Astronomers are listening for alien signals from a weird object that's flying through the solar system

ESO/M. KornmesserArtist’s impression of ‘Oumuamua
  • Astronomers recently detected a strange, cigar-shaped object passing through the solar system.
  • Called ‘Oumuamua, it appears to be a metal-rich asteroid that comes from another star system.
  • Just in case alien transponders are on the surface, a project called Breakthrough Listen is using a radio telescope to scan it for extraterrestrial signals.
  • So far no signal has been found, but more observations are planned and it could take a while to analyse all of the data.

Astronomers have trained powerful radio telescopes on ‘Oumuamua, one of the more bizarre objects ever detected flying through the solar system.

Initially thought to be a comet but later identified as an asteroid, ‘Oumuamua (which means “scout” in Hawaiian) is a cigar-shaped, 750-by-115-foot object that recently zipped around the sun and is moving too fast to get captured by the star’s gravity. Based on ‘Oumuamua’s unusually hyperbolic path through space, astronomers say it’s perhaps the first interstellar object ever detected – in short, a space rock from a distant star system.

Breakthrough Listen, a non-profit research organisation that bills itself as “scientific program in search for evidence of technological life in the Universe,” is now scanning ‘Oumuamua for possible radio or other wireless signals.

No one really expects to hear such tell-tale signs of intelligent alien life, but the organisation says ‘Oumuamua is good practice for if and when another foreign object zips through our cosmic neighbourhood.

“‘Oumuamua’s presence within our solar system affords Breakthrough Listen an opportunity to reach unprecedented sensitivities to possible artificial transmitters and demonstrate our ability to track nearby, fast-moving objects,” Andrew Siemion, Director of Berkeley SETI Research Center and a Breakthrough Listen member, said in a press release. “Whether this object turns out to be artificial or natural, it’s a great target for [Breakthrough] Listen.”

A big yet brief interstellar voyager

Oumuamua orbit path space planets solar system wikipedianagualdesign and Tomruen/Wikipedia (CC BY-SA 4.0)The path of the object ‘Oumuamua through the solar system in 2017.

Researchers discovered ‘Oumuamua on October 18.

After further telescope observations, astronomers described it as an unusually oblong asteroid with dense, metal-rich rock. It also has a dark-red sheen – a colour it earned from billions of years of cosmic rays corroding organic molecules on its surface – and, while it zips through the solar system at more than 16 miles per second, is tumbling wildly, rather than rotating smoothly.

Breakthrough Listen began a first round of observations with the Green Bank Telescope in West Virginia at ‘Oumuamua on Wednesday afternoon. (The device “listens” in radiowaves, so observations at night aren’t required.)

During the first pass, the Green Bank Telescope aimed its antennas at ‘Oumuamua and listened to billions of wireless radio channels for two hours. According to Breakthrough Listen, this observation recorded a whopping 90 terabytes of raw data – enough to fill up 23 new top-of-the-line iMac Pro computers.

“So far, no signal was detected,” Avi Loeb, a physicist at Harvard University and a member of Breakthrough Listen’s leadership, told Business Insider on Thursday.

But all that data is still being processed by supercomputers to weed out Earth-based signals and hunt for probable alien signals. What’s more, this covered only one side of ‘Oumuamua – so the group has planned three more radio observations before the strange object leaves our solar system for good.

“During follow-up observations the coming week, we will do 3 more passes with each receiver to cover other phases of Oumumua’s [sic] rotation,” Siemion wrote in an email that Loeb forwarded to Business Insider.

As for that strange cigar shape, Loeb suspects there is a simple yet surprising explanation, though he emphasised his lack of a definitive answer.

“I am currently working on ideas for how to form a highly elongated shape for a rock through a natural process,” Loeb said. “One path is through spin of molten rock droplets (lava) that form in collision of rocky planets (similar to the collision that produced the moon out of the Earth). Another is through instabilities in dust forming environments.”

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