The European Space Agency (ESA) has finally shared new details about the mysterious interstellar visitor days after its closest approach to Mars.

On October 3, the object known as 3I/ATLAS passed within 18.6 million miles of Mars. While NASA swiftly shared images from its Perseverance rover on Mars, the European Space Agency (ESA) had remained silent until now.

The ESA’s ExoMars Trace Gas Orbiter (TGO) captured images of the object, appearing as a tiny, blurry white dot in a series of images.

The comet’s icy core, along with its halo of gas and dust, known as a coma, could not be distinguished individually. However, the faint glow stood out clearly against the dark backdrop of space.

Initially, scientists were uncertain whether the orbiters’ cameras would be able to capture the comet. These cameras are meant to photograph the bright, rocky Martian surface from a few hundred to a few thousand miles away, not a dim object millions of miles distant.

‘This was a very challenging observation for the instrument,’ said Nick Thomas, principal investigator of the CaSSIS camera. 

‘The comet is around 10,000 to 100,000 times fainter than our usual targets.’

The visible coma suggested that 3I/ATLAS is beginning to heat up as sunlight reaches its surface, causing ice to vaporize and release dust, which gives comets their ghostly appearance. 

The European Space Agency finally released images 3I/ATLAS, captured by a Mars orbiter 

Originating from outside our Solar System, 3I/ATLAS is only the third interstellar comet ever seen, following 1I/ʻOumuamua in 2017 and 2I/Borisov in 2019.

‘These comets are absolutely foreign,’ the ESA shared on Tuesday, referring to 3I/ATLAS as a ‘rare visitor.’

‘Every planet, moon, asteroid, comet and lifeform in our Solar System shares a common origin. 

‘But interstellar comets are true outsiders, carrying clues about the formation of worlds far beyond our own.’

ExoMars TGO captured the series of images with its Color and Stereo Surface Imaging System (CaSSIS), which was unable to distinguish the nucleus from the coma due to 3I/ATLAS being too far away.

However, the device was able to image the coma that spanned thousands of miles across. 

‘The full size of the coma could not be measured by CaSSIS because the brightness of the dust decreases quickly with distance from the nucleus,’ the ESA report shared.

‘This means that the coma fades into the noise in the image.’

3I/ATLAS made its closest approach to Mars on October 3 and is set to continue through our Solar System

NASA was quick to release images of the object snapped by its Perseverance rover on Mars. The agency uploaded them over the weekend 

Typically, material from the coma is swept into a long tail that can stretch for millions of miles as the comet moves closer to the sun. 

‘The tail is much dimmer than the coma. We can’t see the tail in the CaSSIS images, but it may become more visible in future observations as the comet continues to heat up and release more ice,’ shared the ESA. 

The images have flooded X, where one user posted: ‘ESA Finally Releases Images of 3I/ATLAS. After days of silence, ESA finally broke the blackout.’

The ESA’s report comes days after NASA released its view of the visitor.

Harvard astrophysicist Avi Loeb, who has been convinced that the object could be an alien craft or probe, analyzed the Perseverance rover’s photos by calculating its distance, speed, and camera settings.

According to his initial study, Loeb was not convinced 3I/ATLAS is actually a massive cylindrical object, noting that the strange shape might have been a trick of the rover’s camera stretching out its shape.

He explained that the apparent cylinder from the rover’s ‘Navcam’ was likely caused by the camera stacking hundreds of images of 3I/ATLAS over a period of about 10 minutes, making it look more like a log than a ball.

The professor added that 3I/ATLAS is likely smaller and rounder, but still massive, with a potential diameter of more than 28 miles across.

Dr Horace Drew, a retired senior researcher at Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO), noted that the mysterious green glow seen in some images could be a result of the object being an interstellar spacecraft coated in nickel.

Color-enhanced images shared by multiple social media users revealed a strange green glow around 3I/ATLAS

Drew explained that humans use the same practice on Earth-made space technology on a much smaller scale.

‘It is not a ‘comet,” Drew declared on a post on X Monday morning.

Drew disagreed with Loeb’s conclusion that the cylindrical shape was a result of the Mars rover sending back a stretched image over several minutes, claiming that an amateur astronomer on Earth captured a similar shape with their telescope.

‘We can see an extended white shape, with a green coma outside. Not a small white ball,’ Drew explained in a post about the astronomer’s photograph.

Drew, who earned his PhD in chemistry from the California Institute of Technology, added that previous images of the interstellar object were allegedly from a ‘head-on view’ and didn’t capture its shape from the side, like the new photos from Mars.

Loeb said he’s excited about another image taken by a different Mars camera, called HiRISE, which has better resolution and could show 3I/ATLAS more clearly.

That image is being sent back to Earth by the Mars Reconnaissance Orbiter (MRO) and has yet to be released by NASA.