Why Scientists are Baffled by 'Oumuamua's Flight Through Space

In a preprint paper published November 1 on arXiv, Harvard Institute for Theory and Computation researchers Shmuel Bialy, Ph.D., and Professor Abraham Loeb, Ph.D., give an explanation for ‘Oumuamua’s recent uptick in speed, which scientists had previously pointed out could not be due to gravity alone. But it’s what the tacked onto the end that has made worldwide news.

In their paper, Bialy and Loeb describe the possibility of solar radiation pressure — the idea that photons from the sun might have pushed ‘Oumuamua along — but sneak in a far more creative idea at the end: “Alternatively, a more exotic scenario is that ‘Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization.” These are all just hypotheses, of course, and Bialy and Loeb admit that the only way the origin and mechanical properties of ‘Oumuamua and other objects like it can be “deciphered” is to search for other objects like it in the future to find support.

Oumuamua is largely a mystery to us, but we are certain about a few of its characteristics, thanks to the NASA Pan-STARRS1 survey, which first detected its existence on October 19, 2017. As the NASA experts explain, Oumuamua’s speed and trajectory suggest it was flung here from a different solar system, making it our first known interstellar visitor. It’s exceptionally skinny, at roughly 40 meters (131 feet) wide, and its redness suggests it’s so old that it’s been irradiated over billions of years by many different suns. It didn’t pose any threat to Earth when it entered or when it left, but it was first detected by NASA’s Planetary Defense Coordination Office.

‘Oumuamua likely hails from what is known as a binary star system — or a pair of two stars orbiting a common center. In a March 2018 paper published in the journal Monthly Notices of the Royal Astronomical Society, Dr. Alan Jackson explains that these types of star systems are known to launch object, like ‘Oumuamua, into space.

“It’s really odd that the first object we would see from outside our system would be an asteroid, because a comet would be a lot easier to spot and the solar system ejects many more comets than asteroids,” Jackson, who is the lead author of the study, said in a statement released at the time.

‘Oumuamua is on its way out of our solar system, and it’s high-tailing its way out of here — perhaps with the help of solar radiation pressure, or maybe because of the accumulated effect of many gaseous jets bursting from its surface, like others have suggested. The “alien probe” theory, of course, has no evidence, only a lack of evidence that leaves the question open.

Jackson and his colleagues estimate that ‘Oumuamua was ejected from its binary system sometime during the formation of the solar system’s planets. That would make it older than Earth.

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