On January 1 the New Horizons probe whizzed past Ultima Thule, a tiny world on the fringe of the solar system. Data is still streaming back to Earth, and now the latest image shows the object closer and in higher resolution than ever before. With that improved clarity comes some intriguing new landmarks on the rocky surface.

This image was snapped from a distance of 4,200 mi (6,700 km) from the object – much closer than the 17,000 mi (27,000 km) of the previous batch of images. It was taken by New Horizons' wide-angle Multicolor Visible Imaging camera (MVIC) with an original resolution of 440 ft (135 m) per pixel, before the science team sharpened the image.

This closer look reveals a few new details about Ultima Thule. It's quite a lumpy-looking world, dotted with small pits measuring up to 0.4 mi (0.7 km) wide. Then there's a particularly big one on the smaller of the two lobes – which the team has nicknamed "Thule" – that stretches 4 mi (7 km) wide. The team isn't sure whether these pockmarks were made by impacts with smaller objects, if they're collapse pits, or the result of volatile materials escaping into space from below the surface.

Another interesting feature is the brighter marks, which the team can't explain yet. The most obvious example is the "collar" that forms the seam between the two lobes of the object.

Although this particular image was shot just 23 minutes after the previous batch we saw, it's taken an extra three weeks to get to Earth. That's because the Sun passed between us and New Horizons shortly after, so the spacecraft was instructed to hold off the transmission until we had a clear link again. This image finally arrived on January 18 and 19, and although it's the clearest so far, it won't be for long.

"This new image is starting to reveal differences in the geologic character of the two lobes of Ultima Thule, and is presenting us with new mysteries as well," says Alan Stern, Principal Investigator of the New Horizons team. "Over the next month there will be better color and better resolution images that we hope will help unravel the many mysteries of Ultima Thule."

Source: Johns Hopkins Applied Physics Laboratory