‘Oumuamua: Scientists will check the weird interstellar body for alien technology

Alan Martin November 21, 2017

‘Oumuamua – the oddball asteroid that is making us rethink everything we thought we knew about asteroids – is interesting enough to have scientists giving it a second longer look. The Green Bank telescope in West Virginia is set to listen for radio signals emanating from the device on the off chance it isn’t entirely natural.

“Most likely it is of natural origin, but because it is so peculiar, we would like to check if it has any sign of artificial origin, such as radio emissions,” explained Harvard University professor Avi Loeb. This won’t be a long project either – which is just as well given it’s moving more than twice as fast as New Horizons, our fastest ship. The test will begin Wednesday, and according to Loeb: “if we do detect a signal that appears artificial in origin, we’ll know immediately.”

Loeb insisted that the chances of detecting symbols are “very small” but that this shouldn’t prevent us from at least being open minded to the possibility. “It would be prudent just to check and look for signals. Even if we find an artefact that was left over and there are no signs of life on it, that would be the greatest thrill I can imagine having in my lifetime. It’s really one of the fundamental questions in science, perhaps the most fundamental: are we alone?”

The original explanation of why ‘Oumuamua is so fascinating continues below

I say, I say, I say. What’s long and red and been travelling for millions of years? ‘Oumuamua.

If you’re struggling to see the punchline in that, it’s because there isn’t one. ‘Oumuamua is an asteroid that briefly visited our solar system – but it’s not like any asteroid we’ve ever seen before. In fact, it’s so unlike anything we’ve seen before, that scientists initially believed it was a comet, thanks to its unusual shape – but this was quickly ruled out when researchers noted it didn’t behave anything like a comet.

In fact, it doesn’t look or behave like any space object we’ve encountered before. It’s about a quarter of a mile long and around 80 metres wide, making it cigar-shaped. It has a faint red colouration – likely the result of cosmic irradiation. Observed from Earth, ‘Oumuamua’s brightness seems to vary by a factor of ten, suggesting it spins on its axis every 7.3 hours. No other comet or asteroid in the solar system has had this variety in its brightness.

“This unusually big variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape,” explained Karen Meech from Hawaii’s Institute for Astronomy.
“We also found that it had a reddish colour, similar to objects in the outer Solar System, and confirmed that it is completely inert, without the faintest hint of dust around it.” That suggests it’s made of something dense – likely rock and metal – with no water or ice.

‘Oumuamua was first spotted by the Hawaiian Pan-STARRS1 telescope back on 19 October, hence its unusual name. It’s a Hawaiian word which “reflects the way this object is like a scout or messenger sent from the distant past to reach out to us” – it means ‘a messenger from afar arriving first.’

That grandiose name is entirely justified: this is an asteroid that has come from beyond our solar system – and possibly far beyond. Scientists’ initial calculations suggested that ‘Oumuamua came from Vega in the Lyra constellation, which seems entirely plausible until you realise that at the speed the asteroid is travelling (a nippy 85,700mph per hour as of yesterday), it would take around 300,000 years to get here – and Lyra wasn’t in that position 300,000 years ago. That means, with that trajectory, it’s likely been travelling through space for hundreds of millions of years.

That’s just one of the mysteries of ‘Oumuamua, though. Here’s another: until ‘Oumuamua came along, scientists believed that interstellar objects would behave like comets, not asteroids. As it appears this isn’t the case, the chances are that there are lots more interstellar rocks in the Solar System than we thought.

“For decades we’ve theorised that such interstellar objects are out there, and now – for the first time – we have direct evidence they exist,” said NASA astrophysicist Thomas Zurbuchen. “This history-making discovery is opening a new window to study formation of solar systems beyond our own.”

Well, you know what they say: interstellar objects are like buses – you wait decades for one to come along, and then you realise that thousands were in front of you all along.

“The presence of ‘Oumuamua suggests that previous estimates of the density of interstellar objects were pessimistically low,” the paper explains. In fact, another paper from the University of California estimates that there could be as many as 1,000 interstellar visitors arriving, and another 1,000 leaving our solar system every year – or one every three days.

So, what would happen if one of these were to hit Earth? It’s not entirely clear, but it doesn’t sound good – even couched in the cautious language of the scientific paper: “Impact from an interstellar object would be far more energetic than from a solar system object with similar mass, due to the larger impact speed.” Given how unprepared we are for a regular comet or asteroid, that’s not too reassuring.

‘Oumuamua is now speeding away through our solar system, and scientists will continue to track it as it leaves. It’s due to pass Jupiter in May 2018, and then Saturn in January 2019. After that, it’ll fade from view, and leave us forever.

But don’t be too down: if ‘Oumuamua has taught us anything, it’s that these interstellar visitors are actually all around us. With imminent improvements to our telescopes allowing us to see smaller, fainter objects, this is unlikely to be the last time we’re blown away by an interstellar visitor. Say hello, wave goodbye.