It’s been nine months since NASA’s New Horizons spacecraft flew past Pluto. Time sure does fly. And even though the spacecraft is moving further from Pluto and Earth, it’s still sending back the massive amounts of data it gathered during closest approach. As this data is received, the huge team of scientists that are part of the mission use it to characterize Pluto so humanity can begin to understand just how strange the distant dwarf Planet is.
Five new papers characterize some of the latest science done on the enigmatic world. Here’s a quick summary of each:
The first paper from Jeffrey Moore et al. discusses the geological features across Pluto and it’s largest moon, Charon. There is a great contrast between the two worlds, with Charon being geologically dead, ancient, and cratered. Pluto on the other hand has evidence of plate tectonics, glaciers, cryovolcanoes, and ice deposits. Varying terrain suggests Pluto is very active geologically, meaning processes have been occurring to shape it’s terrain as recent as a few hundred million years.
The second paper, from Will Grundy et al. characterizes the composition of the surfaces of Pluto and Charon. Most of the surface is dominated by ices that include water ice and solid nitrogen, varying over seasonal changes and longer geological timescales. In some enhanced-colour photos, Pluto has a reddish-brown hue, the result of molecules called Tholins that have accumulated.
The third study by G. Gladstone et al. characterizes the surprising atmosphere of Pluto. Mostly composed of Methane, it is cold and compact, with many distinct layers of haze that are easily seen in photos from New Horizons.
In the fourth study, Harold Weaver et al. report on the smaller moons Nix, Hydra, Kerberos, and Styx, which are small, bright, and rotate quickly. In the image below you can see how quickly the moons are rotating. They will eventually become tidally locked as Pluto’s gravity slows them down, but it will take a long time.
Finally, Fran Bagenal et al. shows how Pluto modifies it’s environment in space through interactions with solar wind. It also has very little dust in the surrounding environment, which could mean it has been swept up over time, or there have been few impacts in recent times.
Either way, the new results show a full workup of the Pluto system that is ongoing and fascinating. As we learn more of the distant dwarf planet, we can piece together it’s history, which infers the entire history of the outer solar system.