Oumuamua: Why the fuss about giant interstellar space rock?

in a tizzy over the passing through our solar system of what is said to be the first definitely proven inter-stellar object. Well, the first that anyone’s admitting to …

It was discovered on October 19 by researcher Robert Werryk at the Panoramic Survey Telescope and Rapid Response System, or Pan-STARRS, in the Haleakala Observatory in Kula, Hawaii, and was first given the codename A/2017 U1, which changed to 1l/2017 U1 largely because no one knew if it was a comet or asteroid – the code means first interstellar object of 2017 of unidentified origin.

Thankfully, the finding team decided on a nicer moniker and called it Oumuamua, meaning “messenger from afar” or “scout” in Hawaiian.

The far-travelled rock is believed to have come from

a star system elsewhere in our galaxy. It’s slightly less than 400m long and looks like a giant red-grey cigar.

SO WHAT’S THE BIG DEAL?

EVEN when it was found, Oumuamua was already speeding away from the sun and quickly fading from view. Scientists had just two weeks to aim their telescopes and pick up its first reflected light before the interstellar visitor got too far away. They looked for a “coma”, that tell-tale stream of evaporated particles that surrounds comets as they pass near the sun and their icy contents become heated.

That was the first of many unexpected things about Oumuamua – there was no coma, no tail and no obvious orbit.

Unlike comets and asteroids from our own solar system, Oumuamua is not in a regular orbit around our sun but has come crashing into the solar system from far outer space. It was not spotted until it would have been too late to do anything about it had the rocky body been heading for Earth. Uniquely, it is 10 times longer than it is broad.

It had actually raced over and through Earth’s orbit towards the sun when it was spotted and was tracked passing between Mercury and the sun before shooting away – at one point it reached a speed of 194,000mph – towards the outer reaches of the solar system and presumably off into deep space. Or maybe it’s just going home.

NOT YOU USUAL SPACE VISITOR THEN?

THE sheer oddity of Oumuamua was what really got the boffins. The hugely respected award-winning American astronomer Karen Meech – she has an asteroid named after her – explaine its differences.

One of the discovery team, Meech said: “Oumuamua varies in brightness by a factor of 10 as it spins on its axis every 7.3 hours. No known asteroid or comet from our solar system varies so widely in brightness, with such a large ratio between length and width.

“The most elongated objects we have seen to date are no more than three times longer than they are wide.

“This unusually big variation in brightness means that the object is highly elongated: about 10 times as long as it is wide, with a complex, convoluted shape.

“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.”

These properties suggest that Oumuamua is dense, composed of rock and possibly metals, has no water or ice, and that its surface was reddened due to the effects of irradiation from cosmic rays over hundreds of millions of years.

A CLOSE MISS?

IN terms of the vast distances in space, Oumuamua came perilously close to our little planet, its nearest position being about 15 million miles from us, or around 60 times the distance from Earth to the moon.

That being said, it never at any time came close to either us

or our sole satellite, so even though all those telescopes out there looking for objects that might hit Earth missed Oumuamua, we were all safe.

SO WHY THE HEADLINES?

WHAT has really excited scientists in the last 36 hours is the discovery that, unlike comets or asteroids that we normally see, Oumuamua appears to be covered in some kind of protective coating.

Its nature has not yet been established but it is thought to be carbon-based.

Significantly, though, some of the world’s top telescopes were trained on it for at least a fortnight, no matter came flying off Oumuamua, unlike the tail of a comet or the debris of an asteroid. This fact and the unusual shape of the asteroid of led to speculation that Oumuamua might be some sort of alien spaceship.

AN ALIEN SPACESHIP?

IN the absence of facts, the human imagination will always run riot, but the idea of there being a spaceship that just happens to look like a large lump of rock is fanciful at best. Nor is there any chance of sentient life on board as Oumuamua is estimated to be tens of millions of years old.

It has been apparently wandering in space all that time, a “rogue” asteroid that hasn’t hit anything.

WHERE DID IT COME FROM AND WHERE IS IT GOING?

BEST estimates are that it came from the approximate direction of the bright star Vega, in the northern constellation of Lyra.

But Nasa points out that “it took so long for the interstellar object to make the journey – even at the speed of about 59,000mph or 26.4km per second – that Vega was not near that position when the asteroid was there about 300,000 years.”

The Hubble space telescope tracked it doing 87,500mph and, having raced through Mars’s orbit last month, it will pass Jupiter’s in May nest year. It will travel beyond Saturn’s orbit in January 2019 and will not hit any of our neighbouring planets as it is travelling

20 degrees above the plane of their orbits. In about 20,000 years’ time, it will exit our solar system and head off across inter-stellar space again, apparently heading for a star or star in the constellation Pegasus.

SHOULDN’T WE HAVE VISITED IT JUST IN CASE OF ALIEN LIFE?

SADLY, it was and is going far too fast for any spacecraft from Earth to catch it. The best we can do is to monitor it and see if it is sending out any signals – and believe it or not, somebody is doing just that.

Russian billionaire Yuri Milner is the man behind Breakthrough Listen, the search for intelligent extra-terrestrial life which is costing $100 million.

He and his high-powered team decided to use their Green Bank radio telescope in West Virginia – the world’s largest of its kind – and started “listening” to Oumuamua earlier this week.

So far there’s been no signal activity from Oumuamua, but such is the power of Green Bank, if anything does emanate from the asteroid, they are confident of finding such data within days.

SO WHY DID EVERYONE GET SO EXCITED?

THOMAS Zurbuchen, associate administrator for Nasa’s science mission directorate in Washington, summed it up: “For decades we’ve theorised that such interstellar objects are out there, and now – for the first time – we have direct evidence they exist.”

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