Regina Barber

Like many scientists out there, he would love to find out what exactly dark matter is.

And a new clue just dropped.

It's called Cloud 9.

Cloud 9 is a failed galaxy.

It's a dark matter halo with a cloud of gas devoid of stars.

It's on the outskirts of a beautiful spiral galaxy, M94.

But what's a dark matter halo?

And while it may be an underachiever, Cloud 9 is a big deal.

The current model of our universe predicts this kind of dark matter halo exists, one that didn't help make a galaxy or stars.

But this is the first time astronomers have observed one.

Today on the show, why this failed galaxy could be the key to finding out one of astronomy's biggest mysteries.

Answering, what is dark matter?

I'm Regina Barber, and you're listening to Shortwave, the science podcast from NPR.

I'm talking with Andrew Fox and Gagan Deep Anand, two astronomers from the Space Telescope Science Institute in Baltimore, Maryland.

And you two were on the team that found this dark matter halo.

First of all, Andy, how did you feel when you realized what you found?

And Deep, can you help our listeners understand what is a dark matter halo?

Why is this such a big deal?

Okay, so Andy, can you help explain this Lambda CDM model and how it really tells us how galaxies are being put together?

How big are we talking about?