Scientists have spent years digesting New Horizons data from Pluto’s flyby. The spacecraft found vast nitrogen glaciers, methane- and water-ice mountains, an intriguingly complex atmosphere, an age-spanning terrain profile including dunes constructed out of solid methane grains rather than earthen sand dunes, vast nitrogen glaciers and methane glaciers resembling Earthly ones and numerous dunes similar to sand dunes here on Earth.
In addition, this mission unveiled a frozen heart-shaped region on Pluto as well as an intriguing baby comet named Arrokoth.
What is Pluto?
Pluto, located in the outer solar system, is part of the Kuiper belt; an expansive region beyond Neptune that may hold millions of other icy bodies.
Astronomers dethroned Pluto a decade ago, yet since then scientists have continued to find objects similar to it that share many characteristics with it. To distinguish them, scientists had to either add another class of planets — or eliminate Pluto altogether from their roster of planets.
NASA launched New Horizons spacecraft on Jan 6, 2006 with an ambitious plan of visiting Pluto and its moons. After using gravity assist flyby of Jupiter to increase speed, New Horizons reached Pluto on July 14, 2015. It beamed back amazing images and data; one surprising discovery being subsurface ocean. Another find was Tombaugh Regio on Pluto (named for Clyde Tombaugh who discovered it in 1930), covered by carbon monoxide ice that covered much of its surface area.
What is Charon?
James Christy’s discovery of Pluto’s largest moon, Charon, in 1978 marked an important step towards understanding this dwarf planet. Christy took inspiration for its name from Greek mythology–Charon refers to a ferryman who transports souls across River Acheron and Pluto’s realm in the underworld; adding “on” makes the name more scientific sounding (ie “electrons and neutrons”.)
New Horizons images reveal that Charon’s surface is scattered with craters. Additionally, however, New Horizons revealed an informally named Vulcan Planum region which features grooves and faint ridges suggesting wide-scale volcanic activity on this world.
Charon has an intense red hue. Scientists believe this hue derives from nitrogen, methane and carbon monoxide present in its atmosphere reacting with cosmic rays from galaxies surrounding Pluto to form complex organic molecules known as tholins that interact with galactic cosmic rays to form an atmospheric haze which funnels down towards Pluto due to Charon’s close orbit.
What is Sputnik Planitia?
Sputnik Planitia on Pluto stands out as an iconic feature. Scientists are still struggling to explain what caused its intricate polygonal shapes in this nitrogen ice impact basin.
Answers may lie within sublimation, the process by which solid matter transforms to liquid state and back again. Sputnik Planitia seems to be subjected to sublimation as evidenced by pits in its icy landscape; these marks show where convection cells exist where surface ice is heated by sublimating below, leading to upwelling and sinking material resulting in polygonal forms of upwelling and sinking that form the basis of Sputnik Planitia.
James Keane and Isamu Matsuyama from the University of Arizona provide further evidence in support of Nimmo’s theory, publishing their research in Nature together. According to them, Sputnik Planitia’s tidally locked orbit with Charon could be driven away from it due to volatile ices filling its interior causing its center of mass to shift outward, leading to tidal forces dislodging Sputnik Planitia from Charon.
What is Tombaugh Regio?
Nasa’s New Horizons probe captured stunning, high-resolution images of Pluto from space, including an eye-popping heart-shaped region known as Tombaugh Regio – where nitrogen ice warms and turns to vapor during the day, condensing at night into nitrogen winds which sweep across its surface.
Sputnik Planitia lies within a three-kilometer-deep basin known as Sputnik Planitia, with its left “lobe” consisting of an ice sheet covering 1,000 kilometers (622 miles). Meanwhile, its right “lobe” comprises highlands. Together these features are formed through dynamic processes which also shape other parts of this dwarf planet’s complex terrain.
Tanguy Bertrand, a planetary scientist at NASA’s Ames Research Center in California and lead author of a recent study published this week in the American Geophysical Union Journal of Geophysical Research: Planets has used New Horizons images to reveal that Pluto is geologically active and will likely remain so as more data from its historic flyby continues to come back into our planet. Scientists will continue debating what this implies about the dwarf planet’s unique appearance.