The 350 images from NASA were snapped between 2002 and 2003 by the Hubble Space Telescope. "This has taken four years and 20 computers operating continuously and simultaneously to accomplish," said project leader Marc Buie, who developed special algorithms to sharpen the Hubble data.
One surprising find from the new close-ups: Pluto is changing color, becoming redder and brighter over the span of just two years. How come? Buie admitted to the Los Angeles Times that the cause "is still a mystery to be worked out." (He elaborates more on the implications in his paper on the subject for The Astronomical Journal.)
According to NASA, Pluto's appearance is subject to seasonal changes, but "the overall color is believed to be a result of ultraviolet radiation from the distant sun breaking up methane that is present on Pluto's surface, leaving behind a dark, molasses-colored, carbon-rich residue."
The interplanetary photo shoot was actually undertaken to pave the way for an upcoming closer look at Pluto's surface by a robotic spacecraft. In 2006, NASA launched the New Horizons with precious cargo: the ashes of Pluto's discoverer, Clyde Tombaugh. Currently just near Uranus, the probe isn't expected to reach Pluto until 2015. Interestingly, some of the team members on that project are adamant that Pluto still be categorized as the last of the nine planets.
