How Many Galaxies Actually Exist? The Number Keeps Changing - Sleepy Science Explainer

For decades, the confident answer was 100 billion galaxies in the observable universe. Then in 2016 that number was revised upward by more than an order of magnitude, to roughly two trillion. And now, new observations from the James Webb Space Telescope are complicating the picture yet again. This video traces the surprisingly recent history of galaxy counting, from Kant's 1755 speculation about "island universes," through the 1920 Great Debate, Edwin Hubble's landmark 1923 distance measurement to Andromeda, and the 1995 Hubble Deep Field image that first revealed thousands of galaxies hiding in a seemingly empty patch of sky — all the way to why the true, final number may not even exist. #Space #Astronomy #Cosmology