Nov 22, 2017 I Paul Seaburn

Interstellar Object Named but Shape and Source Still a Mystery

“A messenger from afar arriving first.”

While “What the heck is THAT?” might have been the first name considered for it, the first known interstellar object to be identified has now officially been named ‘Oumuamua, a Hawaiian word meaning “a messenger from afar arriving first.” While that seems to be more appropriate at first glance, at second glance “Mysterious spinning cigar from parts unknown” might be more appropriate.

New data released by the European Southern Observatory this week in the journal Nature sheds more light on the dark object discovered on October 19 by Rob Weryk, a postdoctoral researcher at the University of Hawaii Institute for Astronomy, using the Pan-STARRS1 telescope.

“I’d never expected to find something like this.”

On October 26th, Weryk and his fellow astronomers announced the discovery of A/2017 U1, along with the astonishing news that its behavior appeared to prove it was from outside of our solar system. While it was first believed to be a comet, subsequent analysis by the European Southern Observatory shows it’s behavior and composition to be more asteroidal.

Asteroidal, yes, but its shape says cigar-ish. (ESO photo here)

“Light-curve observations indicate that the object has an extreme oblong shape, with a 10:1 axis ratio and a mean radius of 102±4 m, assuming an albedo of 0.04. Very few objects in our Solar System have such an extreme light curve.”

cigar 640x425
For those unfamiliar with cigars

‘Oumuamua measures about 400 meters (1,300ft) long and 40 meters (130ft) wide, and spins rapidly like a spiraling football (American), making a complete rotation every seven hours. That shape and spin, along with its deep reddish color and carbon-based composition, make ‘Oumuamua one of the darkest space objects ever seen, absorbing 96% of the light that hits it.

That lack of reflective light may be the reason why it’s the first interstellar object to be discovered. However, it’s probably not the only one. Another study, led by David Jewitt at the University of California Los Angeles, estimated there may be up to 10,000 of them just between Neptune and the Sun, making their way through to … where?

Who knows? It might help if we knew where ‘Oumuamua came from, but all the announcement said was that it appeared to travel from the direction of the star Vega. The ESO shoots down that silly notion in a diplomatic and astronomical way:

“However, even travelling at a breakneck speed of about 95 000 kilometres/hour, it took so long for the interstellar object to make the journey to our Solar System that Vega was not near that position when the asteroid was there about 300 000 years ago. `Oumuamua may well have been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with the Solar System.”

An unattached happy wanderer. Sounds like ‘Oumuamua is living the good life … spearing through space from star to star with no cares or responsibilities. Too bad we couldn’t have spent more time with it. In an interview in The Atlantic, Andy Rivkin, a planetary astronomer at Johns Hopkins University, puts it best:

“Don’t be sad that it’s over. Be happy that you saw it. Because it is really amazing that we saw it.”

In other words, val da ri.

Paul Seaburn

Paul Seaburn is the editor at Mysterious Universe and its most prolific writer. He’s written for TV shows such as "The Tonight Show", "Politically Incorrect" and an award-winning children’s program. He's been published in “The New York Times" and "Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. His “What in the World!” podcast is a fun look at the latest weird and paranormal news, strange sports stories and odd trivia. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn't always have to be serious.

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