Astronomers scanning the skies just got a huge surprise. They discovered a gigantic galaxy orbiting our own, where none had been seen before. It just came out of nowhere. So, just how did the recently-discovered Crater 2 succeed to pull off this feat, like a deer jumping out from the interstellar bushes to suddenly shock us? Even though the appearance may seem sudden, the Crater 2 has been there all along. We just never saw it.
Milky Way, Image Credit: ESO / Serge Brunier, Frederic Tapissier via NASA
Now that astronomer know it’s there, though, there are a few other crushing facts that astronomers discovered. First of all, we can’t blame the galaxy’s size for its relative insignificance. Crater 2 is so massive that researchers have already identified it as the fourth largest galaxy orbiting our own. We can’t even blame its distance, either. Crater 2's orbit around the Milky Way puts it just precisely in our neighborhood.
That being said, the question arises, how did we still not know it was there? A new research paper published in Monthly Notices of the Royal Astronomical Society from astronomers at the University of Cambridge has an answer for us. It turns out that, regardless of being huge and close, Crater 2 is also a pretty dark galaxy. Actually, it’s one of the faintest galaxies ever detected in the cosmos. That, along with some much perkier neighbors, let the galaxy that astronomers have nicknamed “the feeble giant” remain hidden from our eyes until now.
Now that we have observed Crater 2, nevertheless, the discovery yields some questions about what else could be out there that we are still missing. Astronomers are already talking about starting a hunt for similarly large, dark galaxies near us. It’s a good thing that there’s still so much about cosmos that we still don’t know.