Is the Newly Discovered Sun-Grazer C/2026 A1 (MAPS) Related to 3I/ATLAS?
The latest two puzzles about 3I/ATLAS stem from its large inferred size and mass (as reported here). First, its parent population cannot be supplied by the mass reservoir of planetary systems around old metal-poor stars (as I argued here). Second — its mass of a billion metric tons is 5 orders of magnitude larger than the final mass of 1I/`Oumuamua, implying that we should have discovered a hundred thousand interstellar objects on the mass scale of 1I/`Oumuamua before seeing one giant object like 3I/ATLAS (as I argued here).
Altogether, the full list of 22 anomalies for 3I/ATLAS (summarized here) is particularly timely, as the mysterious object comes closest to Jupiter today on its way out of the Solar System. If the passage near Jupiter will not reveal any new insight on 3I/ATLAS, we will be left with many questions about its nature and origin.
Can we hope to learn more about future interstellar visitors?
The best way to examine visitors to our cosmic back yard is to interrogate them under extreme heat. This opportunity is realized for Sun-grazing trajectories. In 2019, I co-authored a paper (published here) with my then-postdoc, John Forbes, which explored the statistics of close encounters between interstellar objects and the Sun. Objects similar to 1I/`Oumuamua collide with the Sun once every 30 years. A Sun-grazing passage would vaporize any solid surface, unraveling the composition and structure of the object’s interior by detailed observations from the Inouye Solar Telescope (DKIST) in Hawaii or the Solar and Heliospheric Observatory (SOHO) in space.
On April 4, 2026, we will have a unique opportunity to witness a rare Sun-grazing encounter by the large object, C/2026 A1 (MAPS), which was discovered on January 13, 2026 from the AMACS1 Observatory in Chile. The object will pass within 161,000 kilometers (23.1% of the Solar radius) from the surface of the Sun. From the vantage point of Earth, the object will enter Solar conjunction behind the Sun on April 4, 2026 at 13:19 UTC and appear in front of the Sun at 15:34 UTC, in both case being separated by 0.04 degrees from the center of the Sun.
The unusual trajectory of C/2026 A1 (MAPS) suggests that it is a member of a yet unknown group of comets that are bound gravitationally to the Sun. Could it be a fragment that broke off 3I/ATLAS and was launched into a bound orbit around the Sun? Probably no, because its inferred diameter of somewhat less than 2.4 kilometers is comparable to that of 3I/ATLAS, and the orbital inclination of C/2026 A1 (MAPS) is 144.5 degrees, about 30.6 degrees away from the 175.1 degrees inclination for 3I/ATLAS.
C/2026 A1 (MAPS) will pass through the solar corona and reach perihelion with a peak speed of 557 kilometers per second (0.2% of the speed of light) on 4 April 2026 at 14:21 UTC. At that time, it will be separated from the center of the Sun by 0.57% of the Earth-Sun separation. It will then make closest approach to Earth on 5 April 2026 at 23:56 UTC when it will be at a distance of 143.8 million kilometers (96.1% of the Sun’s distance) from Earth.
Observing the fireworks as this object burns up and breaks close to the Sun will reveal new details about its composition and material strength.
Before my morning jog at sunrise today, I received the following uplifting email about C/2026 A1 (MAPS):
“Dear Professor Loeb,
I want to truly thank you for your intellectual courage. In a field that too often punishes curiosity, you have chosen the path of truth over comfort and you have had a profound impact on our children. We have been watching you refuse to dismiss the unexplained and face backlash from a stagnant scientific community. This rare quality has given children around the world the conviction that pursuing truth is worth the cost of facing criticism or being unpopular. You are truly one of the great scientists of our time and one can only hope that the censorship and elitism we see in the science community specifically and society as a whole can be diminished.
After seeing the myriad anomalies with 3i ATLAS, we have been applying this same curiosity to other objects passing through our celestial neighborhood. There has been relatively little coverage of another unique guest- C/2026 A1 (MAPS). Headlines have been quick to file it under “Kreutz sungrazer” and move on but the data resists that tidy label. Its orbital period of nearly 1,900 years is at least twice as long as any other Kreutz members. It was detected 81 days before perihelion at a distance of greater than 2 AU!! That’s significantly farther from the Sun than any previously known Kreutz comet and suggests unusual size or extraordinary activity. And now its brightness is running dramatically ahead of predictions, currently around magnitude 9.9, with no satisfying conventional explanation for why it is brightening so aggressively at this stage.
These anomalies raise questions I would love your perspective on:
1. Given that MAPS appears orbitally inconsistent with the Kreutz family of comets, should it be treated as an unclassified object until better data is available?
2. Could the runaway brightening indicate something unusual about the composition or structure of the nucleus that standard cometary models don’t account for?
3. Can this possibly survive its close encounter with our sun and put on the greatest show of the millennium?
You have shown that the most important questions are often the ones we are most reluctant to ask. My family is grateful for that example.
With deep respect and love,
Chris and Stephanie Francois and our kids
Joshua, Nicholas, Savannah, Thomas, Enzo and Sophia”
Shortly afterwards, I had received the following email from the poet Alan Wagstaff in New Zealand:
“Dear Dr Loeb,
Here’s my response to your oft-mentioned ideas about confirmation bias in science.
It’s a formal sonnet.
I hope it communicates. It’s a complex idea and has a slight humorous edge.
Best wishes
Alan
‘A man sees what he wants to see…’ *
I’m nonplussed since you visited my home,
in part, because you dropped in — unannounced.
It seems so weird: you never said ‘shalom’,
‘aloha’, or ‘hello’. Instead, you bounced
and squeaked, high pitched, and droned, bee-like, off-key.
You hovered in mid-air and softly whined.
“No chance,” I mused, “that you could be E.T!”
For certain, you’re not extra-humankind,
since mainstream physics locks us in a vault,
which shuts-out any off-world creatures’ whims.
Your purple tendrils, signing us to ‘halt’,
were probably wisteria, not limbs.
Since you’re not human from some unknown tribe,
you must be Terra-cryptid, I decide.
Alan Wagstaff
* from ‘The Boxer’ Paul Simon
ABOUT THE AUTHOR
Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
Professional website:
https://lweb.cfa.harvard.edu/~loeb/
Social media:
https://avi-loeb.medium.com/
https://www.youtube.com/@ProfessorAviLoeb
https://open.spotify.com/show/1zhndXkvSY2b8FdjspFpCd
https://x.com/ProfAviLoeb
