For over two months, astronomers have been closely following an interstellar object \u2014 dubbed 3I\/ATLAS \u2014 as it screams through the solar system at a breakneck speed.<\/p>\n
The unusual visitor was only the third object from beyond the solar system ever detected, following \u2018Oumuamua, which was discovered in 2017, and 2I\/Borisov in 2019.<\/p>\n
Researchers have been fascinated by the object, generally believed to be a comet, finding that it\u2019s made up of far more carbon dioxide<\/a> than expected.<\/p>\n Now, Harvard astrophysicist Avi Loeb, who has extensively examined<\/a> the possibility that 3I\/ATLAS is an\u00a0artifact from an advanced extraterrestrial civilization<\/a>, suggests that the object could be far more massive than previously thought.<\/p>\n By analyzing its trajectory, Loeb and his colleagues found that its \u201cnon-gravitational acceleration\u201d was \u201csmaller than 49 feet per day, squared,\u201d in a recent blog post<\/a>. We also know how much mass it was shedding in the form of gases and dust particles.<\/p>\n From this data, Loeb inferred that the \u201cmass of 3I\/ATLAS must be bigger than 33 billion tons.\u201d<\/p>\n \u201cConsequently, the diameter of its solid-density nucleus must be larger than [3.1 miles],\u201d he concluded, roughly at the very top of the range of current estimates<\/a>, based on Hubble Space Telescope observations.<\/p>\n It\u2019s a notable conclusion, considering that it would make 3I\/ATLAS \u201cthree to five orders of magnitude\u201d more massive than either \u2018Oumuamua and 2I\/Borisov, which measured roughly a quarter mile and 0.6 miles in length, respectively.<\/p>\n To Loeb, it\u2019s yet another confounding piece of evidence that highlights the object\u2019s sheer rarity, considering how few interstellar objects we\u2019ve detected so far.<\/p>\n \u201cGiven the limited reservoir of heavy elements, we should have discovered on the order of a hundred thousand interstellar objects on the 0.1-kilometer scale of 1I\/\u2019Oumuamua before finding 3I\/ATLAS, yet we only detected two interstellar objects previously,\u201d he wrote in his blog post.<\/p>\n Loeb has also pointed out that the object\u2019s highly unusual trajectory brings it suspiciously close to Jupiter, Mars, and Venus. In just over a week from now, 3I\/ATLAS will come within just 1.67 million miles of Mars\u2019 orbit<\/a> around the Sun, a \u201cremarkable fine-tuning\u201d of its path, the astronomer previously argued<\/a>.<\/p>\n The astrohysicist reiterated that it\u2019s an exceedingly rare and exciting opportunity to point the HiRISE camera attached to NASA\u2019s Mars Reconnaissance Orbiter at the unusual visitor to get a more detailed look \u2014 which could also allow us to confirm its actual size.<\/p>\n \u201cThe amount of sunlight reflected from the brightest pixel in the HiRISE image will constrain further the nucleus surface area for an assumed albedo value,\u201d Loeb wrote.<\/p>\n He even says there\u2019s still a glimmer of hope that 3I\/ATLAS was a piece of alien technology intentionally sent to us. If the HiRISE camera were to conclude that the object\u2019s core is \u201clarger than [3.1 miles], then an origin associated with the interstellar mass reservoir of rocky material will be untenable,\u201d Loeb argued.<\/p>\n \u201cIs 3I\/ATLAS an unusually massive comet with an unusual chemical composition on an unusually rare trajectory or alien technology?\u201d he concluded. \u201cIn both cases, the object could shed CO2 and H2O ices from material that collected on its frozen surface as it plowed through interplanetary and interstellar space.\u201d<\/p>\n \u201cWe should not decide about the nature of 3I\/ATLAS based on the chemical composition of its skin,\u201d Loeb added, \u201cfor the same reason that we should not judge a book by its cover.\u201d<\/p>\n