As the interstellar comet 3I/ATLAS prepares for its closest approach to Earth on December 19, it is being monitored not just by space agencies but also the United Nations.
The comet will come within roughly 167 million miles (270 million kilometers) of our planet. Telescopes around the world will track it so astronomers can pinpoint its location and make predictions about future objects like it.
The UN’s International Asteroid Warning Network, or IAWN, is about halfway through its 3I/ATLAS observing campaignand expects to publish its findings in a peer-reviewed journal next year, according to James Bauer, a small-bodies node principal investigator at IAWN and a research professor in the University of Maryland’s astronomy department, who spoke to Live Science.
The network consists of more than 80 observatories and citizen scientists around the world conducting active research on near-Earth objects, such as comets and asteroids.
Why IAWN is tracking 3I/ATLAS
The International Asteroid Warning Network is a joint effort by the United Nations and NASA to study interstellar objects, using 3I/ATLAS as its test case to work on and potentially improve future comet exploration and the understanding of such interstellar visitors. Despite making its closest approach Friday, 3I/ATLAS will remain approximately 168 million miles away from Earth.
According to the IAWN’s official website, the campaign is described as: “This 3I/ATLAS campaign is the 8th IAWN observing exercise since 2017 – IAWN holds these exercises roughly once a year.” The network had already planned to conduct a comet campaign in Fall 2025 to practice tracking comets, and with the observation of 3I/ATLAS, their plan was set into motion.
By studying 3I/ATLAS and its trajectory, the IAWN hopes to improve how well scientists can measure a comet’s position. The network will “target comet 3I/ATLAS to exercise the capability of the observing community.”
Campaign timeline and goals
The 3I/ATLAS comet campaign began on November 27, with a mid-campaign check-in on December 9, and a closing date set for February 3. NASA coordinates the campaign, and 3I/ATLAS is the first interstellar object to be studied since the launch of the campaign in 2017.
Besides studying their first interstellar object, the IAWN campaign also tracked asteroid Apophis in 2020 and 2021. The network will set up new campaigns in 2027 and 2029, when the asteroid is expected to make another approach toward Earth.
Bauer explained the purpose and future implications of these campaigns: “The idea behind these campaigns is really to strengthen the technical capabilities for measuring sky positions, which we call astrometry, for asteroids and comets.” Researchers working on the project will test a new astrometry technique to study the trajectory for 3I/ATLAS.
Why 3I/ATLAS is an ideal test case
The observations will be crucial for the future of astronomy because they will allow experts to understand how to send spacecraft to comets in the future. “We want the community to use the latest and greatest techniques,” Bauer added.
3I/ATLAS became a perfect test object for their campaign because it coincided well with their campaign’s schedule. Studying a comet’s position is difficult due to its changing brightness and other variables, including the properties of its coma (cloud of gas and dust) and its tail. Because of all these factors, its position and size are difficult to track.
3I/ATLAS, despite originating outside the solar system, behaved like a “comet’s comet,” showing characteristics similar to a normal comet. Consequently, researchers hoped to track it to understand the behavior of a natural comet.
Bauer concluded by appreciating the interest in the IAWN campaign, hoping it will result in improving Earth’s “vigilance” toward such objects in the future.
