Lots of Earth-like planets in Milky Way

[Smersh]

I'm afraid I can't post very much at the moment, due some problems on the home front, but I HAD to start a thread on this when I saw it.<br /><br />http://news.bbc.co.uk/1/hi/sci/tech/7249884.stm <div class="Discussion_UserSignature"> <h1 style="margin:0pt;font-size:12px">----------------------------------------------------- </h1><p><font color="#800000"><em>Lady Nancy Astor: "Winston, if you were my husband, I'd poison your tea."<br />Churchill: "Nancy, if you were my wife, I'd drink it."</em></font></p><p><font color="#0000ff"><strong>Website / forums </strong></font></p> </div>

 

[Smersh]

Edited thread title, from "hundreds" to "lots." <br /><br />If half of all Sun-like stars have these rocky planets, I don't know how many that would be, but I'm sure it's, well, a lot ... <div class="Discussion_UserSignature"> <h1 style="margin:0pt;font-size:12px">----------------------------------------------------- </h1><p><font color="#800000"><em>Lady Nancy Astor: "Winston, if you were my husband, I'd poison your tea."<br />Churchill: "Nancy, if you were my wife, I'd drink it."</em></font></p><p><font color="#0000ff"><strong>Website / forums </strong></font></p> </div>

 

[Smersh]

Oh I dunno. If 85% of stars in the Milky Way are red dwarfs (which I read somewhere,) maybe the thread title should read "hundreds" after all. <br /><br />I'm sure somebody can put me right here. I can always change the thread title back to "hundreds" if you like. Or a moderator can, as I can't be here much right now. I really don't mind!<br /><br />Maybe I should have posted this in the Monty Python thread ... <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <h1 style="margin:0pt;font-size:12px">----------------------------------------------------- </h1><p><font color="#800000"><em>Lady Nancy Astor: "Winston, if you were my husband, I'd poison your tea."<br />Churchill: "Nancy, if you were my wife, I'd drink it."</em></font></p><p><font color="#0000ff"><strong>Website / forums </strong></font></p> </div>

 

[lukman]

Earth-like what sense? the size? distance to a star? rotation period? ocean? if only size, there could be plenty, but earth ressemble life supporitng planet, very tiny chance. <div class="Discussion_UserSignature"> </div>

 

[robnissen]

Earth-like generally refers to a rocky planet not much more massive than earth, maybe 2X or so and orbiting its star at a distance where it could maintain liquid water. I agree that the vast majority of rocky planets around earth-size will not be in the habitable zone. But if just 1% of the 400 billion stars of the MW have earth-sized rocky planets, and 1% of those have earth-sized rocky planets in the habitable zone, that would still be 40 MILLION earth-like planets.

 

[Smersh]

40 million!? Well, that is, er , lots!<br /><br />The reason I originally put "hundreds," is because the article originally was headed "Hundreds of Earth-like planets in Milky Way," but on checking the article now on the same link, it's been amended to "Planet-hunters set for big bounty." <div class="Discussion_UserSignature"> <h1 style="margin:0pt;font-size:12px">----------------------------------------------------- </h1><p><font color="#800000"><em>Lady Nancy Astor: "Winston, if you were my husband, I'd poison your tea."<br />Churchill: "Nancy, if you were my wife, I'd drink it."</em></font></p><p><font color="#0000ff"><strong>Website / forums </strong></font></p> </div>

 

[Smersh]

Looks like this has been covered already in the thread started by Brellis, which I didn't notice at the time.<br /><br />Sorry about that. <div class="Discussion_UserSignature"> <h1 style="margin:0pt;font-size:12px">----------------------------------------------------- </h1><p><font color="#800000"><em>Lady Nancy Astor: "Winston, if you were my husband, I'd poison your tea."<br />Churchill: "Nancy, if you were my wife, I'd drink it."</em></font></p><p><font color="#0000ff"><strong>Website / forums </strong></font></p> </div>

 

[lukman]

The first 1% is ok to me, there are 4billion rocky planet like earth, but the second 1% is too optimistic, i think 1/1million is a realistic one (the one that can support life). So it will be 40 planets like earth in milky way. Lets move up a little. There are 500billion galaxies, so there are 20trillion planet like earth, 1/1million have a civilization and technology like us, that leaves us 20million. <br /><br />1 of 1million of them have a warp technology, so there are 20 civilization like startrek. <img src="/images/icons/smile.gif" /><br /><br />using optimistic figure you proposed, then we will have billions or trillions planet with startrek technology, <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[venator_3000]

Hmmm…I dunno. The 20 – 60 percent quoted seems like a pretty wide error bar. But that is likely due to the sampling method and the fact that the Spitzer Space Telescope is detecting emissions. Basically the IR signatures of warm clouds of dust around a given set of target stars.<br /><br />Whenever I see these estimates I consider the Green Bank or as it is more famously known the Drake Equation. <br /><br />In this case<br />N = R (Fp) (Ne) (Fl) (Fi) (Fc) (L)<br />Where<br />N = number of intelligent civilizations that we might be able to “talk” to<br /><br />R = average rate of star formation in the Milky Way <br /><br />Fp = percent of those stars that develop planets<br /><br />Ne = average of planets that can support life per star that has planets<br /> <br />Fl = percentage of worlds that develop some form of life <br /><br />Fi =percentage of worlds that that develop sophonts<br /><br />Fc = percentage of worlds with an intelligent species that develops the technology with which to communicate with other species in the Milky Way<br /><br />L = lifetime of such a race, specifically its technologically viable lifetime and how long it can successfully beam signals skyward.<br /><br />R at present is estimated as 6 stars/year form in the Milky Way<br /><br />Fp from the BBC article is 20 – 60 % or 0.2 – 0.6<br /><br />Ne = 0.0047. I am basing this on the fact that scientists have detected some 210 planetary systems and that in Astronomy and Astrophysics recently there were two very compelling arguments that perhaps one of these stars (Glieese 581 IV) might have a world that could be habitable. Drake estimated 2.<br /><br />Fl = 1 per Drake<br /><br />Fi = 0.01 per Drake<br /><br />Fc = 0.01 per Drake<br /><br />L = 10,000 per Drake. Although a study based on human, technological civilizations suggested the number is closer to 500.<br /><br />Let’s look at the number of communicationg species based on the 20% value with the possible habitable count based on current known planetary systems:<br /><br />N <div class="Discussion_UserSignature"> </div>

 

[qso1]

RobNissen:<br />Earth-like generally refers to a rocky planet not much more massive than earth, maybe 2X or so and orbiting its star at a distance where it could maintain liquid water.<br /><br />Me:<br />Correct from what I've seen so far.<br /><br />At some point, a definition of what constitutes "Earthlike" will have to be agreed upon. The illustration in the article header alludes to this situation by showing a range of cloud covered worlds. In our system, Mars and Venus could be considered earthlike because they are rocky and Venus is nearly earth sized and earth mass. But Mars and Venus also are much less conducive to "life as we know it" based on whats known of them to date.<br /><br />I can easily imagine worlds like mars but with thicker atmospheres, water if in the goldilocks zone etc. An earthlike Venus would of course, be less cloud covered, different atmosphere etc. A huge and probably nearly infinite range of earthlike world possibilities which hopefully, astronomers will categorize eventually. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[richalex]

I just roll my eyes now when news reports trumpet the discovery of a solar system "just like ours." They have said that several times over the last few years, then it turns out that "just like ours" refers to multiple gas giants bigger than Jupiter orbiting closer to their star than Mercury does to our Sun.

 

[robnissen]

<font color="yellow"> "just like ours" refers to multiple gas giants bigger than Jupiter orbiting closer to their star than Mercury does to our Sun.</font><br /><br />Perhaps, but not the one described in this article:<br />http://researchnews.osu.edu/archive/analog.htm<br /><br /><font color="yellow">The newly-discovered planets appear to be gaseous planets like Jupiter and Saturn -- only about 80 percent as big -- and they orbit a star about half the size of the sun. The star is dim and cold compared to ours, issuing only five percent as much light.<br /><br />Still, the new solar system appears to be a smaller analog of our own. The larger planet is about as massive compared to its star as Jupiter is to ours. The smaller planet shares a similar mass ratio with Saturn.<br /><br />Also, the smaller planet is roughly twice as far from its star as the larger one, just as Saturn is roughly twice as far away from the sun as Jupiter. Although the star is much dimmer than our sun, temperatures at both planets are likely to be similar to that of Jupiter and Saturn, because they are closer to their star.</font><br /><br />Same relative size as Jupiter and Saturn to their parent star (smaller than Jupiter and Saturn in our solar system), same relative orbit between the two planets as between Jupiter and Saturn, same temperature as Jupiter and Saturn. I would not "roll my eyes" at the statement that this system is at least similar to ours.<br /><br />

 

[richalex]

<blockquote><font class="small">In reply to:</font><hr /><p>I would not "roll my eyes" at the statement that this system is at least similar to ours.<p><hr /></p></p></blockquote>It is not similar to our; it is analogous to ours. It is no more like our solar system than the scale models in various countries.

 

[qso1]

I roll my eyes too but then again, I have to keep in mind the reporter has to jazz the report up to attract more readers. <br /><br />I'm waiting for the first images of earthlike worlds which will probably be no more than a couple of pixels but any data that can be gleaned from that will certainly be a quantum leap in our current understanding. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[mindopener9]

<p>Since the speed of light is the absolute cosmic speed limit, none of these supposed planets, even if any harbor intelligent tool-using species, could be presently visiting us. That is, if we assume no one can possibly be more advanced, technologically, than we already are. Unless, of course, they are very close, or very long-lived, or are using multi-generational, colony-type spacecraft. Or automated probes. </p><p>When I put it in these terms, it sounds stupid. Where the heck are all the visiting aliens????&nbsp;</p> <div class="Discussion_UserSignature"> We must progress and expand, or we will stagnate and die. </div>

 

[alokmohan]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Since the speed of light is the absolute cosmic speed limit, none of these supposed planets, even if any harbor intelligent tool-using species, could be presently visiting us. That is, if we assume no one can possibly be more advanced, technologically, than we already are. Unless, of course, they are very close, or very long-lived, or are using multi-generational, colony-type spacecraft. Or automated probes. When I put it in these terms, it sounds stupid. Where the heck are all the visiting aliens????&nbsp; <br />Posted by mindopener9</DIV><br /><br />There&nbsp; are&nbsp; no&nbsp; such&nbsp; earth&nbsp; lke&nbsp; plants.So&nbsp; we&nbsp; are&nbsp; talking&nbsp; of&nbsp; aliens?

 

[alokmohan]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>There&nbsp; are&nbsp; no&nbsp; such&nbsp; earth&nbsp; lke&nbsp; plants.So&nbsp; we&nbsp; are&nbsp; talking&nbsp; of&nbsp; aliens? <br />Posted byhttp://www.universetoday.com/2008/03/04/a-one-way-one-person-mission-to-mars/ alokmohan</DIV><br />