One of the Largest Structures in the Universe --Harbors Two Giant Elliptical Galaxies at Its Center
Image of the Day: Spiral Red Giant Star Cloaks Hidden Companion

Habitable Earthlike Planets in the Milky Way May be a Billion-Plus Years Older



Habitable conditions on Earth will be possible for at least another 1.75 billion years – according to astrobiologists at the University of East Anglia. Findings published today in the journal Astrobiology reveal the habitable lifetime of planet Earth – based on our distance from the sun and temperatures at which it is possible for the planet to have liquid water.The amount of habitable time on a planet is very important because it tells us about the potential for the evolution of complex life – which is likely to require a longer period of habitable conditions. Looking at habitability metrics is useful because it allows us to investigate the potential for other planets to host life, and understand the stage that life may be at elsewhere in the galaxy.

To date, no true Earth analogue planet has been detected. But it is possible that there will be a habitable, Earth-like planet within 10 light-years, which is very close in astronomical terms. However reaching it would take hundreds of thousands of years with our current technology.

The research team looked to the stars for inspiration. Using recently discovered planets outside our solar system (exoplanets) as examples, they investigated the potential for these planets to host life. The research was led by Andrew Rushby, from UEA’s school of Environmental Sciences. He said: “We used the ‘habitable zone’ concept to make these estimates – this is the distance from a planet’s star at which temperatures are conducive to having liquid water on the surface.”

“We used stellar evolution models to estimate the end of a planet’s habitable lifetime by determining when it will no longer be in the habitable zone. We estimate that Earth will cease to be habitable somewhere between 1.75 and 3.25 billion years from now. After this point, Earth will be in the ‘hot zone’ of the sun, with temperatures so high that the seas would evaporate. We would see a catastrophic and terminal extinction event for all life.

“Of course conditions for humans and other complex life will become impossible much sooner – and this is being accelerated by anthropogenic climate change. Humans would be in trouble with even a small increase in temperature, and near the end only microbes in niche environments would be able to endure the heat.

“Looking back a similar amount of time, we know that there was cellular life on earth. We had insects 400 million years ago, dinosaurs 300 million years ago and flowering plants 130 million years ago. Anatomically modern humans have only been around for the last 200,000 years – so you can see it takes a really long time for intelligent life to develop.

“Of course, much of evolution is down to luck, so this isn’t concrete, but we know that complex, intelligent species like humans could not emerge after only a few million years because it took us 75 per cent of the entire habitable lifetime of this planet to evolve. We think it will probably be a similar story elsewhere.”

Almost 1,000 planets outside our solar system have been identified by astronomers. The research team looked at some of these as examples, and studied the evolving nature of planetary habitability over astronomical and geological time.

“Interestingly, not many other predictions based on the habitable zone alone were available, which is why we decided to work on a method for this. Other scientists have used complex models to make estimates for the Earth alone, but these are not suitable for applying to other planets.

“We compared Earth to eight planets which are currently in their habitable phase, including Mars. We found that planets orbiting smaller mass stars tend to have longer habitable zone lifetimes.

“One of the planets that we applied our model to is Kepler 22b, which has a habitable lifetime of 4.3 to 6.1 billion years. Even more surprising is Gliese 581d which has a massive habitable lifetime of between 42.4 to 54.7 billion years. This planet may be warm and pleasant for 10 times the entire time that our solar system has existed!

“To date, no true Earth analogue planet has been detected. But it is possible that there will be a habitable, Earth-like planet within 10 light-years, which is very close in astronomical terms. However reaching it would take hundreds of thousands of years with our current technology.

“If we ever needed to move to another planet, Mars is probably our best bet. It’s very close and will remain in the habitable zone until the end of the Sun’s lifetime - six billion years from now.”

Habitable Zone Lifetimes of Exoplanets around Main Sequence Stars’ by Andrew Rushby, Mark Claire, Hugh Osborne and Andrew Watson was published in the journal Astrobiology on Thursday, September 19, 2013.

The Daily Galaxy via University of East Anglia

Image credits:


Super interesting! We knew there were potentially habitable planets out there, but not how for how long. Great post!

you should add (like 20 times) every time you refer to life and habitable the concept of LIFE AS WE KNOW IT fgs...

Long before that we should have the technology to dismantle everything inside the orbit of Mars, and create habitats that can adjust their orbits to stay within a changing habitable zone. Of course space faring habitats require changes to the concept of habitable zone. For instance, it could refer to anywhere that sufficient solar energy is available. The concept as it stands assumes a non-technological environment.

An interesting implication: ecosystems that do not develop technologically advanced species are doomed to extinction. Mother Nature needs us after all.

Clear case to move to Mars at some point...need work on human developed magnetic field on Mars?!

its just a pity venus aint where mars is and vice versa!. There could be two equally habitable planets in our own solar system now!
Eventual migration to below the martian surface might be a good first step, followed by release of Co2 to help warm the place and increase pressure to regain its oceans. However, the other writer hit the are we going to maintain the atmosphere in the face of the current, let alone future sun, and how can we protect from radiation? A planet wide magnetic field may not prove a viable option!!!
Longer term, with current technology and some advancements, suggest that only generational space craft could be used to colonise distant worlds to ensure longevity of the human race beyond earth and solar lifetimes....A or B ark anyone??

Humans will have only roamed the planet earth for less than .00001% of its total existence. The window for human living conditions on planet earth are miniscule.

Would be a great shame to let the Sun die a natural death. If we take our role as Stewards of our Biosphere (equating to the habitable volume around the Sun) seriously, then we must embark on engineering the Sun to fuse its remaining fuel in a controlled fashion, rather than the obscene gluttony of the Red Giant phase. After the Main Sequence only ~10% of the Sun's mass will have been processed in the Core - the rest is frittered away during the Red Giant phase.

To tame the Sun, taking our cue from the work of David Criswell and Martin Beech, we must star-lift sufficient mass to keep the Sun's inexorable luminosity rise from becoming a runaway. If we time the mass-lifting to match the luminosity rise as the core's average metallicity goes up, then we can extend the Sun's useful lifespan several-fold - and make some new low-mass stars in the local neighbourhood from the excess mass.

Once the core is depleted, then we can look at using the degenerate core as a fusion reactor and trickle some of the H/He stockpile back to power it for a few more aeons. The trouble with standard biosphere computations is the assumption that Life won't or can't control the stars.

hubba bubba earth is the only place we can live...other places are at least 10 light years away.our whole generation would DIE before we reach'll take hundreds of thousands of years....unless NASA's going to build a huge spaceship and have people constantly making babies on that ship until someones baby finally reaches the other planets,there's no way we'll get there....I'm sorry if i sound pessimistic but theses ARE the facts

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.


Post a comment

Your Information

(Name is required. Email address will not be displayed with the comment.)