Charon Viewed from Telescope

Astronomer James Christy discovered Charon in 1978 with an Earth-based telescope. He noticed what looked like a change in Pluto’s shape that cycled every 6.4 days. He was actually seeing Charon, which is so close to Pluto that it makes a single orbit in that short time. Each also rotates on its axis every 6.4 days, so Charon always shows the same face to Pluto and never rises or sets.