Katia Riddle

I'm ready for it.

Exactly.

Which, you know, I grew up learning was Pluto.

But unfortunately, it's since been kicked out of the major planet guild.

There's a lot of beef, a lot of baggage.

I'll be telling you about Neptune today and how one of its moons could help us fill in the gaps of our solar system's origin story.

But I promise it'll still be fun.

And Gina, you're also telling us another reason that the northern lights are awesome.

Okay, Gina, Scott, I'm sure you've heard a lot about Neptune, but I bet you don't know much about its moons.

Did you know that it has 16 of them?

You probably did.

No, I did not.

I knew it was a lot, but I didn't know it was like 16.

There's been questions about one specifically called Nereid for decades.

Researchers have been wondering whether this moon was formed right in Neptune's orbit or if it's an interloper from elsewhere.

Well, for starters, Nereid has a really unusual orbit.

It's stretched into this elongated oval shape.

For years, that highly eccentric orbit led researchers to speculate that it was not formed around Neptune.

Moons that are born, so to speak, around a planet tend to travel in a kind of regular circular path.

But now we're able to look more closely at Nereid's composition and see evidence that despite this weird orbit, it is more consistent with a moon that formed around Neptune than one that was captured from elsewhere.