A stunning new image of Comet 3I/ATLAS reveals a glowing green interstellar visitor hiding its tail. Captured using the Lowell Discovery Telescope, this rare comet offers insights into cosmic chemistry, light filters, and its mysterious irradiated crust.

Patrick Pester published it 7 hours ago.
In what is entering a critical observation period with respect to the interstellar visitor, a researcher has photographed a green-glowing comet 3I/ATLAS with its tail concealed in a new image with the powerful Discovery Telescope of the Lowell Observatory.

Discovery and Initial Observation of the Green-Glowing Comet

The discovery of a new image of comet 3I/ATLAS has showed that the visitor in the stars is glowing green, and concealing its tail, although that is no indication that anything is wrong with it.

Qicheng Zhang, a scientist in the Lowell Observatory in Arizona, made new observations of the comet with the powerful Discovery Telescope on Wednesday (Nov. 5) when the comet was moving away as the sun. The comet has not been seen now for some time, but it has just re-appeared, rounding the opposite side of our star.

Why the Comet Appears Green

Comets become gaseous, or coma, when they move near the sun. This comet becomes brighter and larger as the sun warms up ice and other substance on the comet which evaporate into gases that astronomers are able to see. Here, the sky is brightest when seen through a green color filter, as is the case with most of the comets which travel near our star.

Zhang filtered the particles to identify diatomic carbon (C2) particles, which are green. He observed that the comet has a bunch of large molecules which contains carbon and hydrogen (hydrocarbons). And as the comet approaches the sun, ultraviolet (UV) light disintegrates these molecules.

The Mystery of the Hidden Tail

The same reason is that, as Zhang in Live Science explained, we get sun burnt when we stay in the sun too long without a sunscreen. The UV rays are killing our DNA [in our skin cells] that is a sort of similar type of molecule in the sense that it is big and made of carbon.
When this occurs on a comet, there is a fraction of the molecule fragments that are two carbon atoms glued together or diatomic carbon that are discovered by astronomers without much difficulty.
The image does not seem to have a dust tail in the comet, but there it is. In a comment, Zhang observed that on close examination of the picture, one will notice that the left side of the comet is slightly brighter than the right. That is due to the fact that we are looking more or less at the tail straight on, and that the tail is literally behind the comet, which is bending slightly out to the left. That is, it is no reason to get excited over the apparent absence of a tail of the comet.

Comet 3I/ATLAS: An Extraordinary Interstellar Visitor

Since then, Comet 3I/ATLAS has turned into a cosmic star due to its discovery in July. Much of this buzz is due to the speculation that the comet is an alien craft, although the majority of the astronomers are sure that the alien in the interstellar is a comet of a distant star system belonging to the Milky Way.

It would also be a travesty to call 3I/ATLAS an ordinary comet though. The comet is the third and last interstellar visitor on record, and may possibly be the most ancient comet ever observed, and it is possible that one study estimates that it is approximately 3 billion years younger than the solar system.
It is only days since Comet 3I/ATLAS re-emerged on Earth and after briefly fading behind the sun, it came as close to our star, called perihelion, on October 29. This post-perihelion period presents a significant opportunity to the astronomers who would want to know more about the gases and composition of the comet so that in the process they can be most active during the period of perihelion.

Recent Observations and Scientific Insights

Incident research implied that over an extended period of time undergoing space radiation exposure, comet 3I/ATLAS has acquired a thick irradiated crust that is no longer reflective of its home star system. This crust, had it been confirmed, would imply that scientists will face greater difficulty in the origin of 3I/ATLAS since it will be releasing irradiated material instead of pure material of its home star system.
In the same manner, Zhang used Lowell Discovery Telescope to make a first optical, post-perihelion view of 3I/ATLAS on Earth, on Halloween (Oct. 31). Like in his initial observation, the new one was performed in the morning twilight. It is the northward movement of the comet that is traveling out of our view, towards the northeastern horizon. At the time one can see the comet early in the morning when the comet is coming up out of the horizon.

Zhang photographed the comet in various filters. His carbon diatomic picture, as he initially introduced to his Cometary blog on Wednesday, is approximately what the comet would appear to be in case humans could view it with the naked eye.
On 28 October, Zhang and his co-author uploaded a preprint to arXiv in which they proposed that comet 3I/ATLAS was fast growing brighter before perihelion and was noticeably bluer than the sun. The fact that the color in the new picture is green does not imply that the comet turned to green after perihelion, it could have turned to green at some point before perihelion.
The new observation was accredited by Zhang as, in the astronomical context, bluer or reddener usually denotes longer (red) and shorter (blue), wavelengths of light, which the new observation was. Viewed through bluer filters than redder ones the comet is much brighter, though the former is rather a composite of green and blue than a true blue, and is not so sensitive to pure blue.

Best, as seen through the blue filter, we have, Zhang said.
According to Zhang, one of the largest telescopes was the Lowell Discovery Telescope that was able to point sufficiently close to the horizon to observe the comet 3I/ATLAS immediately after perihelion. But he has pointed out that the comet has now reached a high enough altitude above the horizon that it can be observed by a variety of large telescopes – small personal telescopes with a 6-inch (15 centimeters) lens can see it.