3 days ago
How To Find Planet B, And Get There Alive
Earth will have a meltdown. What are our options?
Tardigrades are little critters that were around before dinosaurs, and will eventually outlast us on Earth. They are so tough they can survive exposure to -272°C (cooler than liquid helium) and 150°C, which is quite a bit hotter than your pressure cooker. And Earth will be hotter than that in a few hundred million years – not entirely because of your car's tailpipe emissions. As our Sun grows older, it will expand, making Earth hot like Venus with its middle-age spread. So, we should start planning our escape now. But where can we go?
Lisa Kaltenegger's book Alien Earths has useful pointers for wannabe galactic hitchhikers. As the founding director of Carl Sagan Institute at Cornell University, Kaltenegger is an authority, but she's got no recommendations, yet. Ideally, you wouldn't want to travel too far because you are – as The Matrix's Agent Jones put it – 'only human'. How long will you live – 100, 120 years? Unless you hit Star Trek's fantastical 'warp speed' – faster than light – you can't go far in that time. Voyagers 1 & 2 left Earth in 1977, and they won't get close to another star for 40,000 years. So, space travel's a bummer. Besides, space is mostly empty. Looking out the window will mean death by boredom. Step on the gas, and a 1mg speck of space dust could destroy your ship.
So, speed and time are not on your side. Worse, your choice of space rock is a gamble. You have chosen it based on signs like the signature of its light, which tells you something about temperature on the planet's surface and the materials you'll find on it. Say, everything's perfect, and this planet circles our Sun's nearest neighbour, Proxima Centauri, which is about 40tn km away. You gather bag, baggage, family, and everything else that Moses took, and set sail on your ark. But…that light signal from Proxima took four years to reach Earth. Your data was already four years old. By the time you get there – cryofrozen, probably – in, say, 40,000 years, that planet may have ceased to exist. What then?
The choice of your future home is complicated by other factors also, Kaltenegger shows. Maybe you're looking too hard for an Earth-like planet and missing some gems. You want oxygen? Earth had precious little in its atmosphere till cyanobacteria appeared over 2bn years ago. They could split water, use hydrogen and free up oxygen. That's how oxygen increased in air. If Earth formed at 12am, atmospheric oxygen touched 15% concentration only at 10pm. And now, a few seconds before midnight, it's at 21%.
So, by looking for ready oxygen, you might miss some good candidate planets. Likewise, searching only for a planet with green plants might be a mistake. Plants on Earth are green because sunlight is strong and they absorb its red and violet wavelengths, while reflecting the green. But on a liveable planet around a red star – whose light has less energy – plants may need to absorb all the available light. Hence, their leaves could appear black!
Our next 'Earth' will definitely need some getting used to. There's so much to figure out and fix. But we can't do that if we make this Earth unlivable in the next decade or two. Have you checked your car's tailpipe emissions?
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Views expressed above are the author's own.
