Chron3I/ATLAS comet nears sun-hints at secrets from distant star systemAriana Garcia
Mon, October 27, 2025 at 10:05 PM EDT
3 min read
Images taken from Gemini South in Chile show the growing tail of comet 3I/ATLAS and the glowing coma. ( International Gemini Observatory/NOIRLab/NSF/AURA/Shadow the Scientist Image Processing: J. Miller & M. Rodriguez (International Gemini Observatory/NSF NOIRLab), T.A. Rector (University of Alaska Anchorage/NSF NOIRLab), M. Zamani (NSF NOIRLab))The interstellar comet 3I/ATLAS is now reaching its closest point to the sun, or perihelion, on Wednesday, according to NASA. At just 130 million miles from our star, the comet is expected to flare in brightness as solar radiation heats its surface and blasts streams of gas and dust into space. Astronomers say that when 3I/ATLAS emerges from behind the sun in early November, it could appear much larger and brighter than before.
Earlier this month, the comet passed within 12 miles of Mars, giving NASA's HiRISE camera aboard the Mars Reconnaissance Orbiter a chance to capture its closest photos yet. Those images have not been released because of the ongoing government shutdown, but researchers say they could reveal new details about the comet's jets and surface.
As 3I/ATLAS approached the inner solar system in September, the Nordic Optical Telescope in Spain's Canary Islands recorded a tail forming after earlier images had shown an "anti-tail," a plume that seemed to point toward the sun. Harvard astrophysicist Avi Loeb suggested the unusual behavior could resemble "controlled maneuvering" and proposed the comet might be an alien spacecraft. Most astronomers, however, explain the changes as a natural result of the comet's rotation and the way sunlight interacts with dust and gas.
Interstellar object 3I/ATLAS imaged by the Hubble Space Telescope. Could similar objects be the seeds of new planets around young stars? (NASA/ESA/David Jewitt (UCLA). Image Processing: Joseph DePasquale (STScI))In late August, images from Chile's Gemini South telescope showed 3I/ATLAS surrounded by a glowing haze and a growing tail as sunlight heated its icy surface, causing frozen gases to vaporize.
In mid-August, scientists using the Very Large Telescope (VLT) in Chile detected the chemical signature of cyanogen gas as the comet reached about three astronomical units from the sun. Earlier, on July 20, the VLT team led by Rohan Rahatgaonkar and Darryl Seligman reported glowing nickel vapor in the comet's atmosphere when it was still nearly four times farther from the sun than Earth. The researchers said metals like nickel usually require much higher temperatures to vaporize, making the finding unusual.
They also noted that iron was not detected alongside the nickel, an uncommon pattern in comets. Rahatgaonkar and Seligman suggested that the nickel may be locked in molecules that break apart easily under sunlight, releasing the metal at low temperatures.
Observations from the James Webb Space Telescope (JWST) revealed that the comet's gas cloud, or coma, contains far more carbon dioxide than water, a reversal of the typical ratio seen in solar system comets. JWST also detected water ice and carbon monoxide gas, suggesting a complex mix of frozen materials. According to Rahatgaonkar and Seligman, this composition indicates that 3I/ATLAS likely formed billions of years ago in a very cold region around another star, possibly predating our solar system.
3I/ATLAS was first detected on July 1, 2025, by the Asteroid Terrestrial-Impact Last Alert System (ATLAS) survey. It is only the third confirmed interstellar object to enter our solar system. According to NASA, it is the largest, fastest-moving, and possibly the oldest interstellar visitor observed to date. Scientists continue to monitor its activity as it completes its brief but revealing passage through the solar system, carrying chemical clues from a distant star system.
https://www.yahoo.com/news/articles/3i-atlas-comet-nears-sun-020515228.html
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