… or should that be, “There’s no OTHER place like home… yet…”?
Exo-planets – or “extra-solar planets” to give them their full title – are currently the coolest things in astronomy. Following the launch of NASA’s exo-planet hunting Kepler telescope, many people are now getting very excited about the prospect of finding Earth-sized worlds Out There in the Black.
But many people aren’t.
I gave an Outreach talk the other week (see a previous post) and was asked about “that new spaceprobe that’s looking for another Earth”. I assumed they meant Kepler, so I briefly described its mission. The questioner looked strangely unimpressed, so I asked why. “Well,” they replied, “it doesn’t really matter, does it? Even if they find one it won’t affect us. Why are you so worked up about this?”
Hmmm. It’s a good question actually. Why DOES it matter that we now know some of those twinkling points of light in the night sky are circled by strange, exotic worlds? Why are astronomers spending hours and hours gazing at these distant suns, hoping to glimpse signs of planets spinning around them? And with countless problems to solve down here on Earth, why should money be spent on scanning the heavens for far-flung alien solar systems with multi-million $ telescopes, satellites and computers?
Simple. Because we have to leave Earth and find another home.
Not today, not this year, not anytime soon. Probably not for a thousand generations. But at some point, for some reason – global warming, catastrophic pollution, war – Mankind or at least some members of Mankind will have to leave Earth and set up another home Somewhere Out There. And although we don’t need to start planning that exodus or expedition just yet, as is true for any imminent long road trip it’s a good idea to actually have a destination chosen – a guaranteed distant gravel driveway to scrunch to a comforting halt on.
And the search for exoplanets is nothing less than the search for worlds where Mankind might one day make its home.
“Oh come on!” I can hear some of you laughing right now, possibly having terrifying flashbacks to the godawful TV series ‘Earth 2′, “that’s science fiction!” And that’s true – for now. Not just because we’re nowhere near the tech needed to build starships and launch them into deep space, and not just because the aforementioned threats of global warming, pollution and war could all be tackled if we put our minds to it, but because we haven’t actually FOUND any Earth 2′s yet. We have found no scrunchy gravel driveways to draw up on after a long journey.
As I write this on a deliciously crisp Spring Sunday morning in the Lakes, we know of 344 exoplanets, orbiting 291 stars. That’s an INCREDIBLE thing, an ASTOUNDING thing, an unbelievable paradigm shift from where we were just a decade ago. For most of my life I’ve looked up at, and lived beneath, a Cumbrian sky (hmmm, good name for a blog, that! ) strewn with diamond-dust stars, painted with flower petal nebulae and embroidered with filigree star clusters and galaxies. But the only planets in it were the ones of my own solar system. Now I can go out on a knife-sharp clear and frosty night, lift my tired eyes from the ground, and within moments find a star that has its own solar system. Even just thinking about that makes the hairs on the back of my neck stand on end..!
But not one – not one! – of the 344 planets we’ve found Out There is even remotely like Earth. In fact, mots are about as much like Earth as a blue whale is “like” a goldfish. Almost all the planets found so far are either freaks or fools. Many are huge bloated balls of gas, many times bigger than Jupiter, that whirl around their parent star so closely they’re almost surfing across its fiery surface. Others are smaller and more solid, but still bizarrely alien, disobedient, rebel worlds that are nothing like Earth either.
Why? Well, even the most sophisticated, cutting-edge exo-planet hunting technology and techniques we have are not advanced enough to detect Earth-sized worlds. We’re getting there, we can now find worlds several times bigger than Earth, but a true Terra-sized planet is still frustratingly beyond our grasp, and we’re limited – as amazing as it is – to finding “Super Earth” planets that aren’t much like our own.
Ah, but one day…
One day we will have the technology and the techniques to allow us to find Other Earths circling around Other Suns. One post-Kepler day we won’t just be able to detect them by measuring the way they make their parent stars wobble, or by measuring the tiny dip in their parent star’s brightness as the planet passes between it and us, but we’ll be able to image the planets themselves, take their pictures, and actually see them glinting like tiny sequins or shimmering fish scales in the almost blinding glare of their suns.
And when we’ve finally tracked down worlds the size of Earth we’ll develop even more advanced tech and techniques to let us look at them more closely. We’ll learn if they have atmospheres, oceans and forests of their own. We’ll eventually be able to see if they really are “like Earth”.
And on one magical, wonderful, amazing future day, a team of uncomfortable-looking scientists will sit on a stage , behind a long table, facing banks of cameras and a seething crowd of journalists, and grin as the US President, standing at a podium in front of them, announces to the world that they have finally, after centuries of searching by generations of astronomers, found Another Earth. He’ll ask for the huge screen behind them to show “Slide 1″ - a star map with one star circled in red, or gold, or perhaps, more fittingly, ocean blue, and then zoom in that star to show a tiny speck of light basking in its glow. Zooming in on it again they’ll make that point of light grow bigger still until it is a tiny, hazy, blurred disc, with columns and rows of figures next to it describing the constituents of its atmosphere, its surface temperature, its gravity… some reporters will see the words “nitrogen” and “oxygen” on the screen, and realise that they are the telltale signs of a habitable – and maybe even inhabited – world, and a buzz will start to grow…
More figures will flash up then, showing that the scientists’ instruments had detected methane, chlorine, chlorophyl, and more of the scientists will realise what it is they’re seeing: evidence of life…!
Then the real show-stopper – the blurred dot on the screen behind the scientists will grow larger and larger, its image will grow sharper and crisper, as if a lacey veil has been pulled away from in front of it, and there will be gasps as the journalists and the watching world see familiar sights – areas of achingly-beautiful blue inbetween areas of brown and gold… gleams of mother-of-pearl blue white will become visible at the top and bottom of the disc, while feathers and streamers of cream and white will appear over the planet’s land masses, dotted here and there with out of focus catherine wheel swirls of huge storm systems…
“Ladies and gentlemen,” the President will say, “this team of scientists, sitting behind me, has found another Earth.”
Imagine that… just imagine that… take a moment to think about what it will feel like to witness that moment in history. It will be unique in the most absolute sense of the world. There will only ever be one “first other Earth” found, only one announcement of its discovery – and we could be just a handful of years away from it.
And in the years, decades and centuris that follow, that world – and others found like it – will be studied intently until we are confident that they could support life. And then Mankind will know it has anoher place to go Out There.
And when the first great starship is built, as one day it will be, its destination will be one of the worlds detected by telescopes like Kepler – perhaps even one of the worlds found by Kepler itself.
That is why we’re looking for exo-planets. We have no choice. We can’t stay here, on this world, forever.
One day we’ll colonise the Moon, and Mars, and the satellites of Jupiter and Saturn, but our tennancy on those worlds will be limited by the lifetime of the Sun, and when the Sun dies so too will our solar system. So although the solar system is going to be our home for a long, long time, we need other homes Out There if we’re to ensure the survival of our species, its art, music and civilisation.
And it’s incredible to be alive in the years when we’ve started to look for those homes.
But there’s an even more profound reason for embarking upon this quest. We have this insatiable hunger to know if we’re Alone in the universe. If we find just one – just one – Earth-like world in a habitable zone around another star, then there’s a very good chance there’ll be some form of life on its surface. If we actually detect life – even plant life – on a planet orbiting another star then that is proof that the development of life is a process, not just a fluke restricted to Earth, and then there’s a very real possibility that we are part of a living universe, and share it with other races, other civilisations and other cultures. Searching for Earth-like worlds is searching for relations, or at least neighbours, in the Black.
That is why it matters.
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