An image taken of Pluto from four million kilometers [2.5 million miles] away shows four intriguing dark spots on the far side of the dwarf planet, a part of its surface that always faces its moon, Charon.
The New Horizons spacecraft has taken the best image yet of four mysterious dark spots on Pluto's surface, as it gets closer to the dwarf planet; the picture was described by NASA scientists as "the last, best look that anyone will have of Pluto’s far side for decades to come."
The four spots have now been estimated to measure about 480 kilometers across, and are connected to Pluto's dark equatorial region.
"It’s weird that they’re spaced so regularly," commented a scientist from the New Horizons team. "We can’t tell whether they’re plateaus or plains, or whether they’re brightness variations on a completely smooth surface."
The image was taken on July 11, three days before the spacecraft is due to make its close flyby of Pluto on July 14, when it zooms in at a speed of 49,600 km/h and an altitude of just 12,500 km, collecting data from the first-ever close-up look at the icy dwarf planet.
"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," said Jeff Moore from NASA’s Ames Research Center.
The close flyby will focus on the opposing side of Pluto, providing the first images of its night region, where the Sun has not shone for 20 years, and won't shine again for another 80 years. Its south polar region is instead being illuminated by moonlight from Charon, the largest of Pluto's five moons.