Next Friday, December 19 will be a key date for astronomers around the world. On that day, Comet 3I/Atlas (an object of interstellar origin that travels through space from outside the Solar System) will reach its minimum distance from Earth on its current trajectory. The proximity of this unique comet has prompted an unprecedented tracking operation led by the UN’s International Asteroid Warning Network (IAWN), coordinated by NASA, with the goal of improving near-Earth object (NEO) tracking techniques.
A visitor from another world
Comet 3I/Atlas is not just any comet. It was discovered in late June and is, so far, the third in recorded history to come from outside the Solar System, after 1I/’Oumuamua in 2017 and 2I/Borisov in 2019. Despite its unusual origin, it behaves like a typical comet: as it approaches the Sun, its surface releases gas and dust, generating a coma, that characteristic nebulous envelope that makes these celestial bodies visible.
Despite this habitual behavior, its interstellar origin makes it an object of enormous scientific value, since it can offer clues about the physical and chemical conditions in stellar systems other than our own.
Why the UN is behind 3I/Atlas
The comet’s presence has activated the IAWN, an international network of more than 80 observatories and numerous scientists and amateurs dedicated to tracking near-Earth objects. The mission of this network is to optimize and refine NEO tracking methods to accurately identify the trajectories of comets and asteroids that may approach our planet.
In the case of 3I/Atlas, in addition to its scientific interest because of its origin, the follow-up campaign allows testing a new astrometry technique specifically designed to trace its trajectory. According to James Bauer, principal investigator of the IAWN and professor of astronomy at the University of Maryland, this initiative “has a high value” because it could improve the prediction of other cosmic approaches, as happened with comet YR2024, which generated expectation months ago.
The idea is that the data obtained will allow to refine algorithms and methods that could also be used to plan future space missions to similar bodies, as has been done in the past with comets and nearby asteroids, for example NASA’s mission to the asteroid Bennu.
A major technical challenge
Observing 3I/Atlas is not straightforward. Although its passage at 270 million kilometers (a safe distance from Earth) does not pose a physical threat, accurately measuring its position and trajectory poses difficulties.
This is due, in part, to the variability of its brightness and fluctuations in its coma, the cloud of gas and dust that envelops the comet as it heats up as it approaches the Sun. The coma can increase in size and alter the way light is reflected, complicating astronomers’ work to track the comet’s exact nucleus.
These complications are part of the challenges that IAWN and partner observatories hope to overcome with this campaign, as learning to deal with these types of variations will be key to future NEO surveillance operations.
What’s at stake for science
Although 3I/Atlas poses no threat to Earth in its close flyby, its tracking offers important benefits:
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Improve techniques for tracking and predicting trajectories of celestial objects.
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Improve international response to possible future threats from nearby asteroids or comets.
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Increase the accuracy of astronomical models used to plan space missions.
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To increase knowledge about bodies of interstellar origin, which may contain essential information about the formation of stellar systems other than our own.
International collaboration on projects such as this one demonstrates that near-Earth space monitoring is a joint effort that goes beyond the borders of any one country.
When will we know more?
Although the observing campaign is intense, the IAWN has been clear about the timeline: the data collected on the position and trajectory of 3I/Atlas and its interpretation will not be made public through a scientific study until early next year.
This means that astronomy enthusiasts and the scientific community will have to be patient for detailed results and final conclusions. However, comet tracking is already providing an enormous amount of information that will be rigorously analyzed in the coming months.
