The Galaxies We Failed To Count

If you’ve ever looked up at the night sky and felt dwarfed by the magnitude of the universe, prepare to feel even more insignificant. When astronomers analyzed deep space images gathered by NASA’s Hubble Telescope in the mid-1990s, they estimated that the observable universe contained about 200 billion galaxies. It turns out they were off by a bit. Well, more than a bit. New models reveal that the previous estimate is at least 10 times too low. There are closer to 2 trillion galaxies in the universe. So, what does this mean? How do scientists know this information? And, why, with 10 times more galaxies, are there still patches of darkness in the night sky? Joel Green, a project scientist in the Office of Public Outreach at the Space Telescope Science Institute, joins us to answer these celestial questions.