It looks as if astronomers have been way, way off on their galaxy counts: A new analysis of data from the Hubble Space Telescope suggests that the observable universe holds at least 2 trillion galaxies, which is 10 times the previous estimate.
How could scientists be so far off? The key is that the early universe appears to have had lots of relatively small, faint galaxies. As they merged to form larger galaxies, the population density dwindled.
It took Hubble’s deep-field surveys to register the smaller galaxies that existed far back in time, and it took painstaking analysis to count up a sampling of those galaxies.