Planetary researchers have long thought that the dwarf planet Ceres may have a temporary, thin atmosphere (an exosphere), but mysteries lingered about its origin and why it’s not always present. Now, scientists from NASA’s Dawn mission suggest that the Cerean exosphere appears to be related to the behavior of the Sun, rather than Ceres’ proximity to the Sun.
When energetic particles from the Sun hit exposed ice and ice near Ceres’ surface, it transfers energy to the water molecules as they collide. According to the Dawn team, this frees the water molecules from the ground, allowing them to escape and create a thin atmosphere that may last for a week or so.
“Our results also have implications for other airless, water-rich bodies of the Solar System, including the polar regions of the Moon and some asteroids. Atmospheric releases might be expected from their surfaces, too, when solar activity erupts,” said Dawn mission principal investigator Dr. Chris Russell, from the University of California, Los Angeles.
Before Dawn arrived in orbit at Ceres in 2015, evidence for an atmosphere had been detected by some observatories at certain times, but not others, suggesting that it is a transient phenomenon.
