SP7 - Astronomy Flashcards
What is the only force acting on objects orbiting around the Sun to keep them in their orbits
Their weight due to the Sun‘s gravitational field
Why is there only this one force on an object orbiting the Sun?
Everything is moving in (roughly) a circle around the Sun with only this one force on it because things want to move in a straight line unless acted upon by a resultant force and the weight of each due to the Sun is the resultant force. This force acts at a right angle to the motion (towards the centre of the Sun), pulling them around. This is centripetal force
Why do planets move at different speeds?
The ones further out move slower because they are further from the Sun than the one before, so the force from the Sun is weaker
(If the force from the Sun was constant, then ones further out would have to move faster, like satellites around the Earth)
List the contents of the Solar System
Sun, Mercury, Venus, Earth (+ moon), Mars (+ moons), asteroid belt, Jupiter (+ moons), Saturn (+ moons), Uranus (+ moons), Neptune (+ moons), the Kuiper Belt including Pluto (+ moon)
