Just How Big Are Neutron Stars, Anyway?

I know, I know, somewhere between 10 and 20 miles. We've known how big neutron stars are for a while. Well, we've roughly known, as it turns out, we don't know their size accurately enough to really figure neutron stars out. We need an exact figure, because an exact figure will tell us exactly how dense they are, and that is an important problem for particle physics. We don't know how matter behaves when pushed to the absolute limits of density, and that's what neutron stars are. They're not black holes, the laws of physics still apply, and it's possible to learn what goes on inside them. All we need to finish the neutron star puzzle (okay, probably not) is an exact radius. And luckily for physicists, an instrument called NICER (Neutron Star Interior Composition Explorer), attached to the International Space Station, will answer these big questions this summer.

So, that's something to look forward to. I don't have any spectacular conclusions, since we don't know anything yet, I just thought this was a neat article.