A Harvard scientist tracking the interstellar visitor in our solar system has issued a warning about its move behind the sun on Tuesday.
The object, dubbed 3I/ATLAS, will be exactly on the opposite side of the sun relative to Earth, constituting a so-called 'solar-conjunction,' tomorrow, which Avi Loeb said would be 'an opportune time for technological action.'
Loeb explained that in space travel, the best time to speed up or slow down a spacecraft is when it's closest to a large object, since firing the engine at that point, known as the Oberth effect, gives the biggest change in speed.
'If 3I/ATLAS is a massive mothership, it will likely continue along its original gravitational path and ultimately exit the Solar system,' the professor shared in a Sunday blog post.
'In that case, the Oberth maneuver might apply to the mini-probes it releases at perihelion towards Solar system planets.'
3I/ATLAS will reach its best window for such Oberth maneuvers just eight days after it slips behind the sun, which will put it the closest to the sun at about 126 million miles away, he added.
While Loeb has floated the idea that 3I/ATLAS could be of extraterrestrial origin, NASA has long maintained that the object is simply a comet from a distant galaxy.
However, that conclusion has not stopped Loeb from calling for more data before the case is closed.
A Harvard scientist warned interstellar visitor could perform a 'technological action' eight days after moving behind the sun on Tuesday
'As of now, 3I/ATLAS appears most likely to be a natural comet,' Loeb shared on hist Medium post.
'But the remote possibility of an Oberth maneuver must be considered seriously as a black swan event with a small probability, because of its huge implications for humanity.'
The professor added that he has identified several anomalies that have suggested the object could be of alien origin.
The trajectory of 3I/ATLAS is aligned within five degrees of the ecliptic plane, which is the same plane in which the planets orbit the sun, he shared.
Unlike typical comets, it displayed a sunward jet, or anti-tail, that is not a mere optical illusion caused by viewing angle.
This stream of gas and dust is unusual because comet tails are typically pushed away from the sun by solar radiation and wind.
NASA's Hubble Space Telescope observed a similar phenomenon, capturing an extended glow aimed sunward in late July.
Loeb explained that the glow stretched roughly ten times longer than it was wide, forming what he described as the geometry of a jet directed at the sun—a pattern unlike any known comet.
The object is also far more massive than previous interstellar visitors, measuring about a million times heavier than 1I/'Oumuamua and a thousand times heavier than 2I/Borisov while moving even faster than both, he explained.
Loeb also highlighted 3I/ATALS' arrival timing, allowing it to pass within tens of millions of miles of Mars, Venus and Jupiter, yet remain unobservable from Earth at perihelion.
Spectral data further showed that the gas plume surrounding 3I/ATLAS contains much more nickel than iron, similar to industrially produced nickel alloys, with a nickel-to-cyanide ratio far exceeding that of any known comet.
Loeb noted that it also contains only four percent water by mass, a striking contrast to the water-rich makeup of ordinary comets.
Adding to the mystery, 3I/ATLAS exhibits extreme negative polarization, a property never before seen in any comet, and it entered the solar system from a direction within nine degrees of the famous 'Wow! Signal' detected by radio astronomers.
'Gladly, we expect to get data on 3I/ATLAS shortly after perihelion. On November 4, 2025, ESA's Jupiter Icy Moons Explorer (Juice) will pass within 40 million miles of 3I/ATLAS,' Loeb said.
'If 3I/ATLAS maintains a trajectory shaped by gravity alone, it will come closest to Earth on December 19, 2025, at a distance of 167 million miles.'
'On March 16, 2026, 3I/ATLAS will pass within 34 million miles of Jupiter and be observable to sensors in the UV, infrared, and radio bands onboard the Juno spacecraft.'