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Jupiter, the king of the planets, is much larger than our planet Earth. Astronomers tell us it's about 318 times as massive (heavy) as Earth. Mass, however, does not mean volume (size), and it's quite possible for something like a small rock to have more mass (weight) yet much less volume (or size) than an inflated balloon. But in Jupiter's case, its volume is even more impressive than its mass, the volume being some 1,300 times more than the Earth's.

Anyhow, what would our weight be on Jupiter, presuming we could stand on its surface? First of all, let's come back to Earth and pretend that our planet Earth all of a sudden became 318 times as massive - equaling Jupiter's mass - but retained its same size. In this scenario, you'd weigh 318 times as much. Does that mean, then, that you'd weigh 318 times as much on Jupiter? The answer would be yes, if Jupiter's size were the same as Earth's. But since Jupiter's size doesn't come close to matching Earth's, that complicates the picture a bit - but not unduly so.

Now that you know how much more massive Jupiter is than Earth, you must also find out Jupiter's radius as compared to Earth's. It's about 11 times greater.* So on the surface of Jupiter, you would be 11 times further away from the center of the planet than you are on Earth. And the further you are from the center of mass, the weaker the pull of gravity. To find out how much weaker, square the radius (or multiply the radius by itself) to come up with a figure of 121. Then divide Jupiter's mass (318) by the square of its radius (121) to find out that you'd weigh about 2.6 times as much (318 divided by 121).

*Given that Jupiter's radius is 11 times the Earth's, then its surface area is 121 times greater (11 x 11) and its volume is 1,331 times as great (11 x 11 x 11).

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