Scientists from NASA with the help of the American automatic interplanetary station "New Horizons" (New Horizons) took a photo of the part of Pluto, which does not fall on sunlight. The team of scientists called this part "the dark side of Pluto". For illumination, the team used sunlight reflected from Pluto's moon Charon.
Photo and scientific interpretation published in The Dark Side of Pluto in the Planetary Science Journal.
The station became the first spacecraft in history to explore the Pluto system at close range. Now another interesting photo has been added to this photo album. The bright ring surrounding Pluto is sunlight scattered in the dwarf planet's atmosphere.
The image was compiled from 360 photographs taken by the interplanetary station. Most of Pluto's southern hemisphere at this point was plunged into darkness - similarly, the Sun is not visible in the polar regions of the Earth. True, on Pluto, such dark seasons last for 62 Earth years.
In the animation above, a black circle outlines the dimensions of Pluto. The vertical orange line is the boundaries of the illumination of the dwarf planet by the light reflected from Charon. Dotted lines represent latitudes. Pluto's South Pole is in the photo below. The large bright area of the surface located between the pole and the equator is most likely represented by deposits of nitrogen or methane ice.
"New Horizons" flew past Pluto at a distance of 12,550 km from it in July 2015, and went further, at a speed of 14.5 km / s, towards Arrocot, a contact binary trans-Neptunian asteroid from the Kuiper belt. But as it flew away from Pluto, the space station took some goodbye photos of its dark side.
There is a surprising coincidence, according to Tod Lauer, an astronomer at the National Observatory of Optical Astronomy and lead author of the work. The amount of light reflected by Charon towards Pluto almost corresponds to the amount of light reflected by the Moon towards the Earth in each of the phases. At the time of the passage of the station, Charon was in a phase corresponding to the first quarter of the moon phase.
Pulling out image details from such moonlight photos was not easy. The reflected light was dim, and the rays scattered in the atmosphere lit up the picture. John Spencer, planetary scientist and member of the New Horizons team, likened this to trying to see a road sign through a dirty windshield while driving into the sunset without a visor in your car.
Pluto's south pole and the surrounding surface are covered in some kind of dark material that contrasts with the pale surface of the planet's northern hemisphere. Planetary scientists suggest that this difference arose due to the fact that summer in the southern hemisphere of Pluto recently ended (15 years before the station's flight). Nitrogen and methane ice could sublimate, leaving behind darker rocks.
Future observations of Pluto from Earth will be able to confirm or disprove these hypotheses - however, this will have to wait until the southern hemisphere of Pluto is illuminated, which will happen only in 100 years. Lauer said it would be easier to send another mission to Pluto.
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