Worldwide Change in Blue Whale's Song Baffles Scientists
The "METI (Message Extra-Terrestrial Intelligences) Debate - A Weekend Classic

The Planets of Alpha Centauri: The Hunt for a Pandora


James Cameron’s new movie Avatar depicts a gas giant with a habitable moon, Pandora, around it. Could there be real habitable planets orbiting among the three stars of the Alpha Centauri system? What are the odds that a "Pandora," really exists? 
With the diminishing odds that our solar system supports advanced forms of life, the nearest stars become ever more attractive candidates for discovery. And among the stars with possible habitable planets is the Alpha Centauri triple star system, the closest star system at only 4.37 light years from our Sun, which hangs above the horizon of Saturn in the image above. Both Alpha Centauri A and B -- stars very similar to our own Sun -- are clearly distinguishable in the image. (The third star in the Alpha Centauri system, the red dwarf Proxima Centauri, is not visible here.)
From the orbit of Saturn, light (as well as Cassini's radio signal) takes a little more than an hour travel to Earth. The distance to Alpha Centauri is so great that light from these stars takes more than four years to reach our Solar System. Thus, although Saturn seems a distant frontier, the nearest star is almost 30,000 times farther away.
The image was taken in visible red light with the Cassini spacecraft narrow-angle camera on May 17, 2008. The view was obtained at a distance of approximately 534,000 kilometers (332,000 miles) from Saturn. Image scale on Saturn is about 3 kilometers (2 miles) per pixel.

While Cameron was creating a fictional moon orbiting a gas giant circling Alpha Centauri A, several very real astronomers have focused in on Alpha Centauri as a potential zone for Earthlike planets. Professor Debra Fischer of Yale University, currently working at the Cerro Tololo Inter-American Observatory (CTIO) in Chile, is aiming the CTIO 1.5 meter telescope at both Alpha Centauri “A” and “B” as a part of a 5 year observation that will hopefully reveal planets as small as Mars.

Fisher is using the radial velocity method, which uses spectral measurements to detect variations in the speed that a star moves towards or away from Earth (any star with planets will move in its own small orbit around a common center of gravity).

In addition to Fischer’search, Michel Mayor’s team at the La Silla Southern Sky extrasolar Planet search Programme, is using instruments sensitive enough to detect a Centauri planet down to Mars size, depending on the stability of the stellar atmospheres. We may well find one or more small, rocky worlds, at which point the question becomes whether or not such a planet could have oceans — we don’t know what close binaries may do to water delivery from asteroids and comets. Whatever the case, though, a Centauri planet in the habitable zone would be a potent stimulus to earth-bound human imagination and an obvious target for interstellar probes of the future.

To the two ongoing hunts for planets around the Alpha Centauri stars the Centauri Dreams blog reports that we can now add a third. John Hearnshaw (University of Canterbury, Christchurch) reports that the university’s Mt. John Observatory has begun a program to search for Earth-mass planets around Centauri A and B. Although the observatory is heavily invested in microlensing technologies, the new efforts will put radial velocity methods to work using the Hercules spectrograph.

Casey Kazan



Excellent idea to closely scrutinize that star system.

Two other tasks need to be done.

1) determine the phase those stars are in, that is, will they last longer than our Sun before expanding out to engulf planets near them (the Sun will expand out to Mars); if they won't last longer then they cannot be a long term home world

2) increase our space travel technology quality; it would take is up to 75,000 years to get there ONE WAY at our current space craft speeds (e.g. Voyager I, II travel at 30,000 - 38,000 mph)

Good article.

it is clear that we cannot travel to the nearest stars. 20000 to 50000 years is too much for us to bear.may be it will suit us if the stars come much closer to us !! seems even the milky way is impossible for us to navigate about.why not try to seek help from the ufos and aliens ?

With the time scales involved what 'phase' the stars are in doesn't matter (as long as it's not tomorrow:) But our sun is good for another 3 billion years or so, likely the same for any of the three Centauri stars. The bigger problem, as you point out, is travel time. I think we could improve on those speeds and times considerably but it will still take hundreds, and maybe still thousands of years. One thing is for sure, we must expand off Earth. First LEO, the Moon, Asteroids, Mars, then a leap out to the outer solar system, Ort cloud, which by that time we're almost halfway to the next star anyway!


"our sun is good for another 3 billion years or so"

Good for what? The earth will be fatally disrupted long before it expands all the way out to our orbit during its demise, and we do not know when that will happen.

Catastrophic disruptions (to our ecosystem) will happen even before that, as solar storms become intense.

Recent observations show that our star models as to when they fail have been brought into question recently by stellar explosions well before (billion years) they should have happened.

We may be wise to try to have space travel to another home world fine tuned in a million years.

If we haven't found a way off this rock in a million years, I'll be really disappointed.

3 Billion is a number pulled from memory. Doing a quick check at a few astronomy sites ... it's more like 5 to 10 billion, but why quibble. I just meant to convey it's a long friggin time away and to worry if the Centauri star system will last sufficiently longer than ours to make it worth the effort of turning it into a second home for mankind. First we have to get off this rock and actually live somewhere else. Second since no species has lasted more than a few millions of years we should also attend to assuring humans last long enough see a star burn out. Third, if either Sol or any Centauri star goes nova it'll hardly matter how much longer the other star last afterwards since hard radiation, shock wave, a very bright light! and other things will kill all life on, in, and near Earth, blow away the atmosphere, vaporize the oceans, carbonize what's left. Fourth, as Pip suggests, Man has got to be gone or going a LOOOOOONG time before then or a million years from now. That's a generous number, if we aren't going, as in, living all over the inner system in a 100 years, we have a big problem as a species. We will live and die on this planet and it will be sooner than later. We can not stay on this planet, if for no other reason then what happened to the dino's will eventually happen to us. One planet, one rock, end of story. Of course this is the part we agree on 100% .. Let Go !!

Spoken like a true Washingtonian ...

"what ... me worry?"

let my kids worry about it ...

Agreed with James comment.

Dredd does NOT seem to NOT understand what the article is talking about.

Another point : should either one of Alpha A or Alpha B decide it is time for her to die it will never become a Supernova (matter of Mass) however it is better to not be present to that death.
Both are vey nearby to Sol.

Regards to possible abitable planets or moons in the Apha Centauri system.

For the time being, TIME would appear to be working against us.

To put it plainly & simply, if we put the remnants of humanity, plus plants, animals, everything needed to keep an eco - system going on a ginormous multi generational space - craft in attempt to colonize an Earth - like world & preserve human / Terran life, & it arrives to find one of the stars of the Alpha Centauri system changing to where the planets are uninhabitable, or one of the stars is actually going NOVA =

Then We're Royally Boned.

It'd be really fantastic to have ships with FTL drive or something to generate an Einstein - Rosen bridge, but it may not happen anytime soon, if at all. For the time being, if we want to leave the solar system to colonize other Earth - like / Potentially Earth - like planets, we need to have multi - generational ships that are the size of cities. Why not use colonized asteroids ( in future ) or cometary nuclei equipped with mass - driver engines for ships ?

Unfortunately the " Einstein - Rosen bridge " is theoretical until now , then we would not know the effects on human body when crossing.

However the article seems to show the scientific community to weak up looking at nearby stars of the Centauri : this is good.

In the old days it was sustained that habitable planets could NOT exist orbiting a Binary....that misconception revealed to be wrong.

The 3rd star in the century footh : Proxima might be part of a ternary system.....or may be NOT part of the Alfa A & B.

For the time being it is better to do what we can do and can afford: studying the stars and related habitable planets.

Futuristic space ships large like a town and with thousand of people on board are still part of Fiction moovies.

Who could afford the costs , assumed it will be feasible ???



Yes, it's too bad that we haven't been able to find one of those ruddy Stargates !!!!

YES - Multi - generational space - craft would take decades to build & crew / populate, but are still within the realm of possibility, although the Mass Driver / rail - gun tech to propel them is supposedly still on the drawing board.

ANYWHO, unless we discover a massive breakthrough in physics, there is NO WAY we are getting to the Centauri system within a single lifetime or less, I think we can all agree on that.

Radial Velocity has its drawbacks. If the plane of the planet's orbit is perpendicular to us, the observers, we won't really see anything with this method :( Do we know anything about the orientation of the axis of rotation of the stars in Alpha Centauri w.r.t us?

Dredd why are u worrying about whats going to happen to our sun or other suns a million years from now? I dont think we have to worry whats going to happen to our sun in the next 10,000 years.About taking 75,000 years to get there at the current speed of Voyager its wrong.If theres ever going to be a trip to the nearest star it wont be the way voyager is traveling with no propulsion system only using gravity to travel.Theres already propulsion systems that can travel at 10% the speed of light(on paper).At 10% it will only take 40 years to get to the nearest star.Its very possible that in the next 100 years there will be systems that can travel at 20 to 30 percent.

We may be wise to try to have space travel to another home world fine tuned in a million years.

You are joking right?
In my opinion it will take less than 200 to 300 years.

Take a 500 PW laser and a several kilometre wide focusing lens.

Take a 99.9% reflective sail, 14 kilometres across.

Stick as much cargo to the sail as you want, as long as you don't exceed fifty thousand tonnes.

Enjoy, as you are accelerated to the stars at seven gees.

Though travel to Alpha Centauri at speed of light might not be possible, we could conceivably develop a mode of transport that traveled at half speed of light. That could get us there in eight or so years. I explore this possibility in my novel Borrowed Tides.

Thanks for citing the alpha Centauri program at Mt John in New Zealand. We began our work on this system in 2007 and our team (Mike Endl, Texas; Stuart Barnes, AAO; Rob Wittenmyer, Univ NSW and me, Univ Canterbury, NZ) is pushing ahead as fast as possible. Our aim is 10000 high S/N spectra of each of alpha Cen A and B per year, using Hercules, the world's first fibre fed vacuum echelle spectrograph. Simulations based on our data show that an Earth mass planet at 1 AU is detectable after about 20000 spectra in about 2 years.

anti matter rocket. solar sails.Nuclear Pulse Propulsion. Stasus technology. If everyone on planet earth worked out their problems and started working together We could make it to another solar system in less than a thousand years. but I would give it more like a couple thousand years that it would actually be carried out.

@ Dredd "If we haven't found a way off this rock in a million years, I'll be really disappointed"

Why? You wont even be here to be disappointed!!

The Wright brothers first flew their powered kite in 1903. Less than 66 years later, man first walked on the moon. That's pretty amazing. If it wasn't for budget constraints, we could probably be at Alpha Centauri within 200 years.

Better look for Pandora at Sirius A instead of Alpha Centauri? There are evidence of giant Jovian Planet around Sirius A highly likely? And there are rumors about third object with Sirius B around Sirius A?

Better look for Pandora at Sirius A instead of Alpha Centauri? There are evidence of giant Jovian Planet around Sirius A highly likely? And there are rumors about third object with Sirius B around Sirius A?

avatar would have been more credible had the movie been set in the year 3154 , the idea that we could have colonised a planet four and a half light years away within 150 years ago is ludicrious

"avatar would have been more credible had the movie been set in the year 3154 , the idea that we could have colonised a planet four and a half light years away within 150 years ago is ludicrious"

Avatar is scienc FICTION. And in science fiction you have faster than light travel, like, for example, the warp drive of Star Trek.

Okay to all you guys saying traveling there would be impossible. Please think for a minute. Humans have been doing the impossible for thousands of years now. The fact that we can communicate like this is one of the impossible things we now take for granted.

the other point is that by the time we can develop a space craft that could safely transport humans to another star we would not necessarily need to find a habitable planet. We would already be a space culture very comfortable as Living on our space ships.

this would be especially true for a multi-generational trip.

Heck I wager that by the time we make this possible people generatins of people will have been born and raised in space. setting a slow course for the nearest star wuld not change the lives of the people on board at all. They would live die have children and one day look out the window and say hey look we are there. Then carve a monument out of an asteroid to commemorate their ancestors that set them on this journey. if there is a good planet to terraform maybe they will. If not they will continue living in space stations. culturally they would be very very different than we are. Nothing really would change much for such space travelers other than the view out the window.

what am saying is if you live in a gigantic Winnebago traveling is just part of your day. It would not matter about the destination to most of the crew. Just the journey.

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.)