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Thursday 23 November 2017

Did Earth just get buzzed by an alien starship?

If it was one of these then we're all in trouble.

To answer the question in the title....No. 

Well. Almost certainly no.

But hang on, I should fill in the back-story here.... the object causing all this fuss is pretty odd. Called 'Oumuamua' it's (we think) an asteroid... although it's probably the weirdest, most scientifically compelling, asteroid we've ever found. 

Oumuamua was spotted in mid October of 2017. At first it was a fairly unremarkable spot of light: Probably some small, dim comet that no-one had ever picked up on before, was what most astronomers thought. 

Then they plotted its course backwards, to see where it had originated from: Oumuamua came from outside our solar system - from interstellar space. And, if it came from outside our solar system then it was, originally, a piece of another star system. No-one has ever seen such an object before - a natural interstellar traveller. Computer simulations have tentatively suggested that about one such object should pass through our solar system every year, but to actually spot one was like actually filming a Sasquatch - a mythic beast, captured on film.  

Above: The course Oumuamua took through our solar system, passing right by Earth.

The weirdness then got weirder, turning from " minor but historic discovery" to "whoa.. what?". Firstly this asteroid had, as you can see in the video above, swung relatively close by Earth. That's interesting, but maybe not very surprising - if it hadn't been in our neighbourhood we might well have never spotted it. 
But its shape is what has got everyone's heads a-scratching: Asteroids and comets range from potato to ball shaped. But Oumuamua is a stick shape: Ten times as long (about 800 meters long) as it is wide. 

Sasquatch has sprouted a third leg, and wings.*  

Above: The odd shape of Oumuamua. 

The colour of the asteroid (which can be broken down to reveal clues to it's surface composition) is reddish. that implies the surface is covered in the same kind of organic molecules - the same kind implicated in the origin of early life on Earth - that we see on the surface of comets. But, unlike a comet, this object has no trace of vapour coming from it, or of any ice. That suggests it's a rocky or metallic object beneath the organics... but how that squares with its strange shape, extreme origin point, is anyone's guess. 

So we get to the crux of the question: This looks like no natural object we've ever seen. So could it be an artificial one? it's extremely unlikely. At present there is no news of any heat signature, radio or microwave emissions, or other behaviour suggesting technology. Its speed, whilst very high (26 km/ sec) is still very slow for an interstellar probe - although that is assuming any probe building aliens would have similar life spans to ours (and there's no reason to assume that really, they could live much longer and be much more patient). 

But none of that is confirmation of a natural origin either - and while that's the most likely scenario by a long way, it must still be a spectacularly unusual natural origin to have produced such a strange object. That means it could a be a window into some truly alien geological processes, happening far, far across the universe from us.... Not aliens, but very, very alien natural processes. For that reason the astronomical community is gathering all the information it can on this object, before it disappears beyond the range of our telescopes. And, just in case, Centauri dreams website reports that SETI (Search for Extra Terrestrial Intelligence) and Breakthrough Listen organisations are/have been keeping Oumuamua under observation. 

As they say, watch this space.... 

UPDATE: To make things even more interesting a mission to hunt down and examine Oumuamua (or any other interstellar asteroids) is being proposed - some details here.

Sunday 12 November 2017

The Universe in 101 words: Will we return to Saturn's moon Enceladus?

Above: Enceladus, an ocean world covered in ice.

Our solar system is awash* with ocean worlds. And thanks to the Cassini missionary we've gotten to know one, Enceladus a 500km wide moon of Saturn, really well.

So what's it ocean like?

Dark - the ocean's covered in 20km of ice - but maybe not totally black: There's volcanic activity on the ocean floor, possibly like the white smoker vents of Earth, so there'd be the dim carmine glow of volcanism. More importantly the salty, alkaline, water contains organic chemicals and hydrogen - food for possible micro-life.

Cassini's mission is over - but its now hard to imagine us not returning to Enceladus....


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Above: The geysers of Enceladus, backlit: The ocean is literally leaking into space!