Comet 3I/Atlas breaks up as it passes closest to the Sun
Click for original image.
Sometime on November 11, 2025, the nucleus of interstellar Comet 3I/Atlas broke into three pieces as it passed through its closest and hottest point to the Sun.
The image to the right, cropped and reduced to post here, comes from images of the break-up taken by the Virtual Telescope project, which gathers data from many small telescopes remotely.
From the first link, translated by Google from the Italian:
Its trajectory led it, in early October, to pass through a point of minimum distance from the Sun (perihelion) quite close to our star, about 0.33 astronomical units, just outside the orbit of Mercury. Because of this “short” distance from the Sun, it experienced high solar irradiation, which caused a significant increase in the temperature of the surface and internal layers of the nucleus.
These are precisely the conditions under which a “breakup” event is expected: depending on the internal properties of the nucleus—namely, its porosity, its state of cohesion, its composition, and the percentage of ice—it is possible that the increase in temperature could cause significant “outgassing,” a sudden and violent outflow of gaseous and dusty material, and the consequent fragmentation of the nucleus, sometimes into a few pieces of roughly similar size, sometimes into a cloud of fragments and debris that spread along the trajectory of the original comet.
…”From an initial quick analysis of the images, we can confirm that there are certainly two fairly similar pieces, whose brightness maxima are separated by approximately 2,000 km (distance projected on the star field); “Furthermore, we can intuit the presence of a third, smaller and fainter fragment to the left of the pair,” observes Mazzotta Epifani.
The big scientific take-away from this interstellar comet remains the same. Despite coming from many light years away and traveling for at least many millions and possibly billions of years in space, it is remarkably similar to comets in our own solar system. It has its own unique properties, as all comets do, but apparently, our solar system resembles the rest of the galaxy quite closely. Or possibly the galaxy resembles our solar system. Either way, we have confirmation that what we have here is like the rest of the Milky Way.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Click for original image.
Sometime on November 11, 2025, the nucleus of interstellar Comet 3I/Atlas broke into three pieces as it passed through its closest and hottest point to the Sun.
The image to the right, cropped and reduced to post here, comes from images of the break-up taken by the Virtual Telescope project, which gathers data from many small telescopes remotely.
From the first link, translated by Google from the Italian:
Its trajectory led it, in early October, to pass through a point of minimum distance from the Sun (perihelion) quite close to our star, about 0.33 astronomical units, just outside the orbit of Mercury. Because of this “short” distance from the Sun, it experienced high solar irradiation, which caused a significant increase in the temperature of the surface and internal layers of the nucleus.
These are precisely the conditions under which a “breakup” event is expected: depending on the internal properties of the nucleus—namely, its porosity, its state of cohesion, its composition, and the percentage of ice—it is possible that the increase in temperature could cause significant “outgassing,” a sudden and violent outflow of gaseous and dusty material, and the consequent fragmentation of the nucleus, sometimes into a few pieces of roughly similar size, sometimes into a cloud of fragments and debris that spread along the trajectory of the original comet.
…”From an initial quick analysis of the images, we can confirm that there are certainly two fairly similar pieces, whose brightness maxima are separated by approximately 2,000 km (distance projected on the star field); “Furthermore, we can intuit the presence of a third, smaller and fainter fragment to the left of the pair,” observes Mazzotta Epifani.
The big scientific take-away from this interstellar comet remains the same. Despite coming from many light years away and traveling for at least many millions and possibly billions of years in space, it is remarkably similar to comets in our own solar system. It has its own unique properties, as all comets do, but apparently, our solar system resembles the rest of the galaxy quite closely. Or possibly the galaxy resembles our solar system. Either way, we have confirmation that what we have here is like the rest of the Milky Way.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Pity we can’t get samples from it. Not just to get a possible idea of the solar system it came from but its been traveling through interstellar space for a LONG time and who knows what it may have interacted with?
I read of an idea once that if you take a ride on a long duration comet whose apogee is in the Oort cloud towards Alpha Centauri you might run into a comet from its Oort cloud. You could jump to that one and ride into that system. It would be a very long ride but you expend very little energy.
Incorrect. Comet C/2025 K1 (ATLAS) is not interstellar object 3I/ATLAS also designated C/2025 N1. The latter, in addition to following a hyperbolic trajectory through the solar system rather than elliptical solar-bound orbit, also passed its perihelion near the orbit of Mars (vs. 0.33 AU for C/2025 K1) and hasn’t (thus far) broken up.
I was wondering how Avi Loeb was going to explain it but McNeil has pointed out this is not the interstellar object Loeb is excited about.
This comet is more local though this is the first time it has visited the inner solar system.
From the article (with help from Google Translate):
Comet C/2025 K1 (ATLAS) was discovered in May 2025 thanks to the ATLAS (Asteroid Terrestrial-Impact Last Alert System) program, a NASA-funded research program that uses four telescopes (two in Hawaii, one in Chile, and one in South Africa) to automatically scan the sky every night for asteroids that could potentially threaten our planet. One of the scientific spin-offs of this program is the continued discovery of comets, such as C/2025 K1 (ATLAS).
It is a comet classified as “hyperbolic,” meaning that during the time span of observations, from its discovery to early November, it moved in an open orbit. In fact, backward numerical integrations of its motion, before it entered the innermost regions, tell us that it is a comet originating from the Oort cloud , at the outer edges of the Solar System, and that this is likely its first transit through our region: it is a “dynamically new” comet.