Dwarf planet Pluto emits X-ray, observations using NASA's Chandra X-ray Observatory suggest. The telescope was designed to detect X-ray emissions from very hot regions of the universe.
The findings may shed new light on the space environment surrounding the icy world located about 3.6 billion miles away from the sun.
Astrophysicist Carey Lisse, from the Johns Hopkins University Applied Physics Laboratory (APL) and lead of the Chandra observation team said that it is the first time X-rays were detected from an object in the Kuiper Belt, the region beyond Neptune that scientists believe contain many asteroids, comets and other small bodies composed largely of ice.
Prior to the observations, astronomers believe it is highly unlikely to detect X-rays from Pluto. Astronomers thought that the extraterrestrial world was just a little nugget made of rock and ice but data from New Horizons spacecraft, which visited Pluto in July 2015, revealed signs of an atmosphere.
The presence of the atmosphere prompted researchers to conduct an investigation to know if Pluto is visible in the X-rays part of the spectrum despite that most astronomers think the dwarf planet is located too far from the sun to produce a detectable X-ray glow.
Between February 2014 and August 2015, the researchers pointed Chandra X-Ray telescope at Pluto four separate times and detected low-energy X-rays from the dwarf planet.
"Before our observations, scientists thought it was highly unlikely that we'd detect X-rays from Pluto, causing a strong debate as to whether Chandra should observe it at all," said Scott Wolk, from Harvard-Smithsonian Center for Astrophysics in Cambridge who is part of the team that conducted the study published in the journal Icarus.
"Prior to Pluto, the most distant solar system body with detected X-ray emission was Saturn's rings and disk."
Nonetheless, the X-rays emitted by the icy world baffled scientists because being rocky, cold and without magnetic field, Pluto lacks natural mechanism to emit X-rays. X-rays from the sun could be scattered as they bump into Pluto's atmosphere but the X-ray photons that the researchers measured did not appear like solar at all.
The researchers though posit that high energy particles from solar wind strip away electrons in Pluto's exosphere, the outermost region of the atmosphere, that emits X-rays in the process.
Based on the findings, the researchers said it is probable that other large Kuiper Belt Objects are doing the same.