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Gravity is the pull that every object exerts on other objects. The more massive an object, the greater the gravitational pull it can exert on another object. The further the distance between two objects, however, the smaller the gravitational pull. It is gravity that holds planets and stars together and gives them their nearly spherical shape, and it is the gravitational pull of the Earth that keeps things – such as ourselves – from floating off into space. It is the Sun’s gravitational attraction that holds the planets in their orbits.

When we weigh an object, we are measuring the Earth’s gravitational pull on it. On a different planet, the same object could have a different weight, because the planet’s mass and radius might be different than the Earth’s. On Mercury, the gravitational force on an object – its weight – would be only 37% as large as on Earth. For example, if you weighed 600 N (135 lb) on Earth you would weigh only 220 N (50 lb) on Mercury.


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The Sun is far more massive than any of the planets in our Solar System. In fact, if you weighed 600 N on Earth, you would be about 28 times as heavy – about 168,000 N, or 37,500 lb – on the surface of the Sun! To determine how much you would weigh on another planet, use the CERES Solar System Weight Calculator by clicking on the image above.