Unless I’m seriously mistaken, there were no confirmed planets outside our solar system when I was a kid. We assumed that they were there, but we didn’t know it. Now we do. (Of course, we can — just barely — see only the very biggest of them, which is why the “exoplanets” shown above are all quite large.) This image shows an artist’s impression of ten hot “Jupiter-class” exoplanets. From top left to lower left... Read more