What is gravity?
Gravity is the force that pulls objects with mass toward each other. It keeps us on the ground, holds the Moon in orbit around Earth and Earth in orbit around the Sun.
The more mass an object has, the stronger its pull, and the pull weakens with distance. Isaac Newton described this with his law of universal gravitation in 1687, explaining both falling apples and the orbits of planets with one simple rule.
In 1915, Albert Einstein's general theory of relativity gave a deeper explanation: mass and energy bend space and time, and objects move along these curves. Einstein's theory explains things Newton's could not, such as the slight shift in Mercury's orbit and the bending of light around the Sun.
Gravity around the solar system
Gravity on the Moon is about one-sixth as strong as on Earth, so a 60-kilogram person would feel as light as 10 kilograms there. On Jupiter, gravity is about 2.5 times stronger than on Earth.
Did You Know?
Gravity is by far the weakest of the four fundamental forces, but because it acts over huge distances and always attracts, it shapes stars, galaxies and the whole universe.