After publishing a paper a year ago that suggested an alien ship recently flew around our Sun, Loeb has had a whole lot of explaining to do, but as The Washington Post reports, he's taking criticism from the scientific community in stride. This was the first interstellar object astronomers ever spotted, though there may have been thousands which had gone unnoticed. Scientists caught sight of Oumuamua only when it was already on its way out of the neighborhood, after all. At the moment, it appeared reddish, long and thin, but it could have looked entirely different before it came under the radar.
Starting with that idea, the new paper compared Oumuamua to other faint but more mundane comets that astronomers have observed. And a comet's death is not a quiet process; instead, these comets experience a so-called outburst that triggers their disintegration.
Sekanina specifically pointed out the comet C/2017 S3 (Pan-STARRS) that came from the Oort Cloud, which surrounds our solar system.
Since publishing a highly controversial paper on the recent interstellar visitor to our solar system, writes Avi Selk in the Washington Post, Abraham Loeb, head of Harvard's astronomy department, "has run a almost nonstop media circuit, embracing the celebrity that comes from being perhaps the most academically distinguished alien civilization enthusiast of his time - the top Harvard astronomer who suspects technology from another solar system just showed up at our door".
He told the Washington Post that the object is long yet no more than one millimeter thick and that it's so light that sunlight is moving the object out of the solar system.
Loeb wrote with his colleague Shmuel Bialy in a journal Letters in November: "Considering an artificial origin, one possibility is that Oumuamua is a lightsail, floating in the space as a debris from an advanced technological equipment".
"Many people expected once there would be this publicity, I would back down", he said. 'If someone shows me evidence to the contrary, I will immediately back down.' That lack of evidence is part of the problem with much of the research efforts focused on Oumuamua.