Dwarf planet Pluto and its principal moon Charon seen from the LORRI telescope of NASA space probe New Horizons. ©NASA
14 July 2015 — As it sped by the last planet of the Solar System at 56,000 km/h, New Horizons has obtained impressive new images of Pluto and its large moon Charon that highlight their compositional diversity. These are not actual color images of Pluto and Charon—they are shown here in exaggerated colors that make it easy to note the differences in surface material and features on each planetary body.
The images were obtained using three of the color filters of the “Ralph” instrument on 13 July at 3:38 am EDT. New Horizons has seven science instruments on board the spacecraft. “These images show that Pluto and Charon are truly complex worlds” said New Horizons co-investigator Will Grundy, Lowell Observatory, Flagstaff, Arizona. “Our surface composition team is working as fast as we can to identify the substances in different regions on Pluto and unravel the processes that put them where they are.”
The color data helps scientists understand the molecular make-up of ices on the surfaces of Pluto and Charon, as well as the age of geologic features such as craters. They can also tell us about surface changes caused by space “weather,” such as radiation.
The new color images reveal that the “heart” of Pluto actually consists of two remarkably different-colored regions. In the false-color image, the heart consists of a western lobe shaped like an ice cream cone that appears peach color in this image. A mottled area on the right (east) side looks bluish. A mid-latitude band appears in shades ranging from pale blue through red. Even within the northern polar cap, in the upper part of the image, various shades of yellow-orange indicate subtle compositional differences.
Siding Pluto, the surface of its big moon Charon is viewed using the same exaggerated color. The red on the dark northern polar cap of Charon is attributed to hydrocarbon and other molecules, a class of chemical compounds called tholins. The mottled colors at lower latitudes point to the diversity of terrains on Charon. “We make these color images to highlight the variety of surface environments present in the Pluto system,” said Dennis Reuter, co-investigator with the New Horizons Composition Team. “They show us in an intuitive way that there is much still to learn from the data coming down.”
Due to the three-billion-mile distance to Pluto, data takes 4 ½ hours to come to Earth, even at the speed of light. It will take 16 months for all of New Horizons’ science data to be received, and the treasure trove from this mission will be studied for decades to come.
By Tricia Talbert