Pluto's System: the movements of the bodies in three days

These HST images, taken by the Advanced Camera for Surveys, reveal Pluto, its large moon Charon, and the planet's two new candidate satellites. Between May 15 and May 18, 2005, Charon, and the putative moons, provisionally designated P1 and P2, all appear to rotate counterclockwise around Pluto. P1 and P2 move less than Charon because they are farther from Pluto and therefore would be orbiting at slower speeds. P1 and P2 are thousands of times less bright than Pluto and Charon. The enhanced-color images of Pluto (the brightest object) and Charon (to the right of Pluto) were constructed by combining short exposure images taken in filters near 475 nnmts (blue) and 555 nnmts (green-yellow). The image of the new moons were made from longer exposures taken in a single filter centered near 606 nnmts (yellow) and therefore no color information is available for them.