What do you mean you've never been to Alpha Centauri? Oh, for heavens sake mankind, it's only four light years away, you know.

October 16, 2012 3:58 PM

A planet with about the same mass as Earth has been discovered in orbit around Alpha Centauri B, a star in the Alpha Centauri triple star system - the solar system's closest neighbor, a mere 4.3 light years away. Alpha Centauri B is very similar to the Sun, and this marks the first planet with a mass similar to Earth ever found around a Sun-like star. However, the planet is orbiting at a distance of about six million kilometers, much closer than Mercury is to the Sun in the Solar System, so temperatures above 400 degrees Celsius may make vacationing there unpalatable even for the most dedicated beach-goer. However, lead paper author Xavier Dumusque called it "a major step towards the detection of a twin Earth in the immediate vicinity of the Sun."
posted by kyrademon (55 comments total)

This may explain why we haven't seen Superman for a while.
posted by arcticseal at 4:08 PM on October 16, 2012 [1 favorite]

I was curious how far away it was in terms that make sense to my daily experience, and I found out it would take a mere 79 billion years to get there, if I drove at the speed limit in Canada. Space is pretty big.
posted by Blazecock Pileon at 4:11 PM on October 16, 2012 [5 favorites]

The "B" ark folks probably won't read the fine print, so we're good.
posted by maxwelton at 4:12 PM on October 16, 2012 [5 favorites]

No longer mere earthbeings and planetbeings are we, but bright children of the stars! And together we shall dance in and out of ten billion years, celebrating the gift of consciousness until the stars themselves grow cold and weary, and our thoughts turn again to the beginning.
posted by Apocryphon at 4:13 PM on October 16, 2012 [16 favorites]

Pretty bloody cool.

Can someone who knows more about this than me enlighten me as to why all these planetary systems they're discovering seem so different than our own? I mean, an Earth-sized planet only 6 million kilometers from the star. That's weird isn't it? Or is it to be expected, and our solar system is weird? How is all this new data shaping our understanding of how planetary systems form, and what the norm is?

Or does it just come down to our detection ability being biased towards, say, giant planets, or planets very close to stars?
posted by Jimbob at 4:15 PM on October 16, 2012 [1 favorite]

I was curious how far away it was in terms that make sense to my daily experience, and I found out it would take a mere 79 billion years to get there, if I drove at the speed limit in Canada. Space is pretty big.

There's nothing around for, like, miles. I'm pretty sure you could get away with doing 120.
posted by saturday_morning at 4:17 PM on October 16, 2012 [22 favorites]

That's weird isn't it?

Why would that be considered weird?
posted by Brandon Blatcher at 4:17 PM on October 16, 2012

Why would that be considered weird?

That's what I want to know. I mean, presumably theories have been established regarding the physics behind the development of our own solar system. Small rocky planets close to the star. Big gassy planets further out.

But systems we're discovering seem to have, for example, giant gassy planets really close to the star, going around at a rapid pace.

I guess I'm trying to say; I presume all these discoveries are causing some big shifts in traditional models of planetary system formation.
posted by Jimbob at 4:21 PM on October 16, 2012

Dumusque presumably means in the immediate vicinity of a Sun, or else he thinks we're going to find counter-earth.
posted by leotrotsky at 4:23 PM on October 16, 2012

There's nothing around for, like, miles. I'm pretty sure you could get away with doing 120.

That would allow time for bathroom breaks, too. I like your thinking.
posted by Blazecock Pileon at 4:23 PM on October 16, 2012 [6 favorites]

Can someone who knows more about this than me enlighten me as to why all these planetary systems they're discovering seem so different than our own?

Because the detection methods used are currently lacking in sufficient accuracy to detect small planets at Earth-like distances. Big planets? Yes. Small planets in much tighter orbits? Yes.

Much bigger telescopes will be needed to find the Golden Tickets.
posted by CynicalKnight at 4:24 PM on October 16, 2012 [4 favorites]

Big planets? Yes. Small planets in much tighter orbits? Yes.

Thanks, I figured that might be the case.
posted by Jimbob at 4:25 PM on October 16, 2012

> "Can someone who knows more about this than me enlighten me as to why all these planetary systems they're discovering seem so different than our own?"

It's mainly because those are the kinds of systems we've had instruments capable of detecting so far.

Right now, almost every planet detected was found using either Radial Velocity or Transits, which are most sensitive to planets rather close in to their stars. We've only just begun to find them using other techniques such as Direct Detection, which is most sensitive to planets far away from their stars. So there are a lot of holes.

As our instruments and techniques get more and more sensitive, we'll fill in those holes, but right now we honestly have little more than a vague idea whether the Solar System is typical or anomalous.

There do seem to be a wide variety of planetary system architectures out there, though.
posted by kyrademon at 4:27 PM on October 16, 2012 [2 favorites]

Or does it just come down to our detection ability being biased towards, say, giant planets, or planets very close to stars?

I'm no cosmologist, but my lay understanding is that it's at least partly this. Big planets and close planets exert more gravitational pull on their star than do small planets or far-away ones. That makes the star wobble more, which is one way that we detect planets. They also will transit their star more often if they are close (shorter orbital periods) and more dramatically if they are large (larger angular size) and that's the other way that we find planets.

I do think we've found some more Earth-like planets though, ones that are about our size and probably rocky and about the right distance from their stars. Not many but I do seem to recall we've picked up a few. Nothing so close-by as this though, sadly.

As to how much this sort of thing has been shaking up models of planetary system formation, that I couldn't speak to. Someone qualified would have to shed some light there.

What gets me though is that this is 4.3 light years away! That's talking distance! We need to broadcast some signals at that thing and see if anybody replies nine years later.
posted by Scientist at 4:28 PM on October 16, 2012 [1 favorite]

/self-conscious Canadian realizes he used miles and km/h in the same post, wonders what it all means
posted by saturday_morning at 4:28 PM on October 16, 2012

"In the years since planet-fall... AIGH OH GOD IT BURNS!! OH GOD WHY?!?"
posted by Grimgrin at 4:28 PM on October 16, 2012 [5 favorites]

CynicalKnight: Much bigger telescopes will be needed to find the Golden Tickets.

Unfortunately, if 2001 was any guide, Space Wonka will only confuse and terrify you for several minutes before you die of old age. Also there is no chocolate.
posted by gilrain at 4:29 PM on October 16, 2012 [1 favorite]

However, lead paper author Xavier Dumusque called it "a major step towards the detection of a twin Earth in the immediate vicinity of the Sun.

An intriguing observation Mr Dumesque. Or should I refer to you by your real name, TARL CABOT?
posted by Sparx at 4:32 PM on October 16, 2012 [3 favorites]

We'd better plan to launch a solar shade then. Who's with me?
posted by bonehead at 4:33 PM on October 16, 2012 [2 favorites]

Can someone who knows more about this than me enlighten me as to why all these planetary systems they're discovering seem so different than our own? I mean, an Earth-sized planet only 6 million kilometers from the star. That's weird isn't it? Or is it to be expected, and our solar system is weird? How is all this new data shaping our understanding of how planetary systems form, and what the norm is?

We already know that the solar system is "weird" in the sense of being a single-star system. Binary systems are actually more common.
posted by deathpanels at 4:37 PM on October 16, 2012 [1 favorite]

If bonehead is leaving, can I have his carbon footprint?
posted by Brandon Blatcher at 4:37 PM on October 16, 2012

> "I presume all these discoveries are causing some big shifts in traditional models of planetary system formation."

Picking up this question -- yep, indeed they have.

For example, when close-in giant planets were first discovered in the 90's, it was very startling. No one expected them to be so close to their stars. Giant planets have to form a great distance from the star, or they evaporate. Their existence has been seen as evidence that planets migrate in (and out, and all over the place.)

Depending on the theoretical group, you'll hear all kinds of different possibilities, and as has been said before, we still don't have the exoplanet data to test all the models. The "Nice" model is particularly interesting because it has stuff still moving around long after the primordial disk is gone, possible even up to a billion years.

As this relates to the Solar System, about 600 million years after the Earth formed, there was a period called the Late Heavy Bombardment, when everything in the solar system got hit by bucketloads of asteroids. The Nice theory postulates that migration of giant planets (some possibly even got ejected) ended up shooting asteroids all over the place.
posted by kyrademon at 4:40 PM on October 16, 2012 [3 favorites]

If only the Robinsons had made it there.
posted by DarkForest at 4:48 PM on October 16, 2012 [2 favorites]

>However, the planet is orbiting at a distance of about six million kilometers, much closer than Mercury is to the Sun in the Solar System, so temperatures above 400 degrees Celsius may make vacationing there unpalatable even for the most dedicated beach-goer.

So if Hercules (Alpha Centauri B) were approaching perihelion, then you mean we wouldn't expect native life activity to increase dramatically?
posted by subversiveasset at 4:48 PM on October 16, 2012 [2 favorites]

I hope this other Earth is cool like Earth, and not terrible like "Another Earth."
posted by drjimmy11 at 4:48 PM on October 16, 2012

> "Binary systems are actually more common."

That's actually very dependent on stellar mass. A lot of A stars are binaries, but only about 10% of M stars. Sunlike stars tend to be split about 50/50 between binary and single systems.
posted by kyrademon at 4:50 PM on October 16, 2012 [1 favorite]

So, that's Alpha Earth and we're Beta Earth? That explains why there's so many problems in this world, still working out the bugs.
posted by Brandon Blatcher at 4:54 PM on October 16, 2012

It's not only star wobble they're detecting, but also how much a star dims as a potential planet passes in front.

I get a little excited about every new planet discovered. Not because I think it's inhabitable or we'll visit it, but just because it's there! When I was growing up we didn't even know if extrasolar planets existed. Now we've found hundreds! That's quite a jump in only 20 years.
posted by sbutler at 4:58 PM on October 16, 2012 [3 favorites]

DataPacRat, by the way, had a simultaneous post on this which included a different link, and in a comment he pointed to responses from Phil Plait and Universe Today.
posted by kyrademon at 5:04 PM on October 16, 2012 [3 favorites]

How does this affect the odds of finding an actual habitable planet around Alpha Centauri A or B? A close planet might be the remains of a planet further out that 'spiraled in', but there's still some chance of having one further out, right? Or around Alpha Centauri A?

I wonder what the conditions are like on the surface? It seems like it'd almost have to not have much of an atmosphere - the solar wind must be an absolute beast that close in. Tidal lock also seems likely, unless it's a double planet or has a very large moon. I wonder if the sunlit side is partially or completely molten? I wonder how cold the cold side is, and if it collects frozen gases from the solar wind, from comets, etc.
posted by Mitrovarr at 5:08 PM on October 16, 2012

The Nice theory postulates that migration of giant planets (some possibly even got ejected) ended up shooting asteroids all over the place.

The migration probably shot asteroids all over the place, but there couldn't have been any ejections from our solar system because the rest of the orbits would have gotten whacked in the dance of ejection. Ejected (and star-swallowed) planets are how you get the hot jupiters, and systems where that has happened get vacuumed of loose junk like the Earth.
posted by localroger at 5:10 PM on October 16, 2012

Alpha Centauri B is very similar to the Sun

Well, sort of. Alpha Centauri A is 110% the mass of the Sun and has 150% the luminosity. They're both spectral type G2.

Alpha Centauri B is about 90% the mass and about 50% the luminosity. It is spectral type K1.
posted by Chocolate Pickle at 5:12 PM on October 16, 2012

We better get hopping on that cookbook--"How To Serve..." well, whatever we need to eat before it eats US.
posted by dutcherino at 5:20 PM on October 16, 2012 [1 favorite]

However, the planet is trailing an immense electromagnetic goatee. Lead paper author Xavier Dumusque called it "a major step towards the detection of a twin Earth in the immediate vicinity of the Sun."
posted by Durn Bronzefist at 5:21 PM on October 16, 2012

Metafilter: Space Wonka will only confuse and terrify you for several minutes before you die of old age. Also there is no chocolate.
posted by Lipstick Thespian at 5:43 PM on October 16, 2012 [1 favorite]

Yeah, after that loud-mouth in Croatia violated the embargo. A bunch of us space bloggers were patiently waiting for the embargo to lift, biting our collective tongues, when mouthy jumped the gun. We all knew about this a while ago.

We got an email from the ESO about an hour ago that said:

"I just spoke to the Head of Press at Nature, Ruth Francis, and we have agreed to LIFT THE EMBARGO on the Alpha Cen story IMMEDIATELY due to an unfortunate leak. You may run your stories."

Nature and ESO lift exoplanet embargo early following coverage by Croatian news outlet
posted by Nyrath at 7:22 PM on October 16, 2012

Are there Republicans on this planet?
posted by MattMangels at 8:22 PM on October 16, 2012

kyrademon: For example, when close-in giant planets were first discovered in the 90's, it was very startling. No one expected them to be so close to their stars. Giant planets have to form a great distance from the star, or they evaporate. Their existence has been seen as evidence that planets migrate in (and out, and all over the place.)

To add to kyrademon, other interesting but harder-to-explain findings include retrograde planets (orbiting opposite the direction the star is spinning), circumbinary planets (orbiting two stars at once), inflated planets (enormous and having the overall density of styrofoam), free-floating planets (presumably ejected from their host stars), many planets on highly-eccentric orbits (what, you thought they were almost circular, like our solar system?) and planets---or fragments the size of them---orbiting the dead, pulsing remnants of exploded stars. There's also the dual to the migration question---if these planets start migrating in until they're very close to their host stars...why do they stop?

Every time a better instrument or technique comes along, someone decides to observe a target which turns out to host something totally unexpected and confound theory for a bit. Exoplanets are an evolving, interesting field.
posted by Upton O'Good at 8:46 PM on October 16, 2012 [8 favorites]

Phil Plait: ALPHA CENTAURI HAS A PLANET!
posted by homunculus at 9:23 PM on October 16, 2012

Now Kim Stanley Robinson has to go back and change that chapter in 2312 about the nearest Earth-like planets being twenty light years (or 2,000 years of starship travel) away.
posted by A Bad Catholic at 9:25 PM on October 16, 2012

Much bigger telescopes will be needed to find the Golden Tickets.

actually, we may only have to wait a few more months...the Kepler probe has been detecting planets for almost 3 years now (using the transit method, where it looks for periodic dimming of a star due to eclipses...the time it takes to transit tells us its period, and the amount of dimming reveals its size). Most of the planets it's found have been, yes, big and/or close (though it has found some earth-sized ones) to their home stars, and only announced after three confirmed passes have been made. A 'golden ticket' planet is going to be earth-sized, orbiting a sun-like star, and orbiting at a similar distance and thus have a year near the length of ours. My guess: they've already found Earth 2...they just have to wait for pass #3 before they can publish...which could happen any day now.

(googling kepler just now revealed they just found a system of 5 planets orbiting within the distance of earth's orbit around KOI-500)
(oh, and Spitzer just found a DIAMOND PLANET!...so yeah...there's some weird ones out there...)
posted by sexyrobot at 10:01 PM on October 16, 2012 [2 favorites]

It seems like the process of planetary formation and distribution is highly dependent upon initial conditions. It isn't an assembly line where all star systems come out looking the same. Change a few parameters at the start and you can have planets all over the place.
posted by Kevin Street at 10:05 PM on October 16, 2012 [1 favorite]

OMG, wait...Alpha Centauri Bb? It's name is Beebee! :D
posted by sexyrobot at 10:14 PM on October 16, 2012

What gets me though is that this is 4.3 light years away! That's talking distance! We need to broadcast some signals at that thing and see if anybody replies nine years later.

A Zeta-beam so to speak.
posted by MartinWisse at 10:55 PM on October 16, 2012 [1 favorite]

Solar systems are like snowflakes; no two are alike...
posted by Renoroc at 1:39 AM on October 17, 2012

Space is pretty big.

Is it at all unusual how far away we are from other star systems? Are there systems out there cosily close to other systems that would have a reasonable chance of travel between them, or are we about average and everything in space is impossibly difficult to bridge?
posted by fightorflight at 8:28 AM on October 17, 2012

The closer you get to the galactic center, the more densely packed the systems are. In some areas near the galactic center, the average distance between neighboring stars is only 1000 AU (about a light-week).

Any planets there would be constantly bombarded by massive amounts of high-frequency radiation, though.
posted by kyrademon at 8:40 AM on October 17, 2012 [1 favorite]

Using current technology it would take a mere 80,000 years to reach this planet!
posted by cell divide at 8:56 AM on October 17, 2012 [1 favorite]

Using current technology it would take a mere 80,000 years to reach this planet!
posted by cell divide at 11:56 AM on 10/17


I'll start packing the car, you slip some Benadryl in the kids Kapri suns. Someone walk the dog and make sure she poops. I'm not stopping so she can smell every bush on Pluto.
posted by Divine_Wino at 9:59 AM on October 17, 2012 [1 favorite]

Using current technology it would take a mere 80,000 years to reach this planet!

Something like the Dawn spacecraft using an ion engine and powered by a nuclear reactor -- all existing technology -- could make it in a few hundred years.
posted by localroger at 10:03 AM on October 17, 2012 [1 favorite]

Alpha Centauri and the New Astronomy
posted by homunculus at 10:15 AM on October 17, 2012 [1 favorite]

Wow, it took four years of observation to discover this planet. That's dedication to science.
posted by Kevin Street at 3:31 PM on October 17, 2012

That's dedication to science.

Automation. You also have to rule out other possible beat frequencies between the remote planet's orbit and the Earth's day which only allows you to observe at night.
posted by localroger at 4:32 PM on October 17, 2012

Sid Meier knew
posted by talos at 8:02 AM on October 18, 2012

The binary stars of Alpha Centauri, as seen from Saturn
posted by homunculus at 11:39 AM on October 20, 2012