NASA releases images of comet 3I/ATLAS, rejects alien spacecraft 'rumors'

3I/ATLAS is only the third interstellar object ever observed by astronomers traveling through the solar system. The others were comets called 1I/'Oumuamua (pronounced oh-MOO-uh-MOO-uh), detected in 2017, and 2I/Borisov, discovered in 2019.

Comets are small solid celestial bodies that are a combination of rocky and icy material that evaporates as they warm when getting close to a star like our sun.

3I/ATLAS has attracted particular attention because of one scientist's suggestion that it is not a comet but rather alien technology due to its trajectory, composition and other factors.

At the outset of Wednesday's briefing, NASA Associate Administrator Amit Kshatriya said, "To start with, I'd like to address the rumors" about the nature of 3I/ATLAS.

"I think it's important that we talk about that. This object is a comet," Kshatriya said. "It looks and behaves like a comet. And all evidence points to it being a comet."

Kshatriya noted that NASA missions are actively searching for signs of possible life beyond Earth, pointing to research published in September showing that a sample obtained by NASA's Perseverance rover of rock formed billions of years ago from sediment on the bottom of a lake contains potential signs of ancient microbial life on Mars.

"We want very much to find signs of life in the universe," Kshatriya said.

NASA said 3I/ATLAS poses no threat to Earth and will get no closer than about 170 million miles (275 million km) to our planet.

NEW IMAGES

Fox said NASA has studied 3I/ATLAS with more than a dozen scientific platforms including the Hubble and James Webb space telescopes and satellites orbiting Mars.

The new NASA images, all taken from afar, showed it with a blurry appearance but with the clear presence of a telltale coma - the hazy cloud of gas and dust around its nucleus - and the tail of dust following its orbit. The release of the images had been delayed by the U.S. government shutdown.

Tom Statler, lead NASA scientist for solar system small bodies, said the size of the comet's nucleus is hard to pin down, but estimated it based on Hubble observations to be in the range of "a couple of thousand feet to a couple of miles" in diameter. Statler said the nucleus seems to be "not very far from being round."

While the comet's precise point of origin remains unclear, the NASA scientists said they believe it hails from a solar system older than our own, which formed about 4.5 billion years ago. The scientists also said its composition differs in some ways from comets from our own solar system, as might be expected because it formed in a solar system that may have a different makeup than ours.

Astronomers around the world have intensively studied 3I/ATLAS.

University of Oxford astrophysicist Chris Lintott told Reuters: "So far, it seems to be made of the same sort of stuff we see for comets in our solar system - plenty of carbon dioxide and some water, carbon monoxide and other such molecules. We've also seen cyanide - normal for a comet - and lots of nickel, which is a bit surprising but not too unprecedented. We saw similar things in a previous interstellar comet, 2I/Borisov, and in some solar system comets."

"The idea that 3I/ATLAS could be an alien spacecraft is simply nonsense. There's nothing about it that suggests such a thing, and you might as well argue that the moon is made of cheese," Lintott said.

3I/ATLAS is now on its way out of the solar system, according to University of Hawaii astronomer Larry Denneau, co-principal investigator for ATLAS. Its closest approach to the sun came in October, and its closest approach to the Earth will come in about a month, Denneau said.