Hubble Color Images of Pluto’s Moons Support a Common Birth

These NASA Hubble Space Telescope images of Pluto were taken on March 2, 2006, using the High Resolution Channel (HRC) of the Advanced Camera for Surveys (ACS). The image on the left was taken through a blue filter (F435W), and the one on the right was taken through a red filter (F606W). By comparing these two images in detail, astronomers discovered that the surfaces of Pluto's two newly-discovered satellites (S/2005 P 1 and S/2005 P 2, or P1 and P2 for short) have essentially the same color as Charon's surface. All three satellites have surfaces that reflect sunlight with equal efficiency at all wavelengths, which means they have the same color as Earth's moon (in the absence of Earth's atmospheric effects which can alter the apparent color of our moon). In contrast, Pluto's surface has a reddish hue. The remarkable similarity in the colors of the satellites supports the idea that they were all created from material stripped from the surface layers of Pluto during the giant impact that created the entire system more than 4 billion years ago. (Note that the color schemes used to display the images are not meant to represent the colors of the objects. Rather, a blue intensity scale is used for the image taken through the F435W filter and a red intensity scale is used for the F606W image simply to highlight that the images were obtained through two different filters.)