Feeds

Boffins: Earth will be habitable for only 1.75 BEEELLION more years

UK team floats method for picking exoplanets to study in search for the lair of ET

Business security measures using SSL

Unless we meddlesome humans – or our follow-on Earth inhabitants – muck up our planet with a nuclear holocaust, runaway greenhouse emissions, or some other ecological disaster, our 4.54-billion-year-old home should be habitable for at least the next 1.75 billion years.

Well, there's always the possibility of chance encounter with some wandering asteroid or a visit by hungry Kanamits bearing a copy of To Serve Man, but if habitability due to the sun's output and expansion are the only considerations, we've got plenty of time left on terra firma.

"The Earth seems to be habitable for perhaps 6.29 billion years (Gyr), but this is excluding the influence of humans and our pesky habit of pumping extra CO2 into the atmosphere," blogs Andrew Rushby of the University of East Anglia, lead author of a paper (PDF) published on Thursday in the journal Astrobiology entitled "Habitable Zone Lifetimes of Exoplanets around Main Sequence Stars".

Rushby takes pains in his blog post to explain that the true motivation and purpose of his paper was to explore methodologies for determining the habitability of exoplanets that share earthlike characteristics, and not to make "a definitive statement" about our check-out time from our comfortable digs on Hotel Earth.

"We are not" making such a statement, he writes. "Earth is [our] test, our standard, our control. In reality we only validated the model against other more complex models for the Earth, and came to similar conclusion."

The Reg gives a respectful nod to Rushby's intent – and to his observation that "the press machine is a rapid, yet inefficient beast" – but setting a terrestrial deadline is too attractive a headline to let pass unexploited. So sue us.

But to be fair, Rushby's paper is far richer than mere Earth lifecycle dating. In it, he takes into account a broad range of exoplanetary variables, and concludes that a number of candidates may have habitable lifetimes that far exceed that of Earth. For example, he notes that Gliese 581d "might be clement for 42 Gyr! A huge amount of time."

A planet with such a long habitable period would have plenty of time to evolve advanced life forms, Rushby reasons, "if we make the assumption that evolution by natural selection is a universal constant, operating in a similar way in potential exobiological systems as it does on Earth."

Rushby suggests that future exoplanetary investigations – "or SETI campaigns" – might do well to focus on such planets, since the evolution of intelligent life is likely not a simple, few-billion-year affair. In his paper, however, he rightly cautions that "This tendency to view evolution as a progression toward increasing biological complexity and intelligence likely stems from an anthropocentric bias."

That said, he also reasons that if we want to search for extraterrestrial intelligence, it would be wise to rigorously analyze planets that have been around for awhile for evidence of, for example, organisms that have altered their planet's biosignatures to such an extent that they could be detected across interstellar space, since those life forms would "undoubtedly require some level of complexity beyond that of simple replicating molecules."

So if we're going to study exoplanets in some detail, we could do worse than to use Rushby's habitable-zone lifetime filter. After all, we only have about 1.75 billion years left to finish the job. ®

Providing a secure and efficient Helpdesk

More from The Register

next story
PORTAL TO ELSEWHERE scried in small galaxy far, far away
Supermassive black hole dominates titchy star formation
Boffins say they've got Lithium batteries the wrong way around
Surprises at the nano-scale mean our ideas about how they charge could be all wrong
Edge Research Lab to tackle chilly LOHAN's final test flight
Our US allies to probe potential Vulture 2 servo freeze
Europe prepares to INVADE comet: Rosetta landing site chosen
No word yet on whether backup site is labelled 'K'
Bacon-related medical breakthrough wins Ig Nobel prize
Is there ANYTHING cured pork can't do?
Cracked it - Vulture 2 power podule fires servos for 4 HOURS
Pixhawk avionics juice issue sorted, onwards to Spaceport America
City hidden beneath England's Stonehenge had HUMAN ABATTOIR. And a pub
Boozed-up ancients drank beer before tearing corpses apart
prev story

Whitepapers

Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.
WIN a very cool portable ZX Spectrum
Win a one-off portable Spectrum built by legendary hardware hacker Ben Heck
Saudi Petroleum chooses Tegile storage solution
A storage solution that addresses company growth and performance for business-critical applications of caseware archive and search along with other key operational systems.
Protecting users from Firesheep and other Sidejacking attacks with SSL
Discussing the vulnerabilities inherent in Wi-Fi networks, and how using TLS/SSL for your entire site will assure security.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.