The instrument that magnifies the distant — gathering and focusing light, first through lenses, then giant mirrors, and now across invisible wavelengths and from orbit — to make faraway things appear near and to collect light too faint for the eye. Invented in the Netherlands around 1608 and first turned to systematic, published use on the sky by Galileo from 1609, it dethroned the Earth from the center of creation and has been enlarging the known universe ever since.
It is just a tube of glass, yet it moved the Earth. When Galileo pointed one at the sky in 1609 and saw moons circling Jupiter, he proved that not everything turns around us. The tube has been growing ever since — lenses gave way to giant mirrors, then to instruments in orbit. With each one, the universe got larger and our place in it got smaller.