Thanks for reading and supporting Rebecca — much appreciated! Yeah it is mind-blowing. I think even astronomers who study these things all day every day are blown away by these things.

Astronomers measure these things in a variety of ways, but the simplest to think about is how we have two eyes spaced apart which gives us binocular vision, something called parallax so we have a visual sense of space in 3D. Astronomers can use Earth’s orbit to get images of stars from opposite sides of the orbit to estimate distances to objects, and from that estimate their size.

Here’s one of several Youtube videos that give a nice sense of size of some of these astronomical objects:

That one was part of a series, and you might want to check out all of them to get a full sense of scale… it is a fun mind-blowing experience! ;). Thanks again Rebecca! SD