New Horizons gets the last and best look at Pluto’s far side

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With just two days to go before New Horizons’ closest flyby of Pluto, the spacecraft has sent across the best pictures of the dwarf planet’s far side i.e. the Charon—facing side that will be invisible to New Horizons when the spacecraft makes its close flyby the morning of July 14.

The Charon-facing side features four dark spots connected to a dark belt like structure circling Pluto’s equatorial region. The evenly-spaced nature of these four spots has left scientists baffled and they aren’t able to tell whether these are plateaus or plains or mere brightness variations on a completely smooth surface.

New Horizons principal investigator Alan Stern of the Southwest Research Institute, Boulder, Colorado, describes this image as “the last, best look that anyone will have of Pluto’s far side for decades to come.”

According to estimates, these large dark areas are about 300 miles (480 kilometers) across and the latest image reveals that the dark areas are more complex than they initially appeared, while the boundaries between the dark and bright terrains are irregular and sharply defined.

In addition to solving the mystery of the spots, the New Horizons Geology, Geophysics and Imaging team is interested in identifying other surface features such as impact craters, formed when smaller objects struck the dwarf planet.

Jeff Moore of NASA’s Ames Research Center, Mountain View, California notes, “When we combine images like this of the far side with composition and color data the spacecraft has already acquired but not yet sent to Earth, we expect to be able to read the history of this face of Pluto.”

When New New Horizons makes its closest approach to Pluto on July 14, it will focus on the opposing or “encounter hemisphere” of the dwarf planet while passing about 7,800 miles (12,500 kilometers) from the face with a large heart-shaped feature that’s captured the imagination of people around the world.