How to avoid interstellar doom!

The alien apocalypse is nearly upon us. Or at least it could be. That is to say, we have no evidence to suggest it isn’t.

They could well be on their way now. Right now. Tearing their way at ludicrous speeds towards our little blue gem, intent on domination and armed to the teeth. If they have teeth. Which they definitely will do…row upon row of razor sharp shards in their manifold mouths.  Never ones to scaremonger of course, but we must ask: who is worrying about this? Other than Independence Day era Will Smith – who, exactly, has got our back?

Well – never fear, there is a plan. And that plan is to hide. Not as spirited as the more gung-ho may have hoped for – but much more pragmatic surely? If/when those ruthless blood-curdlers arrive we can safely assume they’ll be more advanced than us. After all, they will have found us and managed to get here before we could do the same. Technology wise, we will be most definitely on the back foot. But how do you hide a whole planet? This can’t be a serious academic solution surely? Oh but it is. Two astronomers from Columbia University in New York – Professor David Kipping and Alex Teachey – have a theory of how we can pull the duvet over the Earth.

The key is to understand how we mere humans search for distant planets around other suns. The best method we currently have is based on observations from the spectacular Kepler telescope. Use it to look at a star long enough, and carefully enough, and – if it has orbiting planets – you should be able to spot a dip in its brightness as they pass in front of it. And it works too; NASA has identified around 1000 planets this way. Now, Kipping and Teachey think that if we can do it – so, surely, can the hordes of rampaging extra-terrestrials just looking for their next planetary notch. However, if we know the likely method they’ll use to find us, we can start to figure out how to beat it. And in a fantastic piece of astronomical sleight of hand, Kipping and Teachey think we should shine lasers into space to counteract our own planetary dip as the Earth passes in front of the Sun.

Seems logical. Not only that, the pair have the numbers to go with it. They say in a recent paper in Monthly Notices of the Royal Astronomical Society that we’d need an optical monochromatic laser array emitting a peak power of around 30 MW for about 10 hours per year. This would be just enough to change our characteristic transit signature if the sun was being watched through the alien version of the Kepler telescope. That would cover light in the visible spectrum, but, of course, we have to assume that those devious invaders will be looking at other wavelengths as well. In order to perform the same trick for all wavelengths we would not only need tuneable lasers, but a lot more power than would be practical.

Yet, that is not the end of the plan. There is a way around this. Rather than simply hiding – the trick is to play dead. If we could develop a laser that specifically cloaked the aspects of our planetary signature which suggested it was biologically active then the aliens would just get…well, bored. Kipping explains: “If we just cloaked out those biosignatures then another civilisation might detect our planet through a transit, everything would add up, but Earth would appear as a dead world and they’d soon lose interest.”

So perhaps the best defence is not, as the saying goes, offense but rather disinterest. And if all this sounds a little paranoid – not to say gloomy – then note that Kipping and Teachey are quick to point out that we could always use these techniques for the opposite; to reach out to intelligent life. If we over distort our signature they say, then far from a dull lifeless rock, Earth will stick out like a vibrant sore-thumb.

So, the ultimate method to remain galactically introverted or a way to attract attention like a baboon’s rump? Either way – we predict a potentially spectacular Hollywood movie script based on Kipping and Teachey’s work. Boys…get in there quick, if you don’t do it, Will Smith is bound to.