Orbits are not tidy circles but stretched ellipses, and a comet feels it. Diving toward the Sun it gains speed, then slows as it climbs back out, trading energy between motion and height all the way round.
Orbits are ellipses. As an orbiting body moves closer to the Sun it speeds up, and as it moves further away it slows down, because gravitational potential energy and kinetic energy convert into each other while the total energy stays the same.
Planets and comets orbit on ellipses. An orbiting body moves faster when closer to the Sun and slower when further away.
As it falls inward, gravitational potential energy becomes kinetic energy; the reverse happens on the way out, and the total energy is conserved.
Follow a comet round its elliptical orbit and watch its speed change with distance.
Four quick checks. Each correct answer earns XP and lights this skill on your star map.
The orbits of planets and comets are shaped like...
As a comet moves closer to the Sun, its speed...
As a comet moves further from the Sun, its speed...
Around the orbit, kinetic energy and gravitational potential energy...
Kinetic and gravitational potential energy convert into each other as the distance changes.
An orbiting body moves fastest when it is closest to the Sun and slowest when furthest away. As it falls inward, gravitational potential energy becomes kinetic energy, and the reverse happens as it climbs back out.
Unlocks once the four checks above are done. Worth more XP, written in the style of Paper 2.
A comet on a highly elliptical orbit moves fastest when it is...
As a comet falls inward toward the Sun, its gravitational potential energy...
Why does a comet slow down as it moves away from the Sun?
Elliptical orbits complete the Solar System strand. Keep the chain going.