational forces compressing and stretching the moon’s core as it orbits the gas giant at break-neck speed.

From Los Angeles Times

Once Clipper arrives at Jupiter, it will orbit the gas giant 80 times over the course of four years, making 49 Europa flybys, as close as 16 miles from the surface, to collect data from pole to pole.

From Los Angeles Times

Companies whose futures depend on plastic production, including oil and gas giant ExxonMobil, are trying to persuade the federal government to allow them to put the label “recyclable” on bags and other plastic items virtually guaranteed to end up in landfills and incinerators.

From Salon

Its red hue, which is due to atmospheric chemical reactions, stands in stark contrast with the gas giant's other pale clouds.

From Science Daily