[♪ INTRO] They might not be your typical UFOs,  but astronomers do occasionally discover unidentified objects floating  in the depths of space.

Take ORCs for example. While they might share a name  with creatures from fantasy books and tabletop adventures, they’re not some  kind of weird, scary extraterrestrial.

ORC is actually short for Odd Radio  Circle, and while we have a few clues to work with, the truth is,  we don't know what they are. In the grand scheme of astronomical  mysteries, ORCs are pretty new to the scene. As the name suggests, Odd Radio  Circles look like, circles.

And they’re visible in the radio  band of the electromagnetic spectrum. And they're odd! The first ones were spotted back  in 2019, and as of early 2023, we’ve only spotted six potential ORC candidates.

Four of those candidates are loners, and the other two form a sort of double  feature, connected by, like, a tail. And what’s odd about them  is that, as far as we know, they’re only visible at radio wavelengths. Usually, you see space stuff  emitting electromagnetic radiation, otherwise known as light, all over the spectrum.

But for some reason, ORCs are stuck in radio. And the reason could vary  depending on the ORC candidate. For example, one might be an  ancient supernova remnant.

And that double ORC might just  yet be another radio galaxy… a galaxy that just happens to be  emitting more radio waves than normal. The astronomers working on this puzzle don’t really consider those to be true ORCs. Because if we set those aside, we’re  left with three ORCs that all have another thing in common: each have  a galaxy smack dab in the middle.

Now, that could be a complete coincidence. When we look up into space, all of the  3D universe is flattened into our 2D sky. That’s probably why ORCs look circular too.

They’re most likely spherical…  or a long horn shape… but both of those look like  circles when you see them head-on. But the running hypothesis is that these  galaxies are the ORCs’ point of origin.. And there are a few competing hypotheses to explain what these  galaxy-encircling objects actually are.

One states that they were  born of two galaxies merging. Not only did all the stars and dust  smush together into one big galaxy, the two supermassive black  holes at their cores did, too. And that merger created a  huge explosion and shockwave that extended, like, a million  light years beyond the galaxy.

Another proposal states that  ORCs are shockwaves created after a galaxy goes through a phase  when it makes a bunch of new stars. All those baby stars create a kind  of stellar wind, blowing ever outward until something from beyond the  galaxy pushes back just enough to stop that wind from expanding. Either way, you get something  pretty darn spherical that will look like a circle from way over here.

But where do all the radio waves come from? Well, these shockwaves don’t just carry a  bunch of dust and gas along for the ride. They carry magnetic fields, too.

And eventually, those fields are sent  crashing into the intergalactic medium… the stuff between galaxies. That collision will accelerate  a bunch of electrons out there just minding their own business. And because electrons are charged particles, they’ll interact with the magnetic  fields in a very specific way.

They start spiraling around and around, emitting a kind of light  called synchrotron radiation. Synchrotron radiation can be  pretty much any wavelength, but its radio signal is way stronger. In fact, this radiation is one of  the dominant sources of radio waves throughout the universe.

Meanwhile, the synchrotron radiation  emitted at other wavelengths is so weak that we can’t really  detect those signals from Earth. In other words, ORCs might technically  be emitting other kinds of light, we just haven’t detected it yet. Researchers are currently analyzing data  from an all-sky survey called eROSITA to see if they can find  these ORCs emitting x-rays.

In which case, that would make them ORX-C…? OXARC…? Which isn’t as good as ORC,  but, you know, either of those.

Take them astronomers. I give those to you. But synchrotron radiation isn’t  the only potential explanation for our mysterious friends.

Some researchers claim that ORCs are  radio jets shooting out from black holes. Big cones of stuff emitting  radio waves as they’re flung away from the center of the galaxy. We see these sticking out of plenty  of galaxies throughout the universe, but they usually point out to the sides.

ORCs may be the very special, very rare case where they’re  pointed exactly, directly at us. But other astronomers dismiss  this hypothesis on the basis of “They’re just too darn round.” Sure, we’ve only discovered a handful of  these things, but not one is an ellipse. If ORCs are actually these super long  radio jets poking out of the galaxies, the chances are way more likely that our  vantage point would be just a little off-center.

We’d be discovering not O-R-Cs, but O-R-Es. So these mystery objects are  probably a new perspective on some familiar astronomical phenomenon. But that doesn’t mean there aren’t  some more…novel ideas out there.

One duo sitting over in SciFi Hypothesis Corner has suggested that ORCs are  the throats of wormholes. That one doesn’t seem to be taken very  seriously by the broader community, but hey, just wanted to let you  know about it, because that’s cool. The key to solving any of these  mysteries is going to be more data.

Looking closely at other wavelengths,  looking with even more sophisticated radio telescopes, and looking at the  data we’ve already got using new models. In time, these astronomical  UFOs may finally be identified. And when that happens, maybe  they’ll be a little less odd than astronomers first thought.

But maybe they’ll be something entirely new. I personally, though, would  keep the name either way. At least until we find some actual space orcs.

We don’t want things to get too confusing. Real-life ORCs might be a little too different from your typical fantasy  creature to make for good merch. But you know what does?

Real-life unicorns! Over at DFTBA.com/SciShow, you  can get this adorable sticker set celebrating the one-horned  animals of our actual world. We’ve even made those horns into rainbows, because who wouldn’t want one of those? [♪ OUTRO]