Habitable planets (new study out)

[Martin]

they haven't FOUND any habitable extrasolar planets

 

the new NASA study just assesses the chances of eventually finding earthlike planets in systems with hot Jupiters

 

http://news.bbc.co.uk/2/hi/science/nature/5325476.stm

BBC: "Earth-like planets may be common"

 

blog comment by astronomer (who partcipated in the new study)

http://scienceblogs.com/catdynamics/2006/09/exotic_earths.php

 

SEED magazing article:

http://www.seedmagazine.com/news/2006/09/several_planetary_systems_may.php

 

The main article got published in SCIENCE magazine, current issue

8 September. that is pretty good. Science magazine has decent editorial standards.

 

Exotic Earths: Forming Habitable Worlds with Giant Planet Migration

Raymond et al.

Science 8 September 2006: 1413-1416

[Sisyphus]

That's really exciting. Life similar to us (in the sense of being able to exist in the same environment) might be fairly common after all. And interstellar colonization is not necessarily an absurd proposition. Fantastic news on both counts.

[Martin]

That's really exciting. Life similar to us (in the sense of being able to exist in the same environment) might be fairly common after all. And interstellar colonization is not necessarily an absurd proposition. Fantastic news on both counts.

 

 

Hi Sisyphus, glad you replied! My take is that there is funding at stake so one has to look carefully twice to see if it is solid science. that is, the astronomy community has a stake in getting funded to SEARCH FOR EARTHLIKE PLANETS

 

Whether or not in future centuries one expects to be able to colonize, it is a question for NOW whether and how many there are. Regardless of our space-dreams, there is this objective scientific question of how common are rocky planets with water in the habitable zones around stars.

 

if they were to fake it and make it look like there might be a lot, maybe they could get more money for telescopes. telescopes able to see earthsize planets would be unprecedentedly big and sophisticated and beautiful

 

so they would have a motive to distort, and one is right to be CAREFUL AND SUSPICIOUS

=========

 

but in this case, for several reasons, already before reading it, I am inclined to trust this study.

 

One thing is that I have a longterm experience of Steinn Sigurdsson from his blog.

He has impressed me as frank, direct, open, humorous, he dislikes phony stuff.

Incidentally he comes from Iceland and is a good young researcher at Penn State (which has one of the best astro departments in the US) but that is maybe irrelevant.

 

A windowdressing NASA study is not what Steinn would do IMO. The study was FUNDED by the astrobiology division of NASA but my first impression is that it has good solid outside academic credibility.

 

Also Science magazine is pretty selective.

 

Well, that is a long roundabout way to say Hurrah, but I say it anyway:

 

yes it is reasonable to look diligently for earthsize wet planets.

 

there are probably going to be some!

[Martin]

Here is a summary of the Science magazine article

 

http://www.sciencemag.org/cgi/content/short/313/5792/1413

 

they based it on a computer simulation of the formation of planetary systems of the hot jupiter type

 

a giant planet migrates inward

 

turns out it is very apt to leave wet planets in low-ellipticity habitable zone orbits behind it as it migrates in towards the star.

 

they find that a THIRD or so of the systems discovered so far could have watery earthsize planets

 

I am beginning to be convinced

[Sisyphus]

I wonder, is merely being the appropriate (and nearly constant) distance from the sun, being of roughly Earth-mass, and having sufficient water and organic elements enough? Seems like you would at least also need a thick and largely non-reactive atmosphere, maybe a decent magnetic field, and perhaps other things as well. Assuming these calculations are right, I wonder how many of these "Earth-like" worlds are actually Earth-like.

[Daymare17]

This is supremely interesting. I am particularly intrigued by Alpha Centauri since that system is (a) the closest, (b) the most like our sun and © has not one but two habitable zones. Do you know whether they are going to focus on Alpha Centauri, and how likely it is that they will detect any habitable planets there?

[Martin]

..Do you know whether they are going to focus on Alpha Centauri,..

 

I don't, Daymare. AFAIK we don't have an expert here who follows the extrasolar planet search scene closely.

You have to use google industriously and follow the leads and scope it out for yourself.

 

If you find out anything please let us know. make a thread about it, or post additional info on this thread.

 

thx,

Martin

 

(PS I would advise your not getting narrowed down to the Alpha Centauri system prematurely---it would be great to have one or more habitable-zone planets to study even if 30-40 LY away. so much could be learned----and a robot probe could seed life on them if it were deemed advisable: grain from pyramids can still sprout )

[[Tycho?]]

I wonder, is merely being the appropriate (and nearly constant) distance from the sun, being of roughly Earth-mass, and having sufficient water and organic elements enough? Seems like you would at least also need a thick and largely non-reactive atmosphere, maybe a decent magnetic field, and perhaps other things as well. Assuming these calculations are right, I wonder how many of these "Earth-like" worlds are actually Earth-like.

 

Can't really say. The conditions required for life to form are unknown, even for life here on earth. Liquid water is pretty much the prime one; if there is liquid water then you probably have the chance for life.

 

Most of the other key characteristics can be implied by the pressence of liquid water. If there is liquid water then it is warm enough, at least for part of its year. Mass isn't really a problem; heavier or lighter than earth, life will adapt to those conditions. A fairly thick atmosphere is implied; water needs atmospheric pressure to remain liquid on the surface. Magnetic field is hard to say; its prime use would be defecting charged particles coming towards the planet that could harm life there. But a decent atmosphere should also be able to block most of the radiation, depending of course on what the star(s) in that system are like radiation wise.

[JHAQ]

I would assume the Drake equation still holds but its achilles heel is the degree of subjectivity assigned to any factor . Maybe this will give a better estimate of at least one of them .