Question: Why does the earth move around the sun?

Eoin Carley answered on 13 Nov 2014:

This is a nice question and one that you’ll come across in school. The simple answer is….gravity! Gravity keeps us firmly on the ground, it also keeps the planets in motion. You can do an experiment yourself….tie a ball (or anything slightly heavy) to the end of a string and spin it around above your head. You’ll notice that as you spin the object it exerts a tug on your arm – this is because the object is trying very hard to escape its circular motion, and you have to pull back to keep it spinning. This is what happens with the Sun and Earth, the Earth is in a constant state of trying to get away from the Sun, but the Sun ‘pulls’ at the Earth using gravity to keep it in orbit. This is the way ‘centripetal forces’ work, weather it’s you spinning a ball, or stars keeping planets in orbit. It’s the very same physics!