Force

Orbits

An orbit is the path an object in space travels around another. Lots of objects in the Universe orbit others. The Moon orbits the Earth.

Orbit of dwarf planets Pluto and Charon

Since ancient times, people have known about some rocks that could attract iron. When these rocks were rubbed on other types of metal, they had the power to make them attractive too. These items could also push each other away, repelling each other.

A dark grey and brow rock with a textured surface. On this, three metal nails are sticking to it. — Lodestone, one of a few minerals that are naturally magnetic.

Gravitational Lensing

Space is not flat. It is 3D, and we say that everything in it is held together on an imaginary surface we call spacetime. The idea of spacetime was put forward in Einstein's theory of relativity.

A white meshed grid against a black background. Three spheres of different size and mass sit on the grid, appearing to distort the grid beneath it. The largest sphere is yellow and causes the most distortion, with the next smallest being orange that causes less distortion. A red sphere is the smallest, with the mesh around it barely being distorted. — Artists impression visualising space-time being distorted by three spheres with different masses.

Gravity

Gravity is the name of the force that pulls objects together. It is a non-contact force. This means it acts on objects that are not touching each other.

A picture showing people appearing to float in the air inside of a NASA plane. — Experiencing microgravity on a NASA plane.

An illustration show the field of gravity around the Earth. A blue circle in the centre is labelled 'Earth'. There are black arrows spaced uniformly around the circle, with the arrowheads all pointing inwards towards the shape. — The pull of gravity around the Earth.

Johannes Kepler

Occupation

Astronomer, Mathematician, Scientist, Teacher

Year born

1571

Research Areas

Planetary motion, Optics, Geometry

A painting of Johannes Kepler. He is stood with a hand on his hip. There is a table in front of him with parchment papers and a globe placed on it.

Make Your Own Impact Crater

Impact craters are made when a space rock (called a meteorite or asteroid) hits a rocky planet or moon. The impact makes a round hole in the surface, called a crater.

Read more about Make Your Own Impact Crater

Explore Gravity

Use our simulator to investigate the effect of gravity on other worlds. Then use your measurements and a bit of maths to calculate the strength of gravity in each location across the Solar System!