Satellites and moons
2 marks · EasyExplain why moons always orbit their planets rather than moving away into space.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
Because gravity from the planet pulls the moon towards it, preventing it from flying off into space.
Also accept: Gravitational force keeps moons in orbit.
Common mistakes: Magnetic force; Air resistance
Show mark scheme and worked solution
Marking points
M1 · 1 mark · States gravity pulls the moon towards the planet.
A1 · 1 mark · Clearly links gravity to keeping the moon in orbit/circular path.
Worked solution
Gravity from the planet always pulls the moon towards it. This force keeps the moon moving in a curved path (orbit), rather than allowing it to move in a straight line and escape into space.