HOW FAR CAN you see? On a clear day, the song goes, you can see forever. On a dark night, maybe you can’t see your hand in front of your face. If you’re sharp-eyed, you might glimpse the Great Galaxy in Andromeda—only 2,200,000 light-years away; or the Spiral in Triangulum, a bit farther. Beyond that, we need help.
As early as the thirteenth century, astronomers experimented with glass lenses to make distant objects look closer. The first telescope, according to many historians, was invented in 1608 by a Dutch optician, Hans Lippershey. The following year, inspired by Lippershey, the Italian astronomer Galileo began putting together his own telescopes. With them, he saw the rings of Saturn, some satellites of Jupiter, and the craters of the moon. In England, Sir Isaac…