What is Gravity

When we think of gravity, we tend to think of Sir Isaac Newton sitting under an apple tree: an apple falls on his head, and the idea of gravity is born. The story probably didn't ha happen quite that way, but Newton did observe falling objects, and he did wonder what mysterious force drew them to the ground and why some items seemed to fall faster than others. Newton's law of universal gravitation, published in 1687, holds that everything in the universe exerts a pull on other objects (called attraction), and the pull increases with mass and proximity.