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A gas planet is a planet made largely of gas, such as a gas giant. Gas giants are well known, i.e., Jupiter and Saturn, but smaller gas planets (gas dwarfs) have been recently discovered among extra-solar planets (gas dwarfs). There is no consensus threshold regarding which planets should be termed gas planets: presumably requiring gas-to-core ratio (GCR, in this case, core meaning the solid part of the planet) of at least 1 or at least few times that. Earth's GCR is about a millionth. Those of Jupiter and Saturn are unclear because of the unclear size of any rocky core (and because interior liquid volatiles present additional semantic issues) but certainly well above 1.