Given the formula for relativistic excess radius [0] as applied to Earth gives 1.478 mm [1], or 0.23173 parts per billion, anyone using at least 10 significant figures is wasting effort unless they’re also accounting for general relativity.
Naturally, I had already memorised the first 12 digits of π years before I found out about that.
I’d be surprised if NASA wasn’t accounting for GR as standard, what with Mercury etc., but for the rest of us, 10 sf should be enough.
Thank you for this comment! I remember the radius excess from undergraduate relativity, but for months I've been unsuccessfully looking for its name or a brief reminder of how it works. What luck!
Naturally, I had already memorised the first 12 digits of π years before I found out about that.
I’d be surprised if NASA wasn’t accounting for GR as standard, what with Mercury etc., but for the rest of us, 10 sf should be enough.
[0] https://www.physicsforums.com/threads/what-is-feynmans-exces...
[1] http://www.wolframalpha.com/input/?i=G%2A%28earth%20mass%29%...