Gravity on different planets If we were to travel to other planets, one of the first things we would have to learn would be how to walk on its surface, because on the surface of different planets, we would be subject to differing levels of gravity. Some planets have a stronger gravity than Earth's, some have weaker. On a planet with a weaker gravity, we would be able to carry more mass and jump higher. (Look Ma! I'm Superman!) On a planet with a stronger gravity, we might be forced to our knees by just our own weight. (ACK! Kryptonite!) To calculate the surface gravities of varying planets, we can use the following equation, which is the simplified form of Newton's gravitational law : The surface gravity (a) on a planet is equal to the Universal Gravitational Constant (G) multiplied by the planet's mass (M), divided by the square of planet's radius (r).  Different planets have different masses and radii. Thus, their surface gravities vary. By knowing the mass and the radius of a planet, we can calculate its surface gravity. The table below lists the results of our calculations.

Calculated Surface Gravities of Planets in our Solar System

 Normalized Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto Mass* 0.05 0.82 1 0.11 318 95 15 17 0.0021 Radius* 0.38 0.95 1 0.53 11 9 4 4 0.1785 Surface Gravity * 0.35 0.91 1 0.39 2.63 1.17 0.94 1.06 0.07
* in proportion to Earth's

 "The surface gravity of Earth has a value of 9.8 m/sec2 and is commonly referred to as g."         In the above table, you'll notice that every variable was represented in proportion to Earth's value. For example, Mercury's surface gravity is 0.35 times of Earth's g, and Jupiter's surface gravity is 2.63g. Naturally, one would expect that if one were to throw a ball straight up with the same vertical velocity on different planets, the ball would reach different heights, as demonstrated in the simulation of Motion on Different Planets.