How strong is the gravity on Saturn?

Although Saturn is much larger than Earth, its surface gravity is only a little more than the surface gravity on Earth. This is because Saturn is made up of gases and is not solid like Earth. This makes Saturn very light for its size. Actually, Saturn has the lowest density of all the planets in our Solar System, even lower than the density of water. This means that if you could find a bathtub big enough, Saturn would float (though it would leave a terrible ring around the tub).

The surface gravity on Saturn is about 107% of the surface gravity on Earth, so if you weigh 100 pounds on Earth, you would weigh 107 pounds on Saturn (assuming you could find someplace to, well, stand). Of course, that brings up the question of what we mean by "surface" when we're talking about "surface gravity". Here on Earth, we have a solid surface at which to measure it, but planets like Saturn and Jupiter have no solid surface - they are gas giants. We have to pick a "surface." The standard way of doing this is to define the surface as the radius at which the atmospheric pressure is equal to that at the surface of the Earth, known as "1 atmosphere," or "1 bar." We use this same standard to define the radius of the planet.

Now, if we're being really accurate about things, the gravity you'd feel at the "surface" of Saturn would actually depend on whether you were near the poles or the equator. Everything we've told you so far is accurate for near the north or south poles of the planet. If you were to find a place to stand near the equator, however, you'd actually feel a little lighter, because Saturn's spin is enough to offset some of the pull of gravity through centrifugal force. If you weigh 100lbs on Earth and 107lbs near Saturn's poles, you'd weigh closer to 91lbs near Saturn's equator. Incidentally, this also works for the Earth - if you weigh 100lbs at the North and South Poles, you'd weigh 99.8lbs when standing on the equator!


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