Scientists have long reckoned that the first galaxies came into being roughly 500 million to 1 billion years after the Big Bang, but finding these ancient celestial bodies is tricky when their light is so faint that even many specialized tools aren't up to the job. However, researchers have managed to spot a galaxy so old that it's making them question the established timeline for the universe. They've determined that the recently discovered EGS8p7 galaxy is a whopping 13.2 billion years old, making it both the farthest known galaxy to date and just 600 million years younger than the universe as we know it. Theoretically, it shouldn't be possible to see the galaxy at all -- in EGS8p7's era, space was supposed to be full of neutral hydrogen clouds that absorbed radiation and made galaxies invisible to later observers.
The discoverers have some theories for why they found this extremely distant star hub. The hydrogen reionization in its era may have been patchy, making it feasible to spot some galaxies but not others. Also, EGS8p7 may have been populated by exceptionally hot stars that created a giant hydrogen bubble and broadcast the galaxy's presence. Whatever factors led to this rare sighting, it's clear that humanity's understanding of the oldest galaxies still needs some fine-tuning.
[Image credits: NASA/ESA/R. Ellis (Caltech)/HUDF 2012 Team, Flickr (top); I. Labbé (Leiden University)/NASA/ESA/JPL-Caltech (bottom)]