Why does Saturn float but Jupiter sink?
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Question by @VoidERROR404DOORS — thank you!
Saturn and Jupiter are both gas giants, made mostly of hydrogen and helium. But Jupiter has about 3.3 times Saturn's mass while being only about 1.2 times as wide, because its stronger gravity squeezes its gas much tighter. That gives Jupiter an average density of about 1.33 g/cm³, more than water (1.00), while Saturn's is only about 0.69 g/cm³. Pump even more gas into a planet like Jupiter and it would barely grow: it would just get squeezed tighter.
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Transcript
- Sef Void Error 404 Doors asks: why does Saturn float, but Jupiter sink?
- Sef Easy! Jupiter's made of heavier stuff.
- Tiggy Nope. Both are mostly hydrogen and helium.
- Tiggy But Jupiter has over three times Saturn's mass, and it's only a bit wider.
- Tiggy Its stronger gravity squeezes the gas tighter, so it's denser than water.
- Sef So more gas makes it bigger?
- Tiggy Barely. It just gets squeezed even tighter.
Sources
- NASA NSSDC: Jupiter Fact Sheet nssdc.gsfc.nasa.gov
- NASA NSSDC: Saturn Fact Sheet nssdc.gsfc.nasa.gov
- NASA Science: Saturn Facts science.nasa.gov
- NASA Science: Jupiter Facts science.nasa.gov
- Helled, Movshovitz & Nettelmann (2022), The nature of gas giant planets (review chapter, Planetary Systems Now) arxiv.org
- OpenStax Astronomy 2e (Rice University): The Giant Planets openstax.org
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