What is gravity?

Gravity is the mysterious force that makes everything fall towards the Earth. It turns out that all objects have gravity. It's just that some objects, like the Earth and the Sun, have a lot more gravity than others. How much gravity an object has, depends on how big it is: To be specific, how much mass it has. It also depends on how close you are to the object. The closer you are, the stronger the gravity.

Isaac Newton

Gravity was first mathematically described by the scientist Isaac Newton. His theory is called Newton's Law of Universal Gravitation. Later, Albert Einstein would make some improvements on this theory in his Theory of Relativity.

Why is it important?

Gravity is very important to our everyday lives. Without Earth's gravity we would fly right off it. If you kick a ball, it would fly off forever. While it might be fun to try for a few minutes, we certainly couldn't live without gravity. Gravity is also important on a larger scale. It is the Sun's gravity that keeps the Earth in orbit around the Sun. Life on Earth needs the Sun's light and warmth to survive. Gravity helps the Earth to stay just at the right distance from the Sun, so that it's not too hot or too cold.

Weight

Weight is the force of gravity on an object. Our weight on Earth is how much force the Earth's gravity has on us and how hard it is pulling us toward the surface.

Do objects fall at the same speed?

Yes, this is called the equivalence principle. Objects of different masses will fall to the Earth at the same speed. If you take two balls of different masses to the top of a building and drop them, they will hit the ground at the same time.

Fun facts about gravity

* Ocean tides are caused by the gravity of the moon.

* Mars is smaller and has less mass than Earth. As a result it has less gravity. If you weigh 100 pounds on Earth, you would weigh 38 pounds on Mars.

- (Ducksters)