In new book, Harvard astronomer pushes theory about object that passed through solar system; alien world may have sent it

Avi Loeb, the chair of Harvard's Astronomy Department, pictured with the 15-inch telescope known as "The Great Refractor," which was installed in 1847. (Lane Turner/Globe Staff)Lane Turner/Globe Staff

Harvard astronomy professor Avi Loeb’s highly anticipated new book, “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth,” is being published Jan. 26, detailing his controversial theory that an artificial object may had been sent to Earth in 2017 from an extraterrestrial civilization.

The title’s being published by HMH Books, the company said in a statement, which highlighted a blurb from New York Times best selling author Alan Lightman calling “Extraterrestrial” provocative “and thrilling” and praising Loeb for asking readers to “think big and to expect the unexpected.”

In late 2017, the statement said, “scientists at a Hawaiian observatory glimpsed an object soaring through our inner solar system, moving so quickly that it could only have come from another star.” Loeb, the statement continued, “showed it was not an asteroid; it was moving too fast along a strange orbit, and left no trail of gas or debris in its wake. There was only one conceivable explanation: the object was a piece of advanced technology created by a distant alien civilization.”

The company added that Loeb takes readers inside “the thrilling story” of the first “interstellar visitor” to be spotted in our solar system.

“He outlines his controversial theory and its profound implications: for science, for religion, and for the future of our species and our planet,” the statement said. “A mind-bending journey through the furthest reaches of science, space-time, and the human imagination, Extraterrestrial challenges readers to aim for the stars—and to think critically about what’s out there, no matter how strange it seems.”

Loeb had discussed his research with the Globe in 2019.

He said he’d been thinking about the phenomenon of ‘Oumuamua, a mysterious object that hurtled close to Earth in 2017. It had become an instant sensation in the scientific community, the first known object from outside the solar system, and astronomers and astrophysicists had jumped to analyze and explain the anomalous object. Theories were developed. Papers were published.

Loeb had a theory, too, and in late 2018, he detailed it, along with coauthor and postdoctoral researcher Shmuel Bialy, in an article for The Astrophysical Journal Letters. Perhaps, he reasoned, the structure had been an artificial object sent from an extraterrestrial civilization.

Almost immediately, the piece ignited the kind of firestorm rarely, if ever, seen in the buttoned-down world of modern-day astronomy.

In the months following the paper’s publication, astrophysicists from across the country spoke out against Loeb’s theory, painting him as a sensationalist and worse. The researcher who first discovered ‘Oumuamua — Hawaiian for “messenger from afar arriving first” — via telescope called Loeb’s suggestions “wild speculation.” Another compared Loeb’s logic to that of flat-earthers.

But even as criticism continued to pour in, Loeb refused to back down, digging in his heels against what he considers unjust appraisal.

His work, he insisted in an interview last year, isn’t the result of some half-baked sci-fi fantasy; in fact, of the hundreds of papers he’s written during the course of a decades-long career — including some that have touched on the possibility of alien life — he does not consider this one to be among his most speculative.

In the case of ‘Oumuamua, Loeb said, he is simply using the available data to draw an evidence-based conclusion; namely, that the object — whatever it is — did not behave like it should have if it were a typical comet or asteroid.

If it were a comet, Loeb said, its excess acceleration would have likely been apparent in the form of a tail of dust or gas. Another anomaly? Its extreme shape, which is unlike any asteroid or comet observed before.

“Let’s put all the possibilities on the table,” Loeb said.

Part of the high-profile response, certainly, can be attributed to Loeb’s academic pedigree.

Irwin Shapiro, the former longtime director of the Harvard-Smithsonian Center for Astrophysics, called Loeb “brilliant.” Stephen Hawking once dined at his home. In 2012, Loeb was named one of the 25 most influential people in the field of space research by Time Magazine.

But there have been vocal critics too.

Rob Weryk, a planetary defense researcher at the University of Hawaii and the person who initially spotted ‘Oumuamua, said in an interview last year that there isn’t “any reason to believe that it’s anything but a natural object.” Paul M. Sutter, an astrophysicist at Ohio State University, went further, arguing that while Loeb’s paper itself is mostly harmless, the widespread attention it has received threatens to damage the field’s long-term credibility.

“Here’s yet another thing where people think that astronomers are just hunting for aliens,” said Sutter. “The next time we go out to Congress or the public asking for money, there’s going to be a lot of people shaking their heads saying, ‘Oh, you guys are just nutballs.’”

Loeb, though, stood firm last year in the face of continued criticism.

“If someone would show me evidence — a photograph of ‘Oumuamua, or clear evidence that it’s natural in origin — then I would admit it and move on,” he said at the time.

Until then, he said last year, he’s happy to serve as a kind of modern-day Carl Sagan — enduring a few welts in the name of existential progress.

“In the military, there is a saying: ‘If you’re a good soldier, you put your body on the barbed-wire so that others can pass over it,’” he told the Globe.

“I’m willing to put my body on the barbed wire.”

Material from prior Globe stories was used in this report.