Even the Sun doesn't take: what is known about comet 3I/ATLAS, which survived a stellar plasma ejection

Confirmation of this astonishing cosmic event was provided by a video published by the Solar Astronomy Laboratory of the Space Research Institute of the Russian Academy of Sciences.

The Sun is not captured in the video—it's hidden behind the instrument's disk—but its violent ejections are visible all around: billowing plumes of plasma emanating from the depths of the star. It's there, in the blinding light, where even large celestial bodies are virtually impossible to discern, that 3I/ATLAS is currently hiding.

The recording was obtained using the LASCO/C3 coronagraph , a unique instrument installed on the SOHO orbital observatory. Its purpose is to detect faint objects near the solar disk, where the background brightness is millions of times brighter than the reflected light from comets and asteroids. However, even LASCO was unable to immediately detect the interstellar visitor.

Astronomers used a special technique: they combined twenty frames for each moment in time —ten before and ten after. This method eliminates random noise and enhances the constant signal. And then, a miracle happened: a faint trace appeared on the screen—the very same 3I/ATLAS , arriving from the depths of the Galaxy.

The video showed that the interstellar object was still moving along its predicted trajectory, maintaining stability and overtaking distant stars in the footage. Its signal was so weak that, according to scientists, the instrument was literally detecting individual photons, but this was enough to draw the main conclusion: 3I/ATLAS survived the solar plasma impact .

On October 21, a powerful coronal mass ejection occurred from the far side of the Sun, ejecting a gigantic cloud of hot material into space. Calculations predicted that it should have reached the comet on October 24–25 and, theoretically, destroyed it if the nucleus truly consisted of loose ice and dust. However, the images show the object intact.

Astronomers have tried to detect the slightest changes in brightness to determine whether it has begun to disintegrate, but it is impossible to obtain precise data. Fuzzy outlines, apparent fragments— almost certainly processing artifacts rather than actual signs of destruction.

Unfortunately, further observations were not possible— 3I/ATLAS moved beyond LASCO's field of view . Still, two consecutive days of observations is a rare success. Scientists note that observing the dynamic motion of such a faint interstellar body is "a true miracle of observational astronomy."

Astronomers now have to wait until mid-November , when the comet will begin moving away from the Sun and become visible to Earth-based telescopes again. There is hope that the small satellites of the PUNCH mission, designed to study the solar wind, will also be able to provide some data about it.

3I/ATLAS became the third known interstellar traveler to visit our Solar System, following 'Oumuamua and Comet Borisov. Its resilience is astonishing: even the impact of a plasma storm could not destroy the body hurtling from the void between the stars.

• ATLAS (Asteroid Terrestrial-impact Last Alert System) is an automated sky observation system developed in Hawaii. Its primary goal is the early detection of asteroids that could potentially pose a threat to Earth.

• 3I/ATLAS received the prefix "3I" because only two interstellar objects had been discovered before it:

  1. 'Oumuamua (2017) is the first known interstellar object with an unusual elongated shape.

  2. 2I/Borisov (2019) is the first interstellar comet-like object with clear signs of cometary activity.

1. Origin:

   The object, as noted above, originated from beyond the Solar System. Its trajectory is hyperbolic, indicating an interstellar origin: it is not gravitationally bound to the Sun and does not orbit it like a typical asteroid or comet.

2. Form and appearance:

   The object's exact shape is still unknown. Observations show activity typical of comets: ejections of gas and dust as it approaches the Sun. This makes it resemble a comet, but with an unusual interstellar origin.

3. Speed ​​and trajectory:

   The object is moving at a high speed relative to the Sun—significantly higher than the speed of typical comets in the Solar System. Its trajectory is hyperbolic: after passing its closest point to the Sun (perihelion), it will leave the Solar System forever.

4. Scientific value:

   • Studying 3I/ATLAS provides information about the composition and structure of matter outside the Solar System.

   • Comparing its chemical composition with comets and asteroids in the Solar System provides clues to understanding the formation of planets and objects in other stellar systems.

   • Given that such objects are extremely rare, each new encounter is a unique opportunity for astrophysics.

5. Observations:

   Video and motion data are often obtained using coronagraphs such as LASCO on the SOHO satellite , which allow objects near the Sun to be seen while hiding the star's bright disk.

Yesterday, a new powerful explosion was detected on the far side of our star. Activity in this region, invisible to Earth, has been ongoing for about ten days after a large sunspot group, number 4246, moved from the side facing us onto it.

According to observations, the center has produced several high-class X-ray flares during this time. One of these, which occurred on October 22, is estimated to have reached X10 intensity. Although the region itself is currently hidden from view from our planet, plasma emissions extend far beyond the solar disk and are recorded by telescopes and coronagraphs.

Analyzing the direction of the emissions allows us to track the movement of the active center. While ten days ago the plasma was flowing to the right, after the explosion last night the material is already flowing to the left, indicating that the center has almost crossed the solar disk. By Saturday, it is expected to emerge onto the visible side of the Sun at its eastern edge, at which point the processes will become observable. In 5-7 days, the emissions may begin to influence the geomagnetic state of our planet. It remains to be seen how much energy remains by the time it emerges.

As early as October 28, astronomers observed a noticeable increase in geomagnetic activity after several quiet days. The Earth's magnetic field is responding to the increasing solar wind, but so far, everything is within normal limits— the geomagnetic disturbance index has approached the Kp=4 level , which separates a quiet state from a disturbed one, but has not yet crossed it.

The cause of the changes is a large coronal hole on the Earth-facing side of the Sun, through which plasma streams are ejected into space. Currently, the solar wind speed is low, and the Earth's magnetosphere is deflecting the impacts without much strain. However, experts expect short-lived geomagnetic storms to be possible as early as tomorrow or the day after.

Overall, solar activity remains low, and this can be considered a temporary episode. Astronomers are eagerly awaiting the emergence of the very same solar flare centers that struck 3I/ATLAS from the far side of the star last week. Those living in northern latitudes, especially in regions above the Arctic Circle, should be on guard: even with the current low activity, the chance of seeing the northern lights in Murmansk today is up to 30-40%.