Not 404. Image: Departure shot of Pluto by NASA's New Horizons spacecraft, showing Pluto's atmosphere backlit by the Sun. The blue color is close to what a human eye would have seen, and is caused by layers of haze in the atmosphere, similar to those observed at Saturn’s moon Titan. Credit: NASA/JHUAPL/SwRI, Wikimedia Commons. Page last updated: 2020-12-16 11:49:50 UTC