M57, the Ring Nebula: 2150 Light Years
Circa 150 BC, Greek astronomer and mathematician Hipparchus invented the astrolabe, compiled the first star catalogue, and first determined the distance to the moon. The Hipparcos satellite is named after him.
M57 is not a naked-eye object, so no one alive in 150 BC would have been able to see it. But it was there, tossing off the photons you see today.