Let's Investigate!

The Earth’s axis is tilted relative to the plane of its orbit around the Sun so that the length of day varies with position on the Earth’s surface and time of the year, giving rise to the seasons. The Earth is one of eight (so far known) planets in our solar system which, along with many other smaller bodies, orbit the Sun in roughly circular paths, at different distances from the Sun and taking different times to complete an orbit. As seen from Earth, planets move in relation to the positions of the stars which appear fixed relative to each other. Galileo Galilei was the first scientist to find and describe evidence for the motions of the planets and their relative position to the Sun in the heliocentric model.