Astronomers monitoring the sky recently received a major surprise. They discovered a massive galaxy around our own in an area previously unexplored. It popped up, apparently, out of nowhere.
So how could the galaxy, dubbed as Crater 2, accomplish this feat, much like a deer bursting from intergalactic bushes to look us down through our collective headlights? While the emergence may look abrupt, Crater 2 has been around the whole time. We just overlooked it.
However, given that we know it exists, there are a few additional embarrassing aspects found by astronomers. To begin, we cannot blame the galaxy's relative obscurity on its vastness. Crater 2 is so massive that it has already been classified as the fourth biggest galaxy circling our own. We cannot also blame its remoteness. Crater 2's orbit around the Milky Way places it directly above.
With that stated, how did we manage to miss it? Researchers at the University of Cambridge have an answer for us in a recent publication published in Monthly Notices of the Royal Astronomical Society. Despite its size and proximity, Crater 2 is likewise a rather dark galaxy. Indeed, it is one of the faintest galaxies ever discovered. This, together with several considerably brighter neighbors, allowed the galaxy dubbed "the feeble giant" to remain undetected until today.
However, now that we have seen Crater 2, the finding raises concerns about what more may exist. Researchers are already discussing the possibility of conducting a search for such huge, dark galaxies in our neighborhood. It serves as an excellent reminder that there is still a great deal about space that we do not understand.
Reference(s): Peer-Reviewed Research Paper