Potentially Habitable Planet Found

Posted 24 April 2007 by Steve Reuland

Are you getting bored with Earth? Maybe you should consider a move to 581 c:

For the first time astronomers have discovered a planet outside our solar system that is potentially habitable, with Earth-like temperatures, a find researchers described Tuesday as a big step in the search for "life in the universe." The planet is just the right size, might have water in liquid form, and in galactic terms is relatively nearby at 120 trillion miles away. But the star it closely orbits, known as a "red dwarf," is much smaller, dimmer and cooler than our sun.

But don't pack your bags just yet...

There's still a lot that is unknown about the new planet, which could be deemed inhospitable to life once more is known about it. And it's worth noting that scientists' requirements for habitability count Mars in that category: a size relatively similar to Earth's with temperatures that would permit liquid water.

Still, it's a neat find. No word yet if the planet is "designed for discovery", but presumably anyone living there would have discovered those things that are easy to discover, and will therefore conclude that the planet must be situated just right for discovery. At least if their species has creationists. Below the fold I'll add some more excerpts from the article. Or you can just read the whole thing.

What they revealed is a planet circling the red dwarf star, Gliese 581. Red dwarfs are low-energy, tiny stars that give off dim red light and last longer than stars like our sun. Until a few years ago, astronomers didn't consider these stars as possible hosts of planets that might sustain life. The discovery of the new planet, named 581 c, is sure to fuel studies of planets circling similar dim stars. About 80 percent of the stars near Earth are red dwarfs. The new planet is about five times heavier than Earth. Its discoverers aren't certain if it is rocky like Earth or if its a frozen ice ball with liquid water on the surface. If it is rocky like Earth, which is what the prevailing theory proposes, it has a diameter about 1 1/2 times bigger than our planet. If it is an iceball, as Mayor suggests, it would be even bigger. Based on theory, 581 c should have an atmosphere, but what's in that atmosphere is still a mystery and if it's too thick that could make the planet's surface temperature too hot, Mayor said. However, the research team believes the average temperature to be somewhere between 32 and 104 degrees and that set off celebrations among astronomers. Until now, all 220 planets astronomers have found outside our solar system have had the "Goldilocks problem." They've been too hot, too cold or just plain too big and gaseous, like uninhabitable Jupiter. [...] The new planet seems just right --- or at least that's what scientists think. Eventually astronomers will rack up discoveries of dozens, maybe even hundreds of planets considered habitable, the astronomers said. But this one --- simply called "c" by its discoverers when they talk among themselves --- will go down in cosmic history as No. 1. Besides having the right temperature, the new planet is probably full of liquid water, hypothesizes Stephane Udry, the discovery team's lead author and another Geneva astronomer. But that is based on theory about how planets form, not on any evidence, he said.

73 Comments

CJO · 24 April 2007

120 Trillion miles... help me out: what's that in light years? Is it in our arm? I suppose the star's not visible with the naked eye, being a red dwarf, but is it near a brighter star? I'm excited.

The Sanity Inspector · 24 April 2007

Since this is a red dwarf sun, is the planet tidally "locked"? That is, is there any way of knowing if it is rotating?

Michael E · 24 April 2007

1 ly = 5.879 x 10E12 mi. = 5,879,000,000,000 miles.

581 c at 120 trillion miles is 120 x 10E12 miles away

So, 120 / 5.879 = 20.41 ly.

Not far at all. In fact, c circles one of the 100 closest stars to our solar system.

It's in the constellation of Libra.

CJO · 24 April 2007

Not far at all.

I like the way you think. Thanks for the info.

Nick (Matzke) · 24 April 2007

No word yet if the planet is "designed for discovery", but presumably anyone living there would have discovered those things that are easy to discover, and will therefore conclude that the planet must be situated just right for discovery. At least if their species has creationists.

Steve once again wins the Hilarious Anti-creationist Sarcasm Award for the month...

Nick (Matzke) · 24 April 2007

A planet that massive might have the problem of being so smooth it has a global ocean, which probably would make it tough to produce the concentration mechanisms (evaporation in pools etc.) that might be required for the origin of life. But you never know...

Anyway, give it 10 or 20 years and we will have earth-sized extrasolar planets coming out our ears, it's pretty clear that virtually ever star in a one-star system, and even many stars in double- and triple-star systems, has got planets, it's just a matter of detection limits at this point (currently we can only detect plants that are (1) big and (2) close-in.

shiva · 24 April 2007

PP prediction: When we find planets designed for observation they will be habitable! Bingo!

Tex · 24 April 2007

It's in the constellation of Libra.

Hey! I'm a Libra. More evidence for design.

steve s · 24 April 2007

Sorry for the rudeness, but:

Goddam, that is cool.

Bob O'H · 24 April 2007

Anyway, give it 10 or 20 years and we will have earth-sized extrasolar planets coming out our ears, ...

You should go and see a doctor about that. Bob

Dave Carlson · 25 April 2007

You should go and see a doctor about that.

Before it's too late for the rest of us!

Nick (Matzke) · 25 April 2007

Isn't there a better name than "581c"? Romulus or something?

Millipj · 25 April 2007

Maybe this is the planet the Intelligent Designers came from.

keiths · 25 April 2007

Since this is a red dwarf sun, is the planet tidally "locked"? That is, is there any way of knowing if it is rotating?

I think it would be impossible to tell without knowing the planet's composition (so you could estimate tidal deformation and dissipation) and its initial rotational velocity.

Alejandro · 25 April 2007

Prediction:

If the planet turns out to be unhospitable for life, creationists will say this proves the special character of planet Earth, which is the only one with the right characteristics for life and must obviously have been designed so.

On the other hand, if the planet turns out to be hospitable for life, creationists will say that the basic constants of the universe are especially fine-tuned so that many planets can support life, and this was obviously designed so.

Manuel · 25 April 2007

Typical ethnopocentric use of the word "discovery." Don't forget, Jesus was already there.

http://tinyurl.com/2khfrr

Karen · 25 April 2007

Isn't there a better name than "581c"? Romulus or something?

How about "Underprivileged Planet" ? Could this planet be the location where the DI has been building its extensive network of top secret ID research labs?

Laser · 25 April 2007

Sure, all IDists have a religous agenda.
— Overton

There, I fixed the typo for you.

Darth Robo · 25 April 2007

Overton... wtf? (pardon my french)

Oh, and what is the 'evil atheist agenda' by the way?

"Isn't there a better name than "581c"? Romulus or something?"

If it does turn out to have water, I do kind of like "Eden", just for the fun of it. :)

MartinDH · 25 April 2007

With the earth at the centre of a search and the first "Goldilocks" planet discovered a mere 20ly away, what does this do to the Drake equations when the (so far) the
density of habital plants is 2 in 30,000 cu ly?

Amazing discovery...all we need now is a few more and the ability to do spectropsy on the planets. It'll come.

Steve Reuland · 25 April 2007

Isn't there a better name than "581c"? Romulus or something?
— Nick

I suggest the name "Pluto" after the Greek god of the underworld. Since there are no planets named Pluto, this would be a good fit.

chunkdz · 25 April 2007

A planet that massive might have the problem of being so smooth it has a global ocean, which probably would make it tough to produce the concentration mechanisms (evaporation in pools etc.) that might be required for the origin of life.

LOL!

But you never know...

Yup!

Tyrannosaurus · 25 April 2007

Moronic statement of the week by Overton follows.
Potentially habitable planet found....lots of beating around the bush...

Therefore, there is no God.

The discovery of a planet with just about the right conditions (initially) to suspect the sustainability of life has no bearing what so ever with believing in God or not.
These fundies are really a beauty. Their stupidity is only surpassed by their mouths.

Now be a good fundie and crawl back into the hole you came from, OK?

Doug S · 25 April 2007

Since this is a red dwarf sun, is the planet tidally "locked"? That is, is there any way of knowing if it is rotating?

I don't think there's anyway to know for certain, at this point, but it's proximity to the parent star suggests that it would most likely be tidally locked (like our moon). How exactly that would effect the climate I'm not sure.

David Stanton · 25 April 2007

Overton,

I can make a tire wihout rubber. Therefore rubber does not exist.

Raging Bee · 25 April 2007

Doug S: if this planet is tidally locked, then the day side will be unbearably hot, and the night side unbearably cold. If the planet is covered with water, then all that water will be continually carrying heat from the day side to the night side -- not an ocean-current pattern I'd want to sail in. I couldn't say how much that water would do to equalize temperatures between the day and night extremes.

The weather on such a planet -- assuming it has an atmosphere, which, given an Earth-like size, it would probably have -- would be...interesting.

Peter Henderson · 25 April 2007

Still, it's a neat find. No word yet if the planet is "designed for discovery", but presumably anyone living there would have discovered those things that are easy to discover, and will therefore conclude that the planet must be situated just right for discovery. At least if their species has creationists.

So are Mars and Venus though. Both are within the "habitable zone" in our own solar system but both are so very different from the Earth. Still, I'm sure the YEC's will claim that this discovery confirms creation and a young Earth (like they did with "hot Jupiters"). It's bound to feature in AiG's "news to note" this coming weekend !

Doug S · 25 April 2007

if this planet is tidally locked, then the day side will be unbearably hot, and the night side unbearably cold. If the planet is covered with water, then all that water will be continually carrying heat from the day side to the night side --- not an ocean-current pattern I'd want to sail in. I couldn't say how much that water would do to equalize temperatures between the day and night extremes.
— Raging Bee

Yes, I agree, although our experience with tidally locked planets is limited ... there's the moon and Mercury, which have no atmosphere, and Venus*, which has a super-dense atmosphere and no ocean. I don't know of any planets with a liquid ocean which also are tidally locked, so any statement on the climate of such a planet would be just a hypothesis or conjecture at this point. I'm sure people will soon be firing up the computer models to try to get more detailed answers, but they'll still be quite rudimentary and not well tested (look at how well we can model our own climate given the extensive dataset that we have)**. I do agree with you that the weather patterns would be very interesting! As would be the life that could tolerate such conditions! Doug S * Mercury and Venus are not completely tidally locked, but they have extremely long days, and would be the best example of what a completely tidally locked planet would have. Also, for an observer on the moon, a "day" with respect to the sun would be a month long, or one lunar revolution, since the same face always points towards the Earth. ** I'm not suggesting that climate scientists are wrong, just that it has taken an incredible amount of work (and data) to get the consensus that they have now.

Steve Reuland · 25 April 2007

Doug S: if this planet is tidally locked, then the day side will be unbearably hot, and the night side unbearably cold.
— Raging Bee

Actually, according to the Bad Astronomy blog, that's not necessarily the case:

If so, how does this [tidal locking] affect the atmosphere? Models indicate that the air should carry the warmth of the star around the planet, so the temperatures should actually be fairly moderate on both the day and night sides of such a world. But if it's covered by an ocean, how does having one side of the planet eternally locked into daylight affect it? Criminy, what would life be like on a tidally-locked ocean world?

So the atmosphere would apparently be more or less moderate across the planet, but the ocean (if there is one) would probably transfer heat more slowly, and thus you'd see some significant differences in temperature. It'd make for some interesting weather, that's for sure.

Raging Bee · 25 April 2007

Steve: how effective would the atmosphere be in moderating the GROUND temperature? I'm no expert, of course, but it seems to me that the ground on the day side of a tidally-locked planet would pick up and store too much heat for an atmosphere to distribute to the night side. That is, after all, a LOT of rock to cool on one side, and a lot of rock to heat on the other.

This would probably not be a problem if the entire surface was covered by a global ocean, which would act as both a heat-exchanger and a shield.

jeannot · 25 April 2007

A planet that massive might have the problem of being so smooth it has a global ocean,
— Nick

Why? As far as I can tell, it's not the relatively small size of the Earth that allows mountains to rise. It's not like asteroids. As long as plate tectonics occurs, orogenesis should happen.

raven · 25 April 2007

My planetary design school {who said ID was useless :>)} told me about these kinds of worlds.

Being close to a red dwarf and in the habitable zone, it is likely to be tidally locked or at least have long days like mercury and venus.

Heat distribution might not be a problem. The theory is that the atmosphere will distribute heat reasonably well from day to night side. But it will be very windy all the time. Thermal differentials drive wind and there will be a big difference in insolation. By windy I mean permanent jet stream class wind.

This planet is 5 times earth. Gravity should be higher, atmosphere much denser, relief much lower. The wind would be a significant erosional force over time. If there is a lot of water, it might well be a water world. Even with a water world, there should be some land due to planetary cooling, plate tectonics, volcanoes.

Habitable for what? Microbes and other life adapted to whatever the conditions are would find it perfectly normal. We might not be impressed. There is a strong argument for taking care of our own life support system.

fnxtr · 25 April 2007

My planetary design school {who said ID was useless :>)} told me about these kinds of worlds.

Was Slartibartfast in your year?

raven · 25 April 2007

Was Slartibartfast in your year?

No, it has already graduated. I'm still taking planetonics and accelerated subduction. We won't even get into genomics and lifeology until next year. They do have a great course on how to antique your planet so it looks a million times older than it is.

Henry J · 25 April 2007

I suggest the name "Pluto" after the Greek god of the underworld.

I dunno - Pluto might be a Goofy name for a planet.

David B. Benson · 25 April 2007

Hmmm, the TNYT article on 'c' said something about five times as massive as good ol' Terra. No large land animals?

Michael E · 25 April 2007

"Was Slartibartfast in your year?"

"No, it has already graduated. I'm still taking planetonics and accelerated subduction. We won't even get into genomics and lifeology until next year. They do have a great course on how to antique your planet so it looks a million times older than it is."

This made me think of Harry Potter's school, only better. There have been a lot of great stories about kids at true UNIVERSE-ities, but I'm ready for more!

Torbjörn Larsson · 25 April 2007

Its discoverers aren't certain if it is rocky like Earth or if its a frozen ice ball with liquid water on the surface.

According to the preprint it could marginally be an ice world at Venus albedo. But it is promising.

what does this do to the Drake equations

A cool thing is that the statistics shows that M stars have a higher probability for small planets, and modeling shows that these planets have a higher probability to lie within the habitable zone. As 80 % of nearby stars are M stars, and they haven't been much looked at for planets, the possibilities are interesting. Our closest star, Proxima Centauri, is an M star. The statistics for small planets (Neptune analogs or smaller, here) are still wobbly though. This added two Earth analogs to the small M star sample. On the SETI side, apparently Gliese 581 have been surveyed two times before. But they were old and probably fast general surveys, probably only radio SETI, so perhaps it doesn't say much. Hopefully someone is already doing a directed search by this time, perhaps adding optical SETI.

Torbjörn Larsson · 25 April 2007

how effective would the atmosphere be in moderating the GROUND temperature?

Depends on the atmosphere of course. Someone mentioned that Venus atmosphere efficiently distributes heat. With ~ 80 times Earth atmosphere pressure, I bet it does. :-)

A planet that massive might have the problem of being so smooth it has a global ocean

Apparently it is very dense, but the small radius results in about 2.2 g surface gravity. Mars has a surface gravity of 0.4 g and sports the highest volcano mountain at 26 km (no comparable other mountains because of lack of tectonic plates). Compared to our own hotspot volcanoes, say Mauna Kea of about 9 km total, it seems height scales well with surface acceleration. So I would expect that plate tectonics could make 1-2 km deep oceans with 4-5 km high mountains. Btw, apparently a requirement for moving plates is liquid water. Someone mentioned that "super Earths" may be much more hospitable for life than Earth, since the heated core life time would be much longer (and the M star lifetime as well). In spite of creationists, we seem to be born on a lousy planet. I haven't done the numbers, but perhaps this makes an increased available heat flow that could compensate somewhat for the increased acceleration.

Isn't there a better name than "581c"?

Considering the wait around Xena..., excuse me, Eris, it could be a while before an official name is set. Unfortunately, IIRC the latest planet naming convention was a compromise with definitions based locally. I'm not sure any extraterrestrial planet has a memorable name yet.

something about five times as massive as good ol' Terra. No large land animals?

You tell me. 2.2 g doesn't sound like much, but perhaps elephant sizes are out. Oh, and these are lowest numbers, since interferometry doesn't know about tilt. But apparently the highest numbers aren't too far away.

steve s · 25 April 2007

Yeah but IIRC, the radius is 50% larger, so weight on the surface would only be a little over twice that on earth. So, probably no brontosauri there, but you could get animals of some decent size.

steve s · 25 April 2007

Whoops. That swedish guy beat me to the punch.

Torbjörn Larsson · 25 April 2007

Stumbled on some more sundry notes:

* ScienceBlogs rumor is 3 more releases of planets within a few weeks. May be small ones, considering the context to mention it.

* 1:1 tidal lock isn't the only possibility, as for related rotational locks. Mercurius have a 3:2 lock, for example, which helps distribute heat.

But unfortunately it seems the planetary formation models (IIRC) favors 1:1 lock.

* The same formation models favors a water world (deep ocean). Water is a green house gas, and people have mentioned 40 to 900 Celsius hot atmospheres by now. Seems the albedo temperature balance must be adjusted upwards, most likely.

- That swedish guy

Nick (Matzke) · 26 April 2007

* 1:1 tidal lock isn't the only possibility, as for related rotational locks. Mercurius have a 3:2 lock, for example, which helps distribute heat.

Mercury has a pretty eccentric orbit which matches up with the 3:2 lock. This new guy might also, if it's anything like many of the other extrasolar planets recently found. If it had a 3:2 lock on a 14-day orbit that's what, a 20-day "day"? [/wild speculation] [start slightly less wild speculation] Also, if it is a 1:1 lock, I imagine the dark side would freeze solid much like our poles in the local winter. Water would probably evaporate on the hot side and freeze out on the cold side, which doesn't sound very sustainable to me, but libration and glaciers and the rest would inevitably melt some of it and get it back over to the edge at least. Maybe there's a nice temperate 5-degree ring stretching along around the twilight zone of the planet, with the "seasons" and "days" set by librations etc. (If anyone uses the above idea in their next scientific paper or science fiction novel, I expect a citation!)

Nick (Matzke) · 26 April 2007

The view from an official planet modeler:

Big news today from the Geneva extrasolar planet search team. Using the HARPS instrument at La Silla, they have announced the detection of an Msin(i)=5 Earth Mass planet orbiting the nearby red dwarf Gliese 581. The planet has an orbital period of 12.9 days, which places it squarely within the habitable zone of the parent star. The planet probably migrated inward to its current location from beyond the "snowline" in GL 581's protostellar disk, and so its composition likely includes a deep ocean, probably containing more than an Earth's mass worth of water. Atmospheric water vapor is an excellent greenhouse gas, so the conditions at the planet's atmosphere-ocean boundary are probably pretty steamy. It's also possible, however, that the planet formed more or less in-situ. If this is the case, it would be made from iron and silicates and would be fairly dry. It's unlikely, but not outside the realm of possibility, that this could be a genuinely habitable world. There's no other exoplanet for which one can make this claim. In short, it's a landmark detection.

Nick (Matzke) · 26 April 2007

PS: They also link to the PDF of the paper:
http://exoplanet.eu/papers/udry_terre_HARPS-1.pdf

Nick (Matzke) · 26 April 2007

Oh, and apparently the guys at the systemic blog had this planet pegged in their database by 4 different people before it was published yesterday. That blog is going on my blogroll...

John Krehbiel · 26 April 2007

OK, how about some really fun speculation?

Oceans with huge tidal bulges, sunward and anti-sunward. Permanent low pressure system on sunward side results in nearly hemisphere-wide hurricane. Low sea levels between sunward and anti-sunward mean any land is there, right at the permanent termiator.

Constant twilight on the landmasses, constant hurricane to sunward, possibly an ice cap to antisunward.

Of course I have no idea if any of that actually works out, but pretty cool, huh?

Henry J · 26 April 2007

Re "You tell me. 2.2 g doesn't sound like much, but perhaps elephant sizes are out."

What about bandersnatchi? (If I spelled it right.)

Henry

chunkdz · 26 April 2007

The planet probably migrated inward to its current location from beyond the "snowline" in GL 581's protostellar disk, and so its composition likely includes a deep ocean, probably containing more than an Earth's mass worth of water.

ROFL!

ben · 26 April 2007

Why does that amuse you, chunky?

Raging Bee · 26 April 2007

GL 581's protostellar disk has a "snowline?" Does this mean there's good skiing and snowboarding to be found there?

GvlGeologist, FCD · 26 April 2007

Posted by Torbjörn Larsson on April 25, 2007 6:29 PM (e) Mars has a surface gravity of 0.4 g and sports the highest volcano mountain at 26 km (no comparable other mountains because of lack of tectonic plates). Compared to our own hotspot volcanoes, say Mauna Kea of about 9 km total, it seems height scales well with surface acceleration. So I would expect that plate tectonics could make 1-2 km deep oceans with 4-5 km high mountains. Btw, apparently a requirement for moving plates is liquid water.

Mauna Kea is one island in the Hawaii-Emporer Seamount chain. The Pacific Plate has been moving over a magma-producing stationary hotspot in the Earth's mantle for at least 80 million years. My understanding is that the size of Mons Olympus on Mars is more due to the lack of Plate Tectonics over a hotspot, so that the magma was concentrated in one location, not to the lesser gravity. So it is quite possible that we could see quite large mountains on the new planet if it doesn't have Plate Tectonics. On the other hand, the reason that Mars doesn't have Plate Tectonics while the Earth does is thought to be the larger amount of heat generated by radioactive decay in the earth (due to it's greater volume), so probably we would expect PT on the new planet. What's the logic behind water being a requirement for plate tectonics (which is primarily an internal process)? I've never heard that anywhere before.

Posted by John Krehbiel on April 26, 2007 6:58 AM (e) Oceans with huge tidal bulges, sunward and anti-sunward. Permanent low pressure system on sunward side results in nearly hemisphere-wide hurricane. Low sea levels between sunward and anti-sunward mean any land is there, right at the permanent termiator. Constant twilight on the landmasses, constant hurricane to sunward, possibly an ice cap to antisunward.

It would be interesting to run the numbers on the tidal bulge. Don't ask me - I know it's possible, but I don't know the math. I bet some physical oceanographers are doing it right now. The tidal bulge is dependent on at least 4 factors: size of ocean, size of planet, distance to tide creator, and size of tide creator. The earth's tide is due to both the moon and sun, with the effect of the moon (much closer but much less massive than the sun) being twice as important as the sun's effect. The moon's effect is greater because the difference between the pull of the moon on opposite sides of the earth is greater than the difference between the pull of the sun on opposite sides of the earth. Now, the star that our new planet circles is in between the sizes and distances of the sun and moon. The increased distance (relative to the moon) argues for a lesser tide, while the increased size of the star relative to the moon) argues for increased tide. The larger gravity of the planet argues for lesser tides, while the larger diameter argues for a greater tide. If the oceans are global and/or deep, that will lead to larger tides, while shallow and/or more restricted oceans will lead to smaller tides. NEED. MORE. DATA. (and also some calculations based on reasonable variation in sizes of oceans) Last comment: because the Coriolis effect will reverse on opposite sides of the equator, there could be two permanent cylclones on the sunward side of the planet, one in each hemisphere!

Nick (Matzke) · 26 April 2007

If the planet is tidally locked in 1 rotation per 1 orbit, then presumably the only tides would come from slight orbital variations, and from the other nearby planets. Which could actually be somewhat noticeable since the neighbor planet is 15.6 times more massive than Earth and may get within 12.5 Earth-Moon distances (using wikipedia numbers)...

Torbjörn Larsson · 26 April 2007

and apparently the guys at the systemic blog had this planet pegged in their database by 4 different people

Yes, but the systemic site notes that the likelihoods were pretty low. Still, a nice result for that project, and I expect they will improve their methods.

What about bandersnatchi?

As I understand it, bandersnatchi are irreligious so don't have mass.

a "snowline?" Does this mean there's good skiing and snowboarding to be found there?

I did a double-take too. I guess that is the boundary for volatiles, especially water, frozen out. Most comets are "dirty snowballs", you know. ;-) (At least in current thinking.) So while skiing is out, I think one could have some fun building snow sculptures and pitching (dirty and dangerous) snowballs.

So it is quite possible that we could see quite large mountains on the new planet if it doesn't have Plate Tectonics.

Good. I did a quick and dirty estimate, and so I wasn't concerned with the possibility for an even larger hotspot volcano for a slower plate.

the reason that Mars doesn't have Plate Tectonics while the Earth does

Um, I thought the water explanation has been proposed to explain why Venus doesn't have plates either. The latest imaging methods shows that a lot of water is drawn down by the plates and caught in the rocks. I picked the 'fact' up somewhere, and I have found by googling that it was a press release for a new paper with some exciting measurements and this hypothesis. Not exactly verified science:

Previous predictions calculated that a cold ocean slab sinking into the earth at 1,200 to 1,4000 kilometers beneath the surface would release water in the rock that would escape the rock and rise up to a region above it, but this was never previously observed. "That is exactly what we show here, the exact depth and high attenuation amounts right above it," Wysession said. "I call it the Beijing anomaly. Water inside the rock goes down with the sinking slab and it's quite cold, but it heats up the deeper it goes, and the rock eventually becomes unstable and loses its water. The water then rises up into the overlying region, which becomes saturated with water. "If you combine the volume of this anomaly with the fact that the rock can hold up to about 0.1 percent of water, that works out to be about an Arctic Ocean's worth of water."

Seventy percent of the earth is covered by water, which is very important for the earth's geology, serving as a lubricant that allows efficient convection and plate tectonics and the continental collisions that form mountains. "Water is like a lubricant, constantly oiling the machine of mantle convection which then drives plate tectonics and causes the continents to move about Earth's surface," Wysession said. "Look at our sister planet, Venus. It is very hot and dry inside Venus, and Venus has no plate tectonics. All the water probably boiled off, and without water, there are no plates. The system is locked up, like a rusty Tin Man with no oil."

( http://www.astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=2241 ) ... Finally, on tides: A large moon could dominate the tides. So we would need to know the likelihood for that.

GvlGeologist, FCD · 26 April 2007

Posted by Nick (Matzke) on April 26, 2007 1:15 PM (e) If the planet is tidally locked in 1 rotation per 1 orbit, then presumably the only tides would come from slight orbital variations, and from the other nearby planets. Which could actually be somewhat noticeable since the neighbor planet is 15.6 times more massive than Earth and may get within 12.5 Earth-Moon distances (using wikipedia numbers)...

There would still be a tidal bulge even if the planet did not rotate relative to it. It would just be stationary relative to the planet. But other tides from other planets....hmmm. Could be interesting. The planet is orbiting farther out from the star than our earthlike planet, according to what you just said. So, the tide would be more of a wobble back and forth as the other planet passes by (or more correctly, is passed by our earthlike planet) in their orbits, rather than a rotation around the planet. Ain't this a great universe? Of course, we don't know yet if there's any water there, so this is all hypothetical anyway.

Torbjörn Larsson · 26 April 2007

I should add on the water hypothesis that I haven't read the paper, but they discuss water and earth quakes. Perhaps they think that water helps release earth quakes to get the plates moving smoothly.

If anyone gets hold of the research I would be interested in an analysis. Or more images, the plots shown are nice.

John Krehbiel · 26 April 2007

Last comment: because the Coriolis effect will reverse on opposite sides of the equator, there could be two permanent cylclones on the sunward side of the planet, one in each hemisphere!
— GvlGeologist, fcd

Oops, right you are!

Henry J · 26 April 2007

Re "As I understand it, bandersnatchi are irreligious so don't have mass."

Oh. Learn something new every day, huh? :D

David B. Benson · 26 April 2007

Henry J --- The Lesser Bandersnatch only...

GvlGeologist, FCD · 26 April 2007

Seventy percent of the earth is covered by water, which is very important for the earth's geology, serving as a lubricant that allows efficient convection and plate tectonics and the continental collisions that form mountains. "Water is like a lubricant, constantly oiling the machine of mantle convection which then drives plate tectonics and causes the continents to move about Earth's surface," Wysession said. "Look at our sister planet, Venus. It is very hot and dry inside Venus, and Venus has no plate tectonics. All the water probably boiled off, and without water, there are no plates. The system is locked up, like a rusty Tin Man with no oil."

This is news to me. I checked out the article. Interesting. My understanding was that the standing hypothesis for the lack of PT on Venus is that the lithosphere of Venus is simply too warm to subduct. This agrees with the current leader for the cause of plate tectonics: the weight of the subducting (downgoing) plate. This is bsed on a correlation between plate speed and subduction zone length. On the other hand, it occurs to me that the correlation could equally be explained by a large plate adding more water to the mantle. I guess we'll have to wait to see what further research reveals to us.

Nick (Matzke) · 26 April 2007

There would still be a tidal bulge even if the planet did not rotate relative to it. It would just be stationary relative to the planet. But other tides from other planets....hmmm. Could be interesting. The planet is orbiting farther out from the star than our earthlike planet, according to what you just said. So, the tide would be more of a wobble back and forth as the other planet passes by (or more correctly, is passed by our earthlike planet) in their orbits, rather than a rotation around the planet.

The bigger planet is actually inside the orbit of the Earthlike one. Then there is a smaller planet much further out. One might think that 2 planets close in like that would have to have some kind of orbital resonance or something, I have not seen this suggested though.

Nick (Matzke) · 26 April 2007

Heck, if 581c has a moon it might still be rotating, rather than tidally locked to the star. OTOH the kinds of orbital migration and close encounter events that move planets close in are probably not kind to moons.

GvlGeologist, FCD · 26 April 2007

The bigger planet is actually inside the orbit of the Earthlike one. Then there is a smaller planet much further out.

Sorry. I read

the neighbor planet is 15.6 times more massive than Earth and may get within 12.5 Earth-Moon distances

to be "12.5 Earth-Sun distances". It would still primarily generate a wobble rather than a rotational tide, as long as the large planet and smaller planet are not orbiting each other.

Nick (Matzke) · 27 April 2007

Heh. The creationists don't like this one bit. Guillermo Gonzalez of the Discovery Institute says:

You are right about the host star being an M dwarf posing problems for habitability. The smallest planet's eccentricity is comparable to that of Mercury, so it is probably locked into a 3:2 spin-orbit resonance. So, the planet will experience large temperature variations over the course of its orbit. What's more, because its rotation is slower, it should have a weaker magnetic field and be subject to enhanced solar wind stripping of its atmosphere. Finally, the fact that it has a mass at least 5x Earth's means that it will have a high surface gravity and less surface relief than the Earth -- meaning no dry land.

Hmm...something seems a bit fishy to me here.

You are right about the host star being an M dwarf posing problems for habitability. The smallest planet's eccentricity is comparable to that of Mercury, so it is probably locked into a 3:2 spin-orbit resonance. So, the planet will experience large temperature variations over the course of its orbit.

Its oh-so-long...13-day orbit. I guess the "days" would then be about 20 days long. There's no way anything could survive a hot or cold period 20 days long! I mean, it's obviously impossible!

What's more, because its rotation is slower, it should have a weaker magnetic field and be subject to enhanced solar wind stripping of its atmosphere.

Let's see, a "day" 20 days long -- that's 0.05 of Earth's rotation rate. A mass 5 times that of Earth, hmm, as a wild guess let's say 5 times the magnetic field. So, the magnetic field would be 0.25 that of Earth's. Yeah, there's no way that could work. Just look at Venus with practically no rotation and no magnetic field, I mean, her atmosphere is gon--hmm.

Finally, the fact that it has a mass at least 5x Earth's means that it will have a high surface gravity and less surface relief than the Earth -- meaning no dry land.

Yeah, so the atmosphere is being stripped off so there's clearly no way liquid water could persist without boiling off in the low pressure--no, wait a minute, there's so much water there's no land!

Sir_Toejam · 27 April 2007

Yeah, so the atmosphere is being stripped off so there's clearly no way liquid water could persist without boiling off in the low pressure---no, wait a minute, there's so much water there's no land!

well THAT explains the whole noah's ark thing. it didn't happen on THIS planet. damn alien bible.

Popper's Ghost · 27 April 2007

As I understand it, bandersnatchi are irreligious so don't have mass.

That's only true on Sundays.

Popper's Ghost · 27 April 2007

120 Trillion miles... help me out: what's that in light years?

Um, if you need help with that, what wouldn't you need help with? 120,000,000,000,000 miles / (~186000 miles/sec) /(60*60*24*365 sec/year) = ~20 years (more precision is silly, given the imprecision of "120 trillion").

Isn't there a better name than "581c"? Romulus or something?

The astronomers are informally calling it simply "c".

Torbjörn Larsson · 27 April 2007

Random notes from the web: - Gliese 581 has half the metallicity of Earth, which fits that it (and many more M stars) can have these dense planets that are assumed. - The hefty volume to surface ratio of the large core means more heat flow, so more energy for life to play with. - The star is about the same age as ours. Time enough for life... - It seems confirmed that earlier SETI search were mere minutes in general searches, and that people wants to make a dedicated search now. Perhaps also a new first, from planet search to SETI search...

My understanding was that the standing hypothesis for the lack of PT on Venus is that the lithosphere of Venus is simply too warm to subduct. This agrees with the current leader for the cause of plate tectonics: the weight of the subducting (downgoing) plate. This is bsed on a correlation between plate speed and subduction zone length.

Which in turn is news to me. I guess I liked the water hypothesis for the cool images of the measurements, and for the likeness to the old and in a way lovely Gaia hypothesis. (The Gaia proponents could use some facts that was later found to be in error. IIRC that some oxidized minerals were more malleable at some pressures and heats, and thus suggesting life creating an oxygen atmosphere sustained the habitable environment.) If there is a correlation found for the subduction zone, I prefer that explanation for the time being. Also, a selfcontained process is more likely to explain our PT, all else equal.

Torbjörn Larsson · 27 April 2007

One might think that 2 planets close in like that would have to have some kind of orbital resonance

Seems correct, IIRC it was suggested and accepted on some of the astronomy blogs that could mean a lock similar to, but not quite, 1:1 was possible. The basic lock seems fairly certain, people references model work on similar systems. Even though the massive planet has ~ 10 times the angular momenta of Earth, it is ~ 30 times more affected by its sun (distance and mass), not counting the effect of water. And since the star is about the same age as ours, planets have had plenty of time to waste momenta and lock.

OTOH the kinds of orbital migration and close encounter events that move planets close in are probably not kind to moons.

You could check the model papers. IIRC some of them shows disturbed planetesimals that could be caught later.

That's only true on Sundays.

That would make their mass complex.

Popper's Ghost · 27 April 2007

That would make their mass complex.

Ahem. Please attend to the following lesson by Lewis Carroll:

'You are sad,' the Knight said in an anxious tone: 'let me sing you a song to comfort you.' 'Is it very long?' Alice asked, for she had heard a good deal of poetry that day. 'It's long,' said the Knight, 'but very, VERY beautiful. Everybody that hears me sing it--either it brings the TEARS into their eyes, or else--' 'Or else what?' said Alice, for the Knight had made a sudden pause. 'Or else it doesn't, you know. The name of the song is called "HADDOCKS' EYES."' 'Oh, that's the name of the song, is it?' Alice said, trying to feel interested. 'No, you don't understand,' the Knight said, looking a little vexed. 'That's what the name is CALLED. The name really IS "THE AGED AGED MAN."' 'Then I ought to have said "That's what the SONG is called"?' Alice corrected herself. 'No, you oughtn't: that's quite another thing! The SONG is called "WAYS AND MEANS": but that's only what it's CALLED, you know!' 'Well, what IS the song, then?' said Alice, who was by this time completely bewildered. 'I was coming to that,' the Knight said. 'The song really IS "A-SITTING ON A GATE": and the tune's my own invention.'

Henry J · 27 April 2007

Re "That would make their mass complex."

So part of it would be imaginary?

Henry

Torbjörn Larsson · 28 April 2007

So part of it would be imaginary?

Um, I haven't worked with QFT but perhaps the following could happen: Tachyons have imaginary mass. To bring out a complex mass, specifically changing between real and imaginary values, I guess a sew-saw mechanism would be appropriate. (Such as the one who gives neutrino masses and makes them oscillate between different types.) I don't think it works in that way. But bandersnatchi are mythical beings - presumably they can do what they want. Hmm. Do we have a 'scientifically truthiness' proof that virtual religious personalities are a bit unstable? I wonder what Salvador Cordova would say, it seems like these things are up his a...lley.

Torbjörn Larsson · 28 April 2007

I must amend my earlier comment. Of course I didn't mean that "virtual religious personalities are a bit unstable". I must interpret it as "virtual religious personalities are a bit shifty". How silly of me!

Also, I came up with a "Salvador Cordova (TM) physically truthiness" argument for why this must be. Bandersnatchi are usually easy personalities, jumping about with great abandon and haste (tachyonic state). But on Sundays suddenly time seems to drag along (not so tachyonic state).

I blame the church. ;-)