An artist's impression of Charon as it might appear from the surface of Pluto. In this depiction, Charon's phase is new - i.e. the Sun is directly behind it. Therefore Charon is only visible by the faint sunlight that Pluto reflects onto it from the Sun. Because Pluto and Charon are tidally locked, they keep the same face towards each other at all times, as the Moon does to the Earth. So if one stood on Charon (or Pluto) the other world would stay fixed in the sky - never setting or rising, but still cycling through its phases. And if one were on the wrong hemisphere of Pluto (or Charon) one would never see the other world. The New Horizons probe recently revealed that Pluto has clouds in its atmosphere, as this illustration depicts.