Andrew Fox

But the cool thing about this model is that it predicts there are smaller halos, smaller halos that are beneath the scale that can form a galaxy, essentially failed galaxies, things that didn't quite have enough mass

to form a galaxy, emit light, and become like any other galaxy we can see.

Those smaller halos are called relics.

That's a technical term, but you can think of it as a relic, a leftover from this time when galaxies formed.

But there were some leftover clouds that were not massive enough to form galaxies.

And this is part of this theory, the CDM theory.

So this relic we've been studying called Cloud 9 is about a kiloparsec across.

That's the unit astronomers use.

That's about 3,000 light years.

The Milky Way would be, I don't know, maybe 50 kiloparsecs or 150,000 light years across.

So this object is much smaller than the Milky Way.

It's small and it's dense with no stars in it.

But so we think of these relics as the leftover clouds that didn't quite make it to become galaxies.

And they've just been hanging out there in the universe, but they're very hard to observe.

And that's why we had to look really to very deep levels, look with very sensitive imaging with the Hubble telescope to actually confirm this thing and show that it had no stars in it.

And that's really the side of this story we're most excited about, is that these objects have been predicted by theory.

They come out of this Lambda-CDM theory.

But with Cloud9, we finally have a chance to observe one and see what its real properties are like.

Yeah, that's right.

There have been other candidates.