We grew up thinking about people living on other planets, thanks to the likes of Superman and Star Wars.
But planets outside of our solar system (and outside science fiction) were really just a theory until the 1990s. That's when telescopes and other detectors improved enough to find the first true "exoplanets."
Now we know of thousands of them, and an overview is provided in . Physicist James Trefil is co-author with astronomer Michael Summers; Dr. Trefil joins us.
