- one of the four planets in our solar system that are composed chiefly of hydrogen and helium, namely Jupiter, Saturn, Uranus, and Neptune
C20: coined by James Blish (1921–75), US science fiction writer
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Examples from the Web for gas giant
There was a gas-giant planet, a mere fifteen million miles away.
The gas-giant planet far behind, and the only inner one on this side of the sun, would return their pulses only after minutes.
The gas-giant planet outward from the sun was a perceptible disk instead of a diffuse glow.
It made for a rendezvous over a pole of the gas-giant planet which was the fourth planet from Kandar's sun.
Then the shining cloud-bank of the gas-giant planet went black.
- 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. Also called Jovian planet Compare terrestrial planet.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.