An enigmatic visitor from deep space, racing through our solar system, has captured the attention of astronomers—and the public’s fascination—revealing new clues about its mysterious nature.
Since its discovery in July 2025, the interstellar object known as 3I/ATLAS has provided astronomers with a rare and unprecedented glimpse into the behavior of an object from beyond our planetary neighborhood.
Now, based on the latest data obtained by NASA’s SPHEREx Mission, the mystery of this strange distant space visitor has only deepened, offering compelling new observations to the emerging picture of what is currently known—and what remains mysterious—about 3I/ATLAS.
A Rare Visit From Beyond
Since its discovery, scientists have been eager to seize this rare opportunity to study a distant space object, which has already exhibited several unusual features related to its chemistry and potential origins.
Only the third interstellar object ever detected, the detection of 3I/ATLAS follows the discovery of ‘Oumuamua in 2017 and 2I/Borisov in 2019, both of which were also determined to be interstellar objects possessing some unique qualities.
Traveling at roughly 61 kilometers per second, the latest addition to our growing collection of observed interstellar visitors does not appear to be gravitationally bound to the Sun, and will eventually exit the solar system after a brief inner passage, during which its closest approach to Earth will occur later this year.
For now, astronomers are eager to use telescopes and spectroscopy to probe its makeup and glean insights into the conditions of distant planetary systems.
A Carbon-Rich Comet
Among the most compelling new findings related to 3I/ATLAS are those detailed in a recent study based on data collected from NASA’s SPHEREx and IRTF observations, which reveal that the unusual comet is doing something else that now has astronomers talking: it’s releasing large amounts of carbon dioxide.
Combined spectral features indicate that this likely originates from both water ice absorption and CO₂ gas emission, with 3I/ATLAS producing a bright carbon dioxide coma extending some three arcminutes across.
This is significant, since the preliminary upper limits on water and carbon monoxide output that such an object would be expected to produce suggest that the observed brightness of 3I/ATLAS probably comes almost entirely from its surrounding dust cloud rather than its core.
This means that, based on the currently available data, 3I/ATLAS is likely to be a carbon-rich comet, which offers some potentially important insights about the conditions in the environment where it originally formed well beyond the edges of our solar system.
So What is 3I/ATLAS?
3I/ATLAS draws its name from the Asteroid Terrestrial-impact Last Alert System (ATLAS), the telescope network that first discovered it (although it was later revealed that early astronomical imagery collected by the Vera C. Rubin Observatory also managed to photograph the object even earlier, although its existence was not recognized at that time). The “3I” designation simply indicates it as the third known interstellar object.
However, one aspect of the 3I/ATLAS mystery that has recently garnered attention in news headlines involves ongoing speculations that the object could potentially be of technological origin, a possibility proposed by Harvard astronomer Avi Loeb based on the object’s unusual characteristics, including its appearance and trajectory.
Still, most astronomers remain of the opinion that 3I/ATLAS is simply a comet of natural origin, although a very unusual one.
Why 3I/ATLAS Matters
Recently, Hubble Telescope images of 3I/ATLAS have revealed the comet’s hazy “coma,” a cloud of gas and dust produced around the object as sunlight warms its surface. This activity gives astronomers a unique opportunity to study molecules formed in a different star system.
Based on spectral signatures in optical data collected about 3I/ATLAS, astronomers can determine what materials are present around it and whether it is likely to have originated in a solar system similar to ours or perhaps one with completely different features.
Unlike periodic visitors such as Halley’s comet, 3I/ATLAS is following a hyperbolic orbit. It will sweep through the inner solar system between Mars and Earth’s orbit before passing within 210 million kilometers of the Sun later this year. At its closest approach to Earth, it will remain about 270 million kilometers away, although it will be obscured from direct view during its closest approach.
Some astronomers, like Con Stoitsis, the comet and meteor director at the Astronomical Society of Victoria, Australia, say that although we don’t know exactly where the object will end up once it emerges on the other side of the Sun following its closest approach, one thing is certain: that the object will eventually depart from our solar system and continue its journey through deep space.
Will We Ever Get a Clear View of 3I/ATLAS?
Although 3I/ATLAS is getting brighter as it gets closer to the Sun, the object will remain very faint if it becomes visible to the naked eye. However, skywatchers armed with reasonably powerful telescopes will likely be able to spot it, although it will appear more like a faint smudge in the sky than the epic interstellar object that has caused such a stir within the astronomical community.
Currently, the lingering questions continue to fascinate astronomers. With so few opportunities to observe interstellar objects, 3I/ATLAS marks the latest advancement in our ever-growing knowledge of the cosmos, and a fleeting but invaluable chance to compare the chemistry of distant star systems with our own.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.