Mysterious interstellar object is morphing in unexplained ways as it moves closer to Earth

The latest image of the mysterious interstellar object racing through our Solar System^[1] has revealed it is changing shape and color.

A team of Austrian astronomers captured the object, known as 3I/ATLAS, on September 7, finding its once reddish glow has recently turned green^[2].

Scientists said these changes are unusual and not fully explained^[3] by current comet models. 

‘During the total lunar eclipse, we captured a detailed image of Comet 3I/ATLAS from the dark skies of Namibia,’ astronomer Michael Jäger shared. 

‘By combining multiple exposures in blue, green, and red light, we were able to clearly see the comet’s gas-rich coma.’

Data released this week by the ATLAS telescope team also showed that the cloud of light around 3I/ATLAS grew faster when the object was far from the sun and slowed down as it approached. 

The team suggested that this change happened^[4] because the object shifted from spreading sunlight off red dust on its surface to releasing small, bright icy particles, which made its surrounding plume more reflective.

3I/ATLAS is set to make its closest approach to Earth on December 19, 2025, at a distance of 168 million miles, the same distance between our planet and Mars. 

The latest image of the interstellar object racing through our Solar System shows it has lost its reddish hue and now glows green

Harvard physicist Avi Loeb shared the Austrian team’s developments in his latest blog post, suggesting the transformation from red to green-blue colors was due to the steep rise in the production of cyanide (CN), as reported by the Very Large Telescope on August 25, which found that 3I/ATLAS is emitting CN at 20 grams per second.

As 3I/ATLAS got closer to the sun, it released much more cyanide and nickel (without any iron), with the amount increasing very sharply, roughly following a pattern proportional to the ninth power of its distance from the sun, explained Loeb.

The physicist has suggested that 3I/ATLAS could be an alien probe, citing its massive size, extreme brightness, and missing tail.

However, the Austrian astronomers noted that the coma was clearly visible in their data. 

‘The tail documented by Hubble Space hardly grew any larger and only became slightly brighter,’ Jäger told the Daily Mail. 

‘At the beginning of September, the object reached the limit where gas-rich comets begin to become active. On August 28, we saw that the tail was getting brighter. A few days later, we saw the beginning of the development of a gas coma in images taken with a blue filter. 

‘The deeper images taken during the total lunar eclipse on September 7 already show a blue-green coma and a tail. All of this can be explained by the development of a comet. 

‘The object traveled through the depths of space for billions of years, was bombarded by radiation, and a thick crust formed, which is only now breaking open.’

3I/ATLAS is set to make its closest approach to Earth on December 19, 2025, at a distance of 168 million miles, the same distance between our planet and Mars

The transformation from red to green-blue colors has been linked to the steep rise in the production of cyanide (CN), as reported by the Very Large Telescope on August 25, which found that 3I/ATLAS is emitting CN at 20 grams per second

Unlike the first interstellar object, 1I/`Oumuamua, which showed no signs of gas or dust, and the second, 2I/Borisov, which behaved like a typical comet, 3I/ATLAS exhibits unique features, including the anti-tail, extreme color changes, and a massive coma. 

While the Austrian team has dismissed Loeb’s theory, the physicist said he is only looking at the present data.

Loeb recently cited the findings from the Very Large Telescope, highlighting how it detected an unusual nickel plume from the object.

Unlike natural comets, which always emit nickel alongside iron, 3I/ATLAS shows the metallic element without any detectable iron. 

Loeb explained that this nickel signature is a hallmark of industrial production of nickel alloys. 

‘Is this anomaly another clue for a possible technological origin of 3I/ATLAS?’ Loeb wrote in a blog post.

‘The paper suggests that chemical formation occurs through the nickel carbonyl channel, an extremely rare process in comets, but a standard technique in industrial nickel refining,’ he added.

The new study, published by astrophysicists in Chile late August, found that 3I/ATLAS is shedding nickel at roughly five grams per second and cyanide at 20 grams per second, with both rising sharply as the object moves closer to the sun.

Researchers noted that the mechanisms driving these emissions are not typical of natural cometary processes.

They hypothesized that nickel might be released from dust through gentle processes, such as sunlight, causing it to evaporate or breaking down small nickel-containing compounds.