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Comment by martincmartin | Hacker News Reader

In a uniform gravitational field, it isn't. On the earth's surface, acceleration due to gravity is 9.8 m/s^2, independent of the mass of the falling object. See Galileo's Leaning Tower of Pisa experiment.

https://en.wikipedia.org/wiki/Galileo%27s_Leaning_Tower_of_P...

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The field is not uniform though. So in theory, if you know the orbit and firld exactly, you can calculate it.

In the present case, I guess the precision with which one knows the orbit and other stuff (like the exact gravitational fiel of the earth) doesn't work out.

True. It turns out, it also applies for the two body problem, as long as one body is much more massive than the other.

https://en.wikipedia.org/wiki/Orbital_period#Small_body_orbi...

> Hopefully I'm not embarrassing myself with this question, but:

Yup, I'm kind of embarrassed :) I forgot that maintaining orbit is just a matter of falling at the same pace that the earth is falling away from you.

> maintaining orbit is just a matter of falling at the same pace that the earth is falling away from you

Perhaps a better visualization: moving sideways fast enough that you miss the earth? :)

If you've never tried it, I highly recommend playing Kerbel Space Program[1] (it works on Linux, Mac, and Windows!).

That game taught me so much about orbital mechanics, which led to rabbit holes of textbooks and videos[2].

The first big lesson KSP taught me was: why, when launching a rocket, you don't just go straight up but, instead, have to lean over pretty aggressively.

[1] https://store.steampowered.com/app/220200/Kerbal_Space_Progr...

[2] https://www.youtube.com/watch?v=dhYqflvJMXc

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