The 43-day government shutdown didn’t only affect affairs on Earth, it also reached into space. While the feds idled, an interstellar object known as 3I/ATLAS was barnstorming the solar system, at a speed that reached 153,000 miles per hour as it tore past Mars, whipped around the sun, and headed on a trajectory that will take it back into deep space. It was only yesterday, with the government’s lights back on, that NASA released an album of images taken by at least 20 spacecraft and ground telescopes tracking the comet’s visit. It is just the third known rock from outside our solar system to pay us a call and NASA and the European Space Agency made the most of the opportunity to document it.
3I/ATLAS was discovered on July 1 by a NASA-funded telescope in Rio Hurtado, Chile known as ATLAS, for Asteroid Terrestrial-impact Last Alert System. The telescope is part of a cluster of four observatories that include two in Hawaii and one in South Africa, whose job is to do exactly what the Chile telescope did: scan the skies for interstellar ordnance that might be on a collision course with Earth. The good news is that 3I/ATLAS poses no danger; analysis of its trajectory shows that it will pass no closer than 168 million miles from our planet, on Dec. 19. The scary thought is that if it did hit us, it would pack a globe-rattling wallop. The comet measures somewhere between 1,400 ft. and 3.5 miles across—significantly wider than the island of Manhattan, which measures only 2.3 miles across at its greatest. (That is still a relative pipsqueak compared to the asteroid that wiped out the dinosaurs, which is believed to have measured up to nine miles across.)
This didn’t stop Loeb from publishing a new paper on Cornell University’s preprint site arXiv, making similar alien claims about 3I/ATLAS. “[I]n this paper,” Loeb and his co-authors wrote, “we present additional analysis into the astrodynamics of 3I/ATLAS, and hypothesize that this object could be technological, and possibly hostile.” They base their argument on the trajectory of the comet, “which approaches surprisingly close to Venus, Mars, and Jupiter,” and thus “allows the object access to our planet with relative impunity.”
Nonsense, say other experts. “It’s natural to wonder what it is. We love that the world wondered along with us,” said Nicola Fox, associate administrator of NASA’s Science Mission Directorate, at a news conference, as reported by Reuters and USA Today. “We were quick to be able to say, ‘Yup, it definitely behaves like a comet.’ We certainly haven’t seen any technosignatures or anything from it that would lead us to believe it was anything other than a comet.”
In another Reuters piece, University of Oxford astrophysicist Chris Lintott was blunter. “You might as well argue that the moon is made of cheese,” he said.
Heedless of all this chatter, 3I/ATLAS is taking its leave of us. The comet made its closest approach to the sun on Oct. 30, passing within 130 million miles of the solar fires. It will come our way shortly before Christmas, soar into the outer solar system a few months later, and pass back into the deep space reaches that birthed it billions of years ago. Earthlings who know where to look can spot it with a telescope in the pre-dawn skies, but most won’t take the trouble. Today’s sensation will, inevitably, vanish into the void.
