Daniel Whiteson

Nobody knows what it is.

It's not very far away.

It's not very far away because these particles cannot go very far through the universe.

So if we're seeing them here on Earth and we're seeing them,

then they can't come from like all the way across the universe.

They have to be coming from our galaxy or one of the neighboring galaxies.

They can't go any further than that.

So they're in our cosmic neighborhood.

The challenge is they're rare.

We've seen like in decades of looking, we've seen a handful of these.

So we can't even like say, where are they coming from in the sky?

Are they all coming from the center of the galaxy?

Are they all coming from this one planet that's orbiting that star?

And this is like aliens shooting a message at us.

We can't even do that kind of pointing because we have a handful of them.

And the reason is that they're very hard to spot.

They hit the top of the atmosphere and they create a big shower of particles.

So one energetic particle turns into two with less energy, which turns into four, which eventually by the time it hits the ground is like a trillion particles.

A trillion?

Oh, trillions, absolutely.