Interstellar Comet 3I/ATLAS Glows Green During Lunar Eclipse
On September 7, 2025, a total lunar eclipse cast a shadow over the moon, providing a remarkable backdrop for amateur astronomers in Namibia. Michael Jäger and Gerald Rhemann seized this opportunity to capture stunning images of the interstellar comet 3I/ATLAS, revealing an unexpected green glow. This phenomenon has piqued the interest of astronomers worldwide.
The lunar eclipse, which turned the moon a striking blood red, allowed Jäger and Rhemann to photograph 3I/ATLAS against some of the darkest skies on Earth. Their findings suggest that the comet’s green hue may be attributed to the presence of diatomic carbon (C2), a molecule known for fluorescing when exposed to sunlight. This is a significant observation, as it marks the first time 3I/ATLAS has shown this distinctive coloration.
Understanding 3I/ATLAS
3I/ATLAS is only the third confirmed interstellar comet to be observed passing through our solar system. Its hyperbolic trajectory indicates that it is not gravitationally bound to the sun and likely originates from another star system. This adds to the intrigue surrounding its chemical makeup and origin.
Previous interstellar objects, such as ‘Oumuamua and 2I/Borisov, have also sparked discussions about their nature. While 2I/Borisov exhibited a more typical dusty coma and tail, 3I/ATLAS offers a unique chance to investigate material formed around a different stellar environment.
The photograph taken in the Kalahari Desert highlights the comet’s unusual characteristics that astronomers are eager to examine. Despite previous findings from the Kitt Peak Observatory in Arizona, which indicated that 3I/ATLAS is low in carbon-chain molecules, the recent observations raise questions. If diatomic carbon was indeed absent just weeks prior, what has changed?
Investigating the Green Glow
Several theories may explain the comet’s newfound green color. One possibility is that the sun’s heat melted layers of ice on the comet’s surface, releasing trapped diatomic carbon molecules. Alternatively, the green glow could arise from other unknown molecules that fluoresce under sunlight. Given its interstellar nature, 3I/ATLAS might possess chemical compositions not typically found in solar system comets.
As astronomers continue to study 3I/ATLAS, it remains shrouded in mystery. The comet’s journey through our solar system is an exciting opportunity for researchers to deepen their understanding of celestial bodies from beyond our own star system.
For those interested in the ongoing exploration of 3I/ATLAS, further details about its imaging and trajectory toward the sun will be available as studies progress. The discoveries surrounding this interstellar visitor could reshape our understanding of comets and the materials that form them.
