A collection of high-resolution images of the dwarf planet Pluto and its moon Charon, taken by the New Horizons space probe during its historic flyby in July, have finally arrived, and were released by NASA Thursday. The latest images show the oldest, most heavily cratered terrain -- informally named the Cthulhu Region -- seen on Pluto next to the youngest, most crater-free icy plains.

“If an artist had painted this Pluto before our flyby, I probably would have called it over the top -- but that’s what is actually there,” New Horizons Principal Investigator Alan Stern said, in a statement accompanying the photos. “Pluto is showing us a diversity of landforms and complexity of processes that rival anything we’ve seen in the solar system.”

pluto_sept11(1) Mosaic of high-resolution images of Pluto, sent back from NASA’s New Horizons spacecraft from Sept. 5 to 7, 2015. The image is dominated by the informally-named icy plain Sputnik Planum, the smooth, bright region across the center. This image also features a tremendous variety of other landscapes surrounding Sputnik. The smallest visible features are 0.5 miles (0.8 kilometers) in size, and the mosaic covers a region roughly 1,000 miles (1600 kilometers) wide. The image was taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). Photo: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

According to Jeff Moore, leader of the New Horizons Geology, Geophysics and Imaging (GGI) team at NASA’s Ames Research Center in Moffett Field, California, Pluto’s surface seems to be every bit as complex as that of Mars.

“The randomly jumbled mountains might be huge blocks of hard water ice floating within a vast, denser, softer deposit of frozen nitrogen within the region informally named Sputnik Planum,” Moore said, in the statement.

pluto_sept11(2) This 220-mile (350-kilometer) wide view of Pluto from NASA’s New Horizons spacecraft illustrates the incredible diversity of surface reflectivities and geological landforms on the dwarf planet. The image includes dark, ancient heavily cratered terrain; bright, smooth geologically young terrain; assembled masses of mountains; and an enigmatic field of dark, aligned ridges that resemble dunes; its origin is under debate. The smallest visible features are 0.5 miles (0.8 kilometers) in size. This image was taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). Photo: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Scientists now believe that there might even be a field of dark wind-blown dunes -- a surprising finding that would go against the current estimate of how thick the dwarf planet’s atmosphere is. “Seeing dunes on Pluto -- if that is what they are -- would be completely wild. ... Either Pluto had a thicker atmosphere in the past, or some process we haven’t figured out is at work. It’s a head-scratcher,” William B. McKinnon, a GGI deputy lead from Washington University, St. Louis, said, in the statement.

pluto sept11(3) Two different versions of an image of Pluto’s haze layers, taken by New Horizons as it looked back at Pluto's dark side nearly 16 hours after close approach, from a distance of 480,000 miles (770,000 kilometers), at a phase angle of 166 degrees. Pluto's north is at the top, and the sun illuminates Pluto from the upper right. These images are much higher quality than the digitally compressed images of Pluto’s haze downlinked and released shortly after the July 14 encounter, and allow many new details to be seen. The left version has had only minor processing, while the right version has been specially processed to reveal a large number of discrete haze layers in the atmosphere. In the left version, faint surface details on the narrow sunlit crescent are seen through the haze in the upper right of Pluto’s disk, and subtle parallel streaks in the haze may be crepuscular rays- shadows cast on the haze by topography such as mountain ranges on Pluto, similar to the rays sometimes seen in the sky after the sun sets behind mountains on Earth. Photo: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

New Horizons began its year-long download of new images and other data over the Labor Day weekend. In the coming weeks and months, NASA is also expected to release better images of Pluto’s moons -- Charon, Nix and Hydra.

New Horizons completed the Pluto flyby -- its primary mission -- at 7:49 a.m. EDT on July 14, after nearly a decade-long journey through the solar system that took it more than 3 billion miles from Earth. The spacecraft, which is currently more than 43 million miles beyond Pluto, is now heading to the Kuiper Belt -- a region of the outer Solar System made up of objects left over from its infancy.