Planets move in elliptical orbits because they're constantly being pulled and pushed by gravity, like a fun game of tug-of-war!
Imagine you're on a swing. When you pull your legs back, you go higher, that’s like when a planet gets closer to the Sun. But then you let go, and you swing forward again, like when a planet moves farther from the Sun. This is what happens with planets: they’re pulled by gravity (from the Sun), but they also have speed, so they don’t just fall straight in, they keep moving forward.
Like a ball on a string
Think of a planet as a ball tied to a string, and the Sun is you holding the other end. If you spin the ball around, it goes in a circle, that’s a circular orbit. But if you let go of the string just a little bit, the ball swings out, making an ellipse, like an oval.
Planets don’t have perfect strings, they have gravity and speed, so their paths are more like stretched-out circles: ellipses! That's why we see them moving in elliptical orbits instead of perfectly round ones.
Examples
- Imagine going on a swing: you move higher when you push harder, and lower when you slow down.
- The Moon orbits Earth in an oval shape instead of a perfect circle because of the pull of gravity.
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See also
- Why do planets orbit? (With Dan Burns)?
- How does gravity work to keep planets in orbit around stars?
- How do we find new planets?
- How Do We Know What Air is Like on Other Planets?
- How big is the Solar System?