Gravity in Space
Science: KS3, topic 3.5.17
Gravity in Space
Gravity is what keeps astronomical bodies in orbit. Without a gravitational force, we would float off into space, as would planets and moons.
The Earth and the Moon
- Larger masses will increase the gravitational force.
- Objects that are closer will have larger gravitational forces.
The Moon’s Orbit
- The Moon is a natural satellite and orbits the Earth.
- The Moon takes about 28 days to complete one orbit of the Earth.
- The Earth’s gravitational pull keeps the Moon in orbit.
Gravity and Tides
- The Moon’s gravitational pull is weaker than the Earth’s pull.
- However, the Moon’s pull is strong enough to cause tides.
- The Moon is getting further away from the Earth by about 3cm per year.
The Earth and the Sun
- The Sun weighs over 300,000 times the weight of the Earth.
- The Sun is our nearest star.
- The Sun’s gravitational pull keeps the Earth in orbit.
- The Earth takes about 365 days to orbit the Sun.
Test yourself on Gravity in Space
Why do we have tides?
Which of these are true of orbits?
The Sun weighs over 300,000 times more than the Earth and is very far away. Why can the Sun's gravitational pull still keep the Earth in orbit?
The Earth takes about 365 days to orbit the Sun. The Moon takes about 28 days to orbit the Earth. Which orbit takes the longer time to complete?