CaliToday (28/8/2025): Astronomers have detected a chemical anomaly in the first images of the interstellar comet 3I/ATLAS captured by the James Webb Space Telescope as it hurtles toward the sun. These initial observations reveal that 3I/ATLAS has an exceptionally high ratio of carbon dioxide (CO2) to water (H2O), a composition that, if confirmed, could shed light on its formation in a distant, unknown star system.
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| Researchers used NASA's James Webb Space Telescope to observe 3I/ATLAS on Aug. 6. | Credit: NASA/James Webb Space Telescope |
A Rare Interstellar Visitor Under Scrutiny
Since its discovery in July, scientists have been racing to study 3I/ATLAS, only the third confirmed interstellar object ever detected. Researchers are eager to analyze its composition before the rare visitor slingshots around the sun in October and vanishes from our solar system forever.
On August 6, researchers used JWST's Near-Infrared Spectrograph to analyze the light emitted from the comet, decoding its physical properties. The findings, reported in a pre-print paper, indicate that the comet's atmosphere, or coma, is unusually rich in carbon dioxide. A coma forms as a comet approaches a star, causing its ice and other materials to heat up and release gas in a process called outgassing. The JWST data suggests that the gas cloud surrounding 3I/ATLAS is predominantly CO2.
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| NASA's Hubble Space Telescope captured an image of 3I/ATLAS on July 21. | Credit: Image: NASA, ESA, David Jewitt (UCLA); Image Processing: Joseph DePasquale (STScI) |
Clues to a Distant Birthplace
Researchers theorize this high CO2 content could be linked to two possibilities concerning its origin:
High Radiation Exposure: The comet may be composed of ice blocks that were exposed to significantly higher levels of radiation than comets in our own solar system.
Formation Location: It might have formed near the "CO2 snowline" of its parent protoplanetary disk—the region around a young star where CO2 freezes into solid ice.
"Our observations are consistent with a CO2-rich nucleus," the researchers wrote, suggesting a unique formation environment compared to our solar system's comets.
A Comet of Superlatives
Everything about 3I/ATLAS seems to break records. It is currently traveling at over 130,000 mph (210,000 km/h) on a highly unusual, flat trajectory. With a diameter estimated to be around 3.5 miles (5.6 km), it is likely the largest interstellar object ever seen. One study even suggests it could be the oldest, possibly predating our own 4.6-billion-year-old solar system by about 3 billion years.
Despite its unique characteristics, wilder speculations, such as a controversial paper suggesting it could be disguised alien technology, have been firmly dismissed by the scientific community as "nonsense." NASA scientists assert that the comet's record-breaking speed is evidence of a billions-of-years-long journey, propelled by gravitational slingshots past countless stars.
"Nobody knows where the comet came from," said David Jewitt, a UCLA astronomer leading the Hubble observations. "It’s like getting a brief glimpse of a rifle bullet in a microsecond. You can’t back-project with any accuracy to determine the starting point of the trajectory."
