James Webb telescope discovers carbon dioxide, hydrogen peroxide on Pluto’s moon Cheron; sheds new light on solar system's origin

The James Webb Space Telescope recently made a groundbreaking discovery, detecting solid carbon dioxide and hydrogen peroxide on the frozen surface of Charon, Pluto's largest moon.  

This marks the first time when carbon dioxide is observed on Charon, a spherical body approximately 750 miles in diameter. This finding is particularly remarkable because Charon is the largest moon relative in size to the planet it orbits in our solar system.  

Additionally, the presence of these compounds could provide valuable insights into the enigmatic icy worlds that exist in the outer reaches of our Solar System. 

Webb for the first time detected carbon dioxide and hydrogen peroxide - both frozen as solids - on the surface of Charon, a spherical body about 750 miles (1,200 km) in diameter.   

The discovery of CO2, along with another chemical hydrogen peroxide (H2O2), could shed light on the icy worlds in the mysterious outer reaches of our solar system.   

Charon, discovered in 1978, has the distinction of being the solar system's largest moon relative in size to the planet it orbits. It is about half the diameter and an eighth the mass of Pluto.  

Pluto, which was earlier known as the ninth planet of the solar system was downgraded to dwarf planet in 2006 after other similar objects were spotted in a region beyond Neptune called the Kuiper Belt.  

The doughnut-shaped Kuiper Belt is thought to be home to millions of icy worlds.  

Charon offers a rare glimpse into these worlds because -- unlike other Kuiper Belt objects, including Pluto -- its surface is not obscured by highly volatile ices such as methane, Silvia Protopapa of the Southwest Research Institute in the US state of Colorado told AFP.  

The distance between Charon and Pluto is about 19,640 km compared to 384,400 km on average separating Earth from its moon.  

Charon’s surface is mostly grey with reddish-brown regions around its poles composed of organic materials. NASA’s New Horizon spacecraft flew past Charon in 2015 and discovered the surface was mainly covered in water ice and ammonia, which are thought to give the moon its red and grey appearance.  

The study tapped into the ability of Webb, which was launched in 2021 and began collecting data the following year, to observe across a greater range of wavelengths than previously available.  

Researchers said the carbon dioxide observed by Webb was probably buried underneath the surface and exposed by impacts on Charon. The carbon dioxide, they said, is likely to have been part of the primordial material from which both Charon and Pluto originally formed.  

Scientists were surprised that carbon dioxide was not previously spotted.  

“The detection of carbon dioxide was a satisfying confirmation of our expectations,” said Protopapa, assistant director of the department of space studies at the Southwest Research Institute in Boulder, Colorado, co-investigator of the New Horizons mission and lead author of the study published in the journal Nature Communications, opens new tab.  

The new observations of Charon help tell a broader story about the celestial bodies populating our solar system.  

“Every small body in the outer solar system is a unique piece of a larger puzzle that scientists are trying to assemble,” Protopapa said.  

The researchers used a Webb instrument called the Near-Infrared Spectrograph to make four observations in 2022 and 2023, getting full coverage of Charon’s northern hemisphere, according to a Reuters report.  

The presence of hydrogen peroxide, sometimes used as a disinfectant on Earth, suggests Charon's icy surface is altered by ultra-violet light and solar wind from the distant Sun, according to the study.  

Discovering and disentangling these chemicals on Charon is another “piece of the puzzle” in the quest to uncover more about these distant worlds -- and in turn the birth of our Solar System, Protopapa said.  

(With input from agencies)