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Least dense exoplanet

Least dense exoplanet
Who
HAT-P-1b
Where
Not Applicable
When
01 January 0001
HAT-P-1b, 450 light years away, is a gas giant around 1.38 times the diameter of Jupiter, but with only half the mass of Jupiter. This gives it a density of only around one quarter that of water. If there was an ocean large enough HAT-P-1b would float in it, just like Saturn, only it would float around three times higher.