3I/ATLAS Update: UN Confirms Comet Is Subject Of Formal Planetary-Defense Exercise
The United Nations, through the International Asteroid Warning Network (IAWN), has formally confirmed that the interstellar comet 3I/ATLAS (C/2025 N1) will be the focus of a meaningful planetary-defence exercise. The campaign, designed to refine astrometric measurement techniques, will run from November 27, 2025, through January 27, 2026.
While 3I/ATLAS currently poses no threat to Earth – its closest approach on December 19, 2025, will be approximately 270 million kilometers – its unique characteristics make it an ideal test case.The exercise aims to improve the accuracy of predicting the trajectories of comets, which present distinct challenges compared to asteroids.
According to a Minor Planet Electronic Circular (M.P.E.C.2025-U142) issued by the International astronomical UnionS Minor Planet Center,comets are “extended bodies featuring comae and tails” that can ”systematically pull centroid measurements off their central brightness peak,making trajectory estimation more complex.” This means determining a comet’s precise position is more difficult than with a point-like asteroid.
The campaign’s core objective is to introduce and refine “methods for improving astrometry from comet observations.” This practise is considered crucial for ensuring the global astronomical community can rapidly and accurately assess the trajectory and potential impact probability of any future, possibly hazardous Near-earth Object.
The IAWN announced the observing window will span two months, allowing for a comprehensive exercise of international capabilities. A preparatory workshop was held to align participants on objectives and methodologies.
key dates for the 3I/ATLAS Comet Astrometry Campaign are as follows:
* Registration Deadline: November 7, 2025, 17:00 UTC
* Comet Astrometry Workshop: November 10, 2025, 15:00 UTC
* Kick-Off Email Notification: November 25, 2025
* Observing Window Opens: November 27, 2025
* Mid-Campaign Check-In: December 9, 2025, 15:00 UTC
* Observing Window Closes: January 27, 2026
* Close-Out telecon: February 3, 2026, 15:00 UTC
This exercise is a demonstration of global preparedness, stress-testing the systems designed to protect Earth from potential future threats. The work also strengthens collaboration between space agencies (through the Space Mission Planning Advisory Group – SMPAG) and the diplomatic arm of the United Nations (the United Nations Office for Outer Space Affairs - UNOOSA), highlighting planetary defence as a continuous and coordinated international effort.
[Image of 3I/ATLAS with caption: 3I/ATLAS. Paul Craggs/X]
[Embedded YouTube video: https://www.youtube.com/watch?v=a7ejDvp3UvQ]