If the Earth is orbiting the sun and the sun is moving around the galaxy, and the galaxy itself is moving through space, why is it, with so many different speeds, that the planets’ orbits are so stable?

Question

With so much going on gravity-wise, it blows my mind that even with the solar system moving around the galaxy, everything stays so perfectly in place.

In: 8

Answer 1

Their orbits might actually not be stable over millions of years: see [this video I made about how Mars could collide with the Earth](https://www.youtube.com/watch?v=zRX3ixS1wMg)!

There are lots of ways planets could be arranged that wouldn’t be stable, and they could be affected by passing other stars too (though this is quite unlikely as the distances between stars are enormous and gravity gets weaker the further away they are), so perhaps the best explanation of why the Earth’s orbit is stable is that we’re here to see it. If it wasn’t, we might have crashed into another planet or the Sun by now, and we wouldn’t have evolved and invented Reddit.