Scientists have only just started finding extremely faint galaxies. However, they've already topped themselves by discovering the faintest known galaxy to date... and it might just provide insight into the universe's early days. Found through gravitational lensing, the galaxy is both supremely ancient (13 billion years old) and extremely tiny (just 0.0001 percent the size of the Milky Way). In other words, it's a textbook example of the dwarf galaxies that researchers believe were key to re-ionizing the universe and taking it out of the lightless "dark ages." With enough study, it could help explain what triggered that ionization and fill in one of the gaps in our understanding of existence.