Even though NASA’s New Horizons has flown by Pluto a long time ago – the spacecraft is now more than 186 million miles away from it – it’s still transmitting pictures of the mysterious icy world to the team on Earth.
In the latest images, we can see a field of icy “halos” that are brighter than the rest of the dark surface of Pluto – some craters located in a region that scientists informally call Vega Terra.
The New Horizon team that processes these images interpreted them as “methane ice that lines the crater walls and surrounding ridges, creating halo-like forms.”
Pluto never ceases to amaze us, as the halos are just the latest in a plethora of puzzles scientists are still trying to solve. In a recent press release, NASA said the “bright methane ice on these crater rims and walls are a mystery.”
The most curious fact is that the effect is not visible broadly across Pluto, only in this specific region. NASA has posted a collage of halo images on its official website.
As the New Horizons spacecraft flew by Pluto last summer, it imaged the surface of the blue dwarf planet, sending back peculiar black-and-white images featuring several dozen halos.
The largest halo crater detected by the spacecraft measures almost 30 miles. Thanks to the bright ice against the dark surface, the halos seem to have a certain glow.
In the image featured above, there’s a display of iridescent purple and blue, generated with New Horizons’ Ralph/Linear Etalon Imaging Spectral Array (LEISA). The color purple highlights the distribution of methane ice while the blue – visible between and in the craters – shows the location of water ice.
For now, it’s a complete mystery why the methane ice clings to the walls and ridges of the craters. The bright snow, however, is something scientists are familiar with, having seen it before.
Back in March, some NASA images showed snow-capped mountains against the backdrop of a darker surface region of Pluto.
The bright peaks instantly generated rumors of “snow on Pluto,” but the New Horizon team quickly pointed out that even if there would be snow on Pluto, it would look nothing like the snow humans are used to.
According to New Horizons scientists, the bright snow on Pluto is mostly methane that condensed into ice. John Stansberry, New Horizons science team member, said that “methane ice may act like water in Earth’s atmosphere, condensing as frost at high altitude.”
Image Source: nasa.gov