As interstellar object 3I/ATLAS approaches its closest point to the Sun next month, the mysterious visitor continues to fascinate astronomers.
The object, which is broadly believed to be a comet that came to us from outside the solar system, has already been observed changing shape. Its tail has grown longer, and its coma — a large atmosphere of gas and dust that surrounds its nucleus — has become more pronounced. Those are expected characteristics from a comet ripping by the Sun at ludicrous speeds, though numerous readings by sensitive space telescopes have also found it to have unusual properties that will be studied for years to come.
In the latest twist, this week, comet hunter Michael Jäger and his colleagues "took advantage of the total lunar eclipse to take a deep image of Comet 3I/ATLAS under the dark skies of Namibia," according to a recent forum exchange.
Their observations showed that the object's coma has now transitioned from giving off red light to green, yet another fascinating wrinkle in the rare interstellar visitor's odyssey through our solar system.
As Harvard astronomer and noted alien hunter Avi Loeb pointed out in a recent blog post on the findings, this could be due to a "steep rise in the production of cyanide."
Scientists hypothesize that the production of the chemical, alongside nickel, are increasing dramatically as 3I/ATLAS approaches the Sun.
Data by the ATLAS telescope team, which first spotted the object and after which the space rock is named, suggests that the object's "anomalous evolution" is shifting from "scattering of sunlight by dust lifted from a reddened surface to the production of small, optically bright icy grains, which changed the opacity of the plume of materials shed off by 3I/ATLAS," per Loeb.
While Loeb has repeatedly raised the possibility that 3I/ATLAS might be an "extraterrestrial artifact" that was sent to us by an intelligent alien race, observations are building a stronger and stronger case that it's merely a comet — albeit one from far beyond our solar system.
To Loeb, though, it's still an outlier. For one, observations have shown that the object is "dominated by carbon dioxide," as Loeb explains, making up a whopping 87 percent of its mass.
The astronomer has also found that its orbital path, which takes it relatively close to Mars, Jupiter, and Venus, is extremely unusual, making "3I/ATLAS interestingly anomalous relative to familiar icy rocks."
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