‘Oumuamua

By Thomas A.E. Hesketh

Our world changed on Oct. 19, 2017, when an object was discovered by astronomers at the University of Hawaii (UH), Hilo’s Manoa Institute for Astronomy (IfA). After initial detection of an unknown object moving against the relatively fixed backdrop of stars and galaxies set in deep space, according to Lee Billing’s article in Scientific American’s Oct. 26, 2017 issue, Rob Weryck, a postdoctoral researcher at the UH, re-checked the data obtained from the Panoramic Survey Telescope and Rapid Response System (Pan-STAARS1) Observatory located near the summit of Haleakala on the island of Maui. He then quickly contacted his advisor.

Weryk’s advisor, Richard Wainscot, made additional observations confirming the discovery and requested others in the world astronomical network to study the phenomena, including researchers at NASA’s Center for Near-Earth Object Studies located at the Jet Propulsion Laboratory in Pasadena, Calif., the NASA’s Spitzer Space Observatory, the United Kingdom Infrared Telescope, the Keck Telescope on Mauna Kea, the European Southern Observatory’s Very Large Telescope in Chile and the Gemini South telescopes in Chile and Hawaii, according to Physics World on Feb. 12.

According to the UH System News, IfA astronomers searched for a common name that would reflect Hawaii, the location of the space object’s discovery. After consultation with Hawaiian language experts, the space object was given the name “Oumuamua,” (pronounced O-MOO-ah-MOO-ah), meaning “scout or messenger from afar, arriving first” or, “a messenger from the distant past.”

Scientific American also reported that Weryck contacted IfA astrobiologist Karen J. Meech, who had a longstanding hope that an interstellar visitor might be discovered. Meech and her team confirmed the initial data and became leaders among the worldwide community of astronomers in broadcasting the discovery and encouraging attempts to gain as much information as possible before the object became too distant to observe effectively.

“All we can say right now is this is something that was tossed out of another star system,” said Meech. “Now we have a piece of another planetary system flying by Earth, flying through our solar system, that we briefly have a chance to study.” She described the event as, “…a brief visit from a red and extremely elongated interstellar asteroid,” in a 2017 article in the British journal Nature, one of the first scientific publications to discuss the object.

However, the classification of the object as an asteroid would be questioned. As conveyed by Meech in the Nature article, the unnamed space object was first tentatively identified as an asteroid, the most common type of solid object in our solar system, and given the initial designation “A/2017 U1” by the Hawaiian astronomers (“A” for “asteroid”). Yet, the object didn’t fit the profile of known asteroids. Popular Mechanics reported that ‘Oumuamua approached the Sun from above “…at a high inclination of about 122 degrees off the ecliptic of the solar system (the approximate plane upon which the planets orbit)” and at a high speed, “15.8 miles (25.5 kilometers per second or 56,880 mph).”

The new object didn’t show the characteristics of comets either. As Professor Avi Loeb stated in the March issue of Scientific American, “[It] does not look like at least 99.999 percent of the solar system’s comets,” suggesting our chances of having detected it in the first place with present-day telescopes were no better than a million to one. Indeed, the sighting was fortuitous, because the primary purpose of Pan-STAARS1, funded mostly by NASA, is to detect near-Earth objects that might pose a threat to Earth—not to detect interstellar visitors.

The classification of the object as “interstellar” was revolutionary. According to Nature, none of the 750,000 known asteroids and comets was thought to have originated outside the solar system. Before the appearance of ‘Oumuamua, our nearest known neighbors outside the solar system were the binary star system Alpha Centauri, and its neighbor, the relatively nearby Proxima Centauri—both about 4.22 light years away. No visual image has been captured showing detail other than a fast moving speck of light against the coal black of deep space. Artists’ conceptions of ‘Oumuamua are the best we have.

Collectively, astronomers have been able to estimate with some specificity ‘Oumuamua’s physical characteristics; it is not a total mystery. In Physics World, Andrew Glester summarizes astronomers’ observations, concluding ‘Oumuamua has a “highly irregular shape, unlike anything from our solar system,” and it is elongated, possibly cigar shaped. ‘Oumuamua tumbles or rotates every 7.3 hours, Glester continued, but exhibits a “speed and trajectory that suggests that it has been inside our solar system since around 1837.” It was either too far from us to reflect visible light or moving too fast while in the inner solar system for a photograph to be captured.

Glester reports that the object is “…dark red in colour, rich in metal and/or rock,” consistent with Kuiper belt objects exposed to cosmic radiation for millions of years. “Trajectory calculations also confirm that [‘Oumuamua] had come from interstellar space, with its origin likely to be somewhere in the constellation of Lyra—home of the fictional aliens in Carl Sagan’s novel ‘Contact,’ the possible alien in Gene Brewer’s novel ‘K-PAX’ and the Galactic Empire in Isaac Asimov’s ‘Foundation’ trilogy.”

Although ‘Oumuamua has departed the inner solar system, the legacy of its discovery remains in the popular press. “What’s especially fascinating is that people are still writing papers on it, even though we effectively got a couple of weeks of data with everyone trying, and then the HST and the Spitzer data went a little longer, but that’s it. And people are still writing papers,” notes Meech, in a 2018 Astronomy article. Meech also gave a TED Talk on June 27, 2018, “The Story of ‘Oumuamua, the First Visitor From Another Star System,” which had more than three million views, leading her to conclude, “Clearly, people are interested.”

The most positive response to The Voice’s investigation into public reaction to ‘Oumuamua came in a written interview on April 23 with BCC astronomy instructor Matthew O. Fillingim, who said, “Just a ‘yay for science.’ Even though this object was really small—less than the size of a pixel in our largest telescopes—we (mankind) were able to figure out a lot about what this object is (or isn’t). By following its path across the sky, with the knowledge of how gravity works, we were able to figure out where it came from and where it is going, and that it is not from our Solar System. We were able to figure out its size and shape and rotation rate and a general idea of its composition (rock or metal-rich rock—not comet-like) just from looking at light reflected from it. We have not observed any radio signals coming from it. The consensus among astronomers is that it is highly unlikely to be artificial. There is a lot we can know about this object and a lot we don’t/can’t know. It is the first object of its type observed. But, with any luck, it won’t be the last.”

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