Chandrayaan-2's lunar orbiter has made a groundbreaking observation by detecting the effects of a Coronal Mass Ejection (CME) from the Sun on the Moon. This significant event occurred on May 10, 2024, when the orbiter's instrument, Chandra’s Atmospheric Composition Explorer-2 (CHACE-2), recorded an increase in the total pressure of the Moon's fragile atmosphere, known as the exosphere, during the CME impact.

The observations revealed that the number density of neutral atoms and molecules in the lunar exosphere increased by more than ten times, aligning with previous theoretical predictions. This marks the first time such an effect has been directly observed by CHACE-2, according to an official statement.

The Moon's exosphere is a thin layer of gas formed by solar radiation, solar wind, and meteorite impacts. It is categorized as a surface boundary exosphere, meaning the gas atoms and molecules present rarely interact. The exosphere is sensitive to changes in solar activity, particularly during CMEs, which are events where the Sun ejects large amounts of its material, primarily Helium and Hydrogen ions.

The recent CME event provided a unique opportunity to study how solar emissions affect the Moon's environment. The increased solar coronal mass led to a greater release of atoms from the lunar surface, contributing to the observed rise in pressure within the sunlit exosphere.

These findings enhance our understanding of the Moon's atmosphere and the impact of space weather on it. They also highlight the challenges for future lunar missions, as any scientific bases on the Moon will need to consider the effects of such extreme solar events on the lunar environment.