A new image captured by robotic telescopes in Italy offers a breathtaking view of interstellar comet 3I/ATLAS (C/2025 N1 ATLAS). The striking visual reveals the visitor from another star system boasting an increasingly long and structured ion tail, suggesting heightened activity as it navigates closer to the sun.
The image, pieced together from a series of 18 exposures taken on November 10th, clearly shows a sharply defined ion tail stretching roughly half a degree across the sky. Despite some challenges – including the comet’s relatively low position near the eastern horizon and the brightness of a nearly full moon – astronomers were able to capture the impressive detail of the celestial object.
This expanding tail is telling a story about 3I/ATLAS’s journey. “Exploiting the unusual good weather of this season, we imaged the interstellar comet 3I/ATLAS (C/2025 N1 ATLAS) again, recording a much more developed ion tail,” said Gianluca Masi, founder and astronomer with the Virtual Telescope Project. “Looking at the picture, we see how the ion tail of 3I/ATLAS is clearly showing better and better.”
How Ion Tails Form:
The captivating blue hues of an ion tail arise from a fascinating process. As sunlight bombards the comet’s nucleus, it strips electrons from gases released by the icy visitor. This leaves behind charged particles known as ions, which are then propelled away by the continuous stream of charged particles flowing outward from the sun — what we call the solar wind. The resulting tail always points directly away from the sun, regardless of the comet’s direction of travel, showcasing a dynamic interplay between cosmic forces.
In contrast to the ion tail, the comet also displays a fainter anti-tail and a yellowish-white dust tail that curves gently along its orbit. The visible changes in 3I/ATLAS’s appearance point towards intensified sublimation – the process where frozen materials like carbon dioxide and dust vaporize due to solar heating. This material is then swept away by the solar wind, creating the dynamic tails we see.
A Rare Opportunity:
This interstellar visitor is only the third confirmed object of its kind ever detected. Unlike its predecessors, 1I/’Oumuamua (discovered in 2017) and 2I/Borisov (seen in 2019), 3I/ATLAS’s relative brightness allows for detailed study using ground-based telescopes. This presents astronomers with a precious chance to observe how an interstellar comet behaves under the influence of our sun.
Early observations suggest that 3I/ATLAS contains a significant amount of carbon dioxide ice, potentially offering clues about the conditions in its distant planetary system of origin. Studying this unique material could reveal insights into not only cometary formation but also how these icy bodies evolve beyond our own solar neighborhood.
