Photo shows that the tail of interstellar comet 3I/ATLAS has grown by 3 million km

This event has piqued the interest of amateur astronomers and researchers who analyze and investigate the origin of interstellar comets. Until last week, it had no tail, even though it releases gas and water vapor through a natural process called sublimation when exposed to temperatures higher than those found outside the solar system.

In a recent study conducted by the Virtual Telescope Project in Manciano, Italy, the images of the comet were taken after “remote imaging with an ARTEC250+Paramount ME+C3Pro61000EC robotic unit, combined with sigma clipping of 18 exposures of 120 seconds,” as highlighted on the official website.

When the interstellar comet was photographed, it had a “bright moon (phase: 61%) 14 degrees above the eastern horizon, about 70 degrees away.” From this perspective, it was observed that the ion tail “extends at least 0.7 degrees in the northeast direction.” At the same time, “I saw its tail facing east-southeast.”

Gianluca Masi of the Virtual Telescope Project told the BBC’s Sky Night Magazine that he and his team managed to capture the first images of the object after its closest approach to the sun on 6 November. These images were faint, but a clearer image was obtained on November 11th.

“Thanks to its evolving geometry, we clearly detected the ion tail of 3I/ATLAS. Now, as the comet moves into the morning sky, the tail that was behind the core is becoming increasingly visible as seen from Earth at perihelion.”

After the passage of interstellar comet C/2025 V1 (Borisov), news broke about the increase in volume of the tail of comet 3I/ATLAS. The discovery was made by amateur astronomer Gennady Borisov, who reported its existence to the Astronomical Data Center between November 2 and 5. Because it is a relatively small celestial body, it had not received much attention until then.

The same people who discovered the second comet also discovered it in 2019, when they discovered the first interstellar visitor, 2I/Borisov. According to LiveScience, which compiled this information, 3I/ATLAS made its closest approach to Earth on Tuesday, November 11th, at a distance of 103 million kilometers, which is 270 times the distance of the moon. It is expected to reach perihelion (the closest point to the Sun) on Sunday, November 16th.