Surprising new photos of comet 3I/ATLAS taken during last week’s total lunar eclipse hint that the “interstellar visitor” may be turning bright green as it approaches the halfway point on its journey through the solar system.
The resulting photos show 3I/ATLAS with a surprising emerald hue.
The explosive “devil comet” 12P/Pons-Brooks also turned green as it neared the sun in 2024, while astronomers spotted another green comet, named SWAN25F, earlier this year.
So far, spectroscopic observations of 3I/ATLAS have not detected dicarbon in the comet’s coma.
RELATED STORIES —James Webb telescope images reveal there’s something strange with interstellar comet 3I/ATLAS —NASA’s Hubble telescope reveals most detailed photos of interstellar visitor 3I/ATLAS to date —Interstellar comet 3I/ATLAS transforms into a giant ‘cosmic rainbow’ in trippy new telescope image Avi Loeb, an astronomer at Harvard University who is renowned for studying interstellar objects for possible signs of alien technology, has another explanation.
Last week’s total lunar eclipse produced some unexpected new images of comet 3I/ATLAS that suggest the “interstellar visitor” may be turning bright green as it nears the halfway point of its solar system journey. If verified, this surprising change is most likely the consequence of the comet getting closer to the sun, according to experts.
The comet 3I/ATLAS, which is about 7 miles (11 kilometers) wide, was first observed in early July and is speeding toward Earth at over 130,000 miles per hour (210,000 kilometers per hour) from outside of Jupiter’s orbit. Astronomers soon discovered that the blazing object was traveling through our galaxy in a single direction rather than coming from within our cosmic neighborhood. It was most likely ejected from a far-off Milky Way star system and is most likely much older than the solar system.
The comet will now approach Mars for a flyby next month before descending to its smallest distance from the sun in October. 28. The interstellar interloper has begun to grow a conventional cometary tail as it approaches the sun because it is absorbing more solar radiation, which causes more ice, gas, and dust to be expelled from its core.
But on Sept. 7, astrophotographers Gerald Rhemann and Michael Jäger captured fresh images of the comet over Namibia in the shadowy sky. The skies were darker than usual for the time of month when the full moon passed through the darkest area of Earth’s shadow, as seen in these photos taken during the “blood moon” total lunar eclipse. The resulting images display 3I/ATLAS in an unexpectedly emerald color.
The comet’s growing closeness to the sun may have caused it to “turn green” as new, rarer chemicals are released from its core, according to the new images, according to Spaceweather.com. Since no other photographers or observatories have yet to notice this change, it is still too early to say for sure.
See Also: Another controversial paper raises doubts about whether interstellar visitor 3I/ATLAS is actually “possibly hostile” alien technology.
Astronomers have previously observed a green glow emanating from a comet. A number of other emerald ice balls have passed by us in recent years, such as the appropriately named “green comet” C/2022 E3, which did so in early 2023. While astronomers saw another green comet, SWAN25F, earlier this year, the explosive “devil comet” 12P/Pons-Brooks also turned green as it approached the sun in 2024.
This uncommon coloring is most frequently caused by “dicarbon” in comet comas, which are clouds of gas and ice that encircle comets. This molecule, which has two atoms bound together, is also known as diatomic carbon. Pure carbon typically occurs in larger structures like diamonds or as single, unbonded atoms.
There has been no detection of dicarbon in the comet’s coma thus far in 3I/ATLAS spectroscopic observations. Nonetheless, Spaceweather . com representatives wrote that it’s possible the molecule was trapped beneath ice layers that have since melted due to solar radiation. Additionally, they stated that “the green glow might come from some other mix of gases or dust, mimicking a classic cometary color with unfamiliar chemistry.”.
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James Webb telescope images show that interstellar comet 3I/ATLAS is unusual.
—The most detailed images of interstellar visitor 3I/ATLAS captured by NASA’s Hubble telescope to date.
A strange new telescope image shows interstellar comet 3I/ATLAS changing into a massive “cosmic rainbow.”.
Avi Loeb, a Harvard University astronomer known for looking for evidence of extraterrestrial technology in interstellar objects, has another explanation. Cyanide, which the Very Large Telescope in Chile’s Atacama Desert detected in the comet’s coma in late August, may be the source of the color, he wrote on his personal blog.
To confirm the new coloration and determine what might be causing it, more observations and photographs will be required in the upcoming weeks.
Regretfully, the comet will soon pass the sun on the other side of Earth and be out of sight. In a few months, it will reappear just before it gets as close to Earth as it can in December, when it will be about 700 times farther away than the moon.
