Fact of the day
Sunday, 27 September 2026
PlanetsSaturn
Saturn is less dense than water.
Saturn's mean density is about 0.69 grams per cubic centimetre, below the 1.0 g/cm³ of liquid water. It is a giant ball of mostly hydrogen and helium with a comparatively small dense core.
The often-repeated image of Saturn floating in a giant bathtub is a useful illustration of the number, although the planet's own gravity and immense size make the scenario physically impossible.
Its low density partly explains the planet's pronounced equatorial bulge: fast rotation, roughly a 10.7-hour day, flattens the visible disc noticeably.
Reference: NASA — Saturn Facts
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