Over 60 billion habitable worlds in our galaxy
That’s a new estimate from astronomers, who have calculated that 40% of red dwarf stars (the most common type of star in our galaxy) “have a so-called ‘super-Earth’ planet orbiting in a habitable zone that would allow water to flow on the surface.” More details here…
Billions of habitable worlds in Milky Way
And that’s just our galaxy. How many galaxies in the universe? Scientists count the number of galaxies in one part of the universe, for example by looking though the Hubble telescope, and then use this as an average for the rest. Most estimates seem to be between 100 and 200 billion galaxies.
How Many Galaxies in the Universe
There may not be 60 billion habitable worlds in every galaxy. But there are a lot of habitable worlds out there. Even if sentient life evolves rarely that still might mean there are a lot of aliens. On the other hand, if there are a lot of aliens out there why haven’t any of them visited us yet? It could be that they are just so far away it’s impossible to get here.
Our best bet at finding sentient life is by listening for their radio signals, which is where SETI (Search for Extraterrestrial Intelligence) comes in. The SETI Institute does a variety of things these days, but the search for extraterrestrial intelligence is funded entirely by private donations.