[mewzilla]

Q: If the egg heads aren't sure how big these things are, how do they know how close they'll get? 🤔

[Bloody Sam Roberts]

Q: If the egg heads aren't sure how big these things are, how do they know how close they'll get?

Regardless of size, they are able to see where it has been...a year ago then 6 months then a month, etc. Simple math given its speed, trajectory and the influence of Earth's (and other planets') gravity.

Determining size is much more difficult.

[InABunkerUnderSF]

Q: If the egg heads aren't sure how big these things are, how do they know how close they'll get?

To measure their orbit, which tells you how close they'll come, all you need to see is a point of light over a period of several nights. To measure their size you need to either see a visible disk or know how light or dark the object is. If it's light colored it could be reflecting up to about 40% of the light that hits it. If it's dark it could be reflecting less than 10% of the light that hits it and could be huge and still look small and dim.

[bert]

[Vermont Lt]

Calculus.

There is no weight in space.