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Space Science

42 Worlds in 32 Days 150

Posted by timothy from the beats-old-phineas-soundly dept.
Odie writes: "Since the first discovery of a planet around another star in 1995, some 60+ planetary systems have been discovered. That's about one every two month, most of them uninhabitable Jupiter-sized heavyweights. Not much statistics to put in the Drake equation. Recently though, the OGLE team has come up with more than 42 new candidates. Nice in itself, but what is spectacular is that they spent only 32 days finding them! At that rate COROT should soon find plenty of worlds to explore for you budding Starfleet sailors! "
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42 Worlds in 32 Days More

42 Worlds in 32 Days

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  • 42.... (Score:4, Funny)

    by Anonymous Coward on Saturday March 02, 2002 @07:37PM (#3099343)
    Come on, need I say more?
    • Uh, "what's six times seven"!

      Or better yet, "what's six times nine"!
    • You might also say that some estimates of the Hubble parameter are 42 in its usual unit, kilometer/sec/megaparsec.
    • Why does 42 keep coming up again and again?

      For you Cisco people; how many have chuckled when you realized that the number to clear the startup config (config reg) on most cisco routers is 0x42 ?

  • Gattaca (Score:1)

    by NWT ( 540003 )
    In the end they'll send ships to every known and nearly habitable planet, because there a re sooo many unexplored planets waiting to be settled ... sounds nice, but a little far away. but i think it's cool anyway.

    • Re:Gattaca (Score:4, Insightful)

      by kesuki ( 321456 ) on Saturday March 02, 2002 @09:17PM (#3099587) Journal
      The radius of the milky way is 100,000 light years with an average thickness of 10,000 light years. There is a 30,000 light year thick bulge at the center of the galaxy where many of the hundred billion stars in this galaxy reside. I'm basing this on this page. [encyclopedia.com] at this rate of planetary discovery it seems that a high rate of stars may have jovian size gas giants. Until we have more data though it's a difficult number to determine. However jovian planets are largely hydrogen and helium gas. Potentially they could form anywhere a star could, while earth type planetoids would require enough dense matter to form into solid planets.
      these planets also have to form within the stars habitable zone. Still with roughly 4 billion cubic light years of milky way galaxy on average there are 25 stars within one cubic light year of each other. Meanwhile we're at a density rate of about 0.1 stars per cubic light year, meaning that even with an optimistic calcualtion the nearest earth like planet would be 50 light years. The nearest earth like planet in a habitable zone 150 light years away the nearest life inhabited earth like word 450 light years away and the nearest civilization some 1,350 light years away. That means SETI is a worth while project, but that unless we defy physics by coming up with a FTL drive there isn't any way we're meeting any alien races.
      Note these are Highly optimistic numbers and assume that every star system with as many jovian planets as ours would have as many solid planetoids like our system.
      • (* There is a 30,000 light year thick bulge at the center of the galaxy where many of the hundred billion stars in this galaxy reside. *)

        That place may not be a very safe place for life or settlement. Closely packed stars means more likelyhood that a nova or supernova will cook your home in radiation, not to mention more chances of collisions or orbit-disturbing close passes.

        Imagine a few Beetlejuices hanging around within a few light-years ready to go off any second.

      • at this rate of planetary discovery it seems that a high rate of stars may have jovian size gas giants. Until we have more data though it's a difficult number to determine. However jovian planets are largely hydrogen and helium gas. Potentially they could form anywhere a star could, while earth type planetoids would require enough dense matter to form into solid planets.

        Even systems with gas giants hogging the habitable zone have potential for life. With gas giants much larger than Jupiter seeming to be the norm, I'd assume we can expect that the giants would have larger moons better fit to life. So it doesn't matter where those solid objects form; as long as they are caught by a gas giant in the right orbit and happen to have the right composition, life could still arise in that system.

        I'd imagine that any new civilization on one of these moons would take less time to inhabit the many moons of a gas giant than we are taking to explore our mere one. So many fascinating spacial wonders would be right up close to entice intelligent beings to explore them. How beautiful it would be to have a Jupiter taking up most of the sky!
        • How beautiful it would be to have a Jupiter taking up most of the sky!

          ...and cooking your ass with quite a deal of radiation...

      • They've said it all:

        (snip)
        Just remember that you're standing on a planet that's evolving
        And revolving at 900 miles an hour.
        It's orbiting at 19 miles a second, so it's reckoned,
        The sun that is the source of all our power.
        Now the sun, and you and me, and all the stars that we can see,
        Are moving at a million miles a day,
        In the outer spiral arm, at 40,000 miles an hour,
        Of a galaxy we call the Milky Way.

        Our galaxy itself contains a hundred billion stars;
        It's a hundred thousand light-years side to side;
        It bulges in the middle sixteen thousand light-years thick,
        But out by us it's just three thousand light-years wide.
        We're thirty thousand light-years from Galactic Central Point,
        We go 'round every two hundred million years;
        And our galaxy itself is one of millions of billions
        In this amazing and expanding universe.
  • Why? Because it's much easier to see Jupiter then it is Earth. Stands to reason.
  • And to think we have just begun to scratch the surface of these extra-solar planetary bodies in their discovery. So far to date, all we have been able to easily spot is gas giants, much like Jupiter. With clearer, more deeper peering telescopes, we will soon be able to see more spherical aberition for smaller, earth size objects.

    At the current rate of discovery, and current rate of advancing techniques to discover these objects, it truly is a good time to live in this age of discovery!

  • Good first step. (Score:4, Interesting)

    by Restil ( 31903 ) on Saturday March 02, 2002 @07:50PM (#3099385) Homepage
    We need to get all the stars that have large planets identified as such, and hopefully all of the large planets in such solar systems. Then as our equipment gets better we'll be able to focus on even smaller changes, which will allow us to pick up earth sized planets or smaller.

    Also of interest are planets in habitable zones, even large ones. Moons around larger planets could work as well as earth does in the right orbit. Of course, being in such close proximity to a massive planet could present other problems, as massive bodies are more likely to attract other significantly sized rocks, as well as a LOT of radiation if there is a significant magnetic field.

    -Restil
    • Yes, but the extra radiation put out by a gas giant may very well increase the chances of live evolving on a life-supporting moon, so ya never know...

    • Re:Good first step. (Score:3, Interesting)

      by Captn Pepe ( 139650 )
      We need to get all the stars that have large planets identified as such, and hopefully all of the large planets in such solar systems. Then as our equipment gets better we'll be able to focus on even smaller changes, which will allow us to pick up earth sized planets or smaller.

      I assume that, by "smaller changes", you are referring to the detection of extrasolar planets by spectroscopic searching for the periodic velocity signature of an orbiting body. Unfortunately, this method will probably never be sensitive enough to detect an earthlike planet at earthlike distances; the smallest planets detected so far are roughly Jupiter-mass.

      On the other hand, direct optical observation of earthlike planets is possible using large interferometers. Note that this is probably only possible with free-flying space-based telescopes, but it might just be doable using terrestrial interferometric telescopes with advanced adaptive optics. What's more, interferometers can not only detect such planets, but should be able to resolve spectra for them, telling us immediately whether or not they are likely to be habitable or hosting life of their own. For instance, since starlight breaks down ozone, an ozone signature in a planet's spectrum would be an almost certain indicator of biological or exotic chemical processes at work producing large quantities of oxygen. And so on.
    • Yes, but life forms can develope that can withstand massive doses of radiation. Example: cockroaches. And cockroaches are pretty intelligent for insects too. What says that technologically advanced cockroaches couldn't develope on a heavily radiated moon of a large planet?
      • What says that technologically advanced cockroaches couldn't develope on a heavily radiated moon of a large planet?

        Well. Time to increase funding to nuclear weapon reseach, then. Or at least doing some basic research into the feasibility of remotely deloying really big roach motels.

    • Darn it, I hit submit too soon.

      What I was going to say was, if on the other hand your "smaller changes" refer to smaller perturbations to the light curve of a star, caused by smaller bodies transiting -- then, yes, it might be practical to detect earthlike bodies simply using more sensitive equipment. Personally, I kind of doubt that anyone will be able to see small bodies far enough from the parent star to be in the habitable zone, but the intrumentalists have certainly surprised me before.

      However, this method suffers from the same problem as velocity perturbation analysis, which is that it only tells you that a body is there, without giving much interesting information about it. Still, it makes a pretty nifty survey technique.
    • Misleading title and intro - they aren't all "worlds"....
      The transiting objects may be Jupiters, brown dwarfs, or M dwarfs. Future determination of the amplitude of radial velocity changes will establish their masses, and will confirm or refute the reality of the so called "brown dwarf desert".
    • Say 1/2 of all suns have a planetary system. (a resonable guess). Around 2/3 of these will probably have some rocky planets orbiting in the Goldilocks Zone. Often, there will be multiple rocky planets. Lets figure l rocky planet per star system, on average.(In our system, that's from Venus to Mars.)
      Around 2/3 of these rocky planets will have a stable orbit that is not too elliptical.
      Around 1/2 of these will have a thick atmosphere.
      Around 1/5 of these will have an atmosphere suited to primordial life.
      Around 1/3 of these will have liquid water.
      Around 2/3-1/2 of these will have primordial life.

      So the chances of any given star system having primitive life is around .7%.
      Maybe the chance of finding complex multicellular life is around .1%.
      The chance of finding intelligent life is lower still.
      I once calculated, with Drake's equation, that there is an average of one technical civilization per cube of space 4000 light-years on a side. So are chances of finding life in other star systems is quite good, but our chances of finding intelligent life is pretty dim.
      If we heard a signal, by the time our reply got back the civilization would probably be gone.
      On the other hand, I think my .7% estimate of simple life is actually kind of conservative. In our solar system, 1 planet has developed life, while Mars most likely used to have life. So that's two planets in our system alone that have or used to have life.

  • Life Imitating Art (Score:1, Interesting)

    by pryan ( 169593 )
    I wonder how much like Star Trek our future will be. If there is a resemblance, I wonder how much of it will be because we have Star Trek in our cultural history, or because it was a reasonable vision of the future. Somebody invent transporters already!
    • A lot of NASA people (including my father, who worked on Apollo and Skylab) have talked about how they were inspired by science fiction, and tried to make what they did as much like [fill in favorite SF book, TV show, or movie here] as possible. The problem is, of course, that there's a lot of basic science (as opposed to engineering) that needs to happen before we can even think about a Star Trek future. Warp drive and transporters aren't just neat future tech; at this point, they're fantasy, not SF. The fundamental discoveries required to make such devices might happen tomorrow, or in a thousand years, or never.
      • (* A lot of NASA people .... have talked about how they were inspired by science fiction, and tried to make what they did as much like [fill in favorite SF book, TV show, or movie here] as possible. *)

        Let's see, if I combined my favorite childhood shows, it would be something like:

        "Danger danger! Will Robinson!"

        "Shut up you blabber-bot, or I will reformat your rusted toaster-shaped head!"

    • I don't know about warp drive, but transporters may be closer than we expect. Checkout
      [nature.com]
      http://www.nature.com/nsu/010927/010927-11.html
      It is a little dated but interesting none the less.
    • Too bad that Star Trek had the following explanations for any technical questions.

      "How does the warp drive work?"
      "Very well, thank you."

      "How does the transporter work?"
      "It recalibrates the photonic field generators in the alternative energy matrix to recapitulate the baryonic flux."
  • It's amazing that they can find planets that quickly, even if they're giants and not terrestrial. The existence of so many jovian worlds out there lends itself to the idea that Earth-sized planets may not be all that uncommon either.

    I'm not sure if the "wobble" method of detecting extra-solar planets will ever be sensitive enough to detect planets like our own. I do have confidence however in the developing method of analyzing the light spectrum of a star to detect planets, and am really looking forward to seeing next-generation space interferometry telescopes. In fifty years could we have a visible-light image of another Earth out there?

    • It's amazing that they can find planets that quickly,
      It's like everything in science...the first one is the hardest. Once you are happy with your mechanism for determining that a blip is a planet; it is just a matter of brute force to replicate the experiment a few million times.

      This probably brings up the big ugly question of intellectual property. Does the person who found a new planet get to claim it, or are all of the planets found by a particular technique the property of the person who designed the technique? I am sure lawyers will spend millions of tax dollars deciding such important questions.
      • And who gets to name the multi-tentacled 4 eyed gray puddings that live on them??? Just wait until filthy rich folks are allowed to launch ships and homestead planets (why it's the planet of BillGatus!) Will the future founders of these planets get to pick their own forms of government? Will they quickly evolve so differently (both physically and culterally) that they won't even be recognizeable?

  • Lazarus Long (Score:1, Funny)

    by Alien54 ( 180860 )
    Lazarus Long had a quote someplace about the need to leave a planet when personal identification was required for those all around.

    Sounds like these are being discovered just about in time.

    ;-)

    Unless, of course, some of them are occupied. But what are the odds?

    • Hey! A Chtorr reference! Which of these 42 worlds do ya think is the Chtorr homeworld? When's the next novel coming out? The last one I read was about the airship expedition over the Amazon, ending with Jim and Liz getting medi-vaced out of the rain forest...to be continued....
      • Actually, I've been waiting for the next book for quite a while now.

        I just assumed the author had died before finishing the series.
  • It says "46 stars with transiting low-luminosity objects were detected" (i.e. planets). 42 of them had multiple planets. The total number of planets was 185. While the Slashdot summary is technically right, (185 is more than 42), saying that there are 185 more candidates is more accurate.
    • Actually actually... you've got it wrong. The total number of TRANSITS was 185. There are no multiple planets here, but 42 multiple transits. There were a handful of single tranists which are more iffy (can't compute an orbital period). By the way, the total number of planets is ZERO, so far in this experiment. Each of these transits could be caused by a non-planet (ie as star or brown dwarf.) Until information on the mass of the transiting object comes in, we don't have any planets yet.
  • Sometimes I really wish we'd spend more money and effort into discovery the deeper ocean. So far there's been less than 5% of the ocean being explored.

    When we run out of hospitable land on earth, the best option wouldn't be moon, mars, or any of these exotic planets. It would probably be the vast ocean on earth itself, either afloat or submerge.

    Recent discovery on the ocean floor has revealed a host of other life system unsupported by sun light. It is truely amazing. Yet despite spending 13 billion on NASA budget every year, we only have 3 deep sea subs that can venture into the deep..

    • Color me cynic (Score:2, Insightful)

      by belg4mit ( 152620 )
      Yes, that's a great idea. And so if the deep
      is still virgin by the time that we've *really*
      screwed everything up, why shouldn't it join
      the rest of the planet? At least there's
      nothing to wipe out on the moon. Well, there'd be one thing if we ever got off our collective
      duffs and did something, ourselves.

      And here's a news flash, the few billion
      spent on NASA is *nothing*, it's barely
      worth mentioning. It compares not to the rest
      of the budget, you want to know why congressmen
      and everybody focuses on it? Because it's high
      profile (because it works). It's easy to say,
      NASA, bof what have they ever done for me?
      I didn't fly to the moon, they're useless.
      The returns on investments in space far
      outweigh what we've put into it.

      Just think about (and these are only the most obvious):

      Telecom, sneakers, jeeps, Tang, alloys and
      other materials, pretty pictures for your desktop,
      and on and on and on.

      Not to say that NASA couldn't some things better,
      but that's a horse of a different color. And
      I'm not saying we shouldn't explore the deep
      oceans either, but we should be extremely osking
      careful when we do. But to compare deep sea
      to space is blasphemy.
    • Yeah, but there's a good reason why we focus on the stars rather than the oceans: It is easier to contain 15psi than to resist 100psi.

      Now, if we can get that liquid-rebreathing system working (and to a point where it doesn't cause chemical pneumonia in adults), then it becomes more feasible (as the walls of the vessel need to only be thick enough to hold your breathing medium).
      Unless of course, you happen to be a major government who can afford $500,000,000 for a submarine that can carry more than ten people.

      And I also think it's psychological.. it's more reasonable to imagine yourself living on another world with an atmosphere, than deep in an ocean.

      Look, I agree, it'd be cool to live underwater.. So, we need to learn how to build with diamond.

  • Sheesh, uh, buddy - it's a metaphor. Or did you go through all that just to get in your pun?
  • Well, I think I'd get a kick out of being in Starfleet (except for their massive military focus). But... budding? Humans don't bud.

    Main Entry: budding
    Pronounciation: 'b&-di[ng]
    Date: 1581
    Definition: Being in an early stage of development

    So really, humans ARE budding all across the world.

  • drake equation = retarded. (Score:5, Insightful)

    by drik00 ( 526104 ) on Saturday March 02, 2002 @08:13PM (#3099453) Homepage
    Every time i hear about "inhabitable" planets, or "signs of extraterrestrial life," i laugh my ass off, and i laugh harder the more educated that the idiot that mentions these things.

    I'm in no way a scientist, hell, I'm a Comm. Studies major, i have had a lot of biology classes, so i'm not totally ignorant either. However, it just seems that if we're really looking for life on other planets/celestial bodies, we need to quit thinking so close-mindedly.

    Let's say, for argument's sake, that life evolved much the way some scientists say it did, the whole Darwinian macroEvolution of the many species. What does that teach us when trying to look for other signs of life out there? well, i can tell you it definitely DOES NOT mean that we need to look for other earth-like planets with water and it DOES NOT mean we should say "well, there is an abundance of molecules that could form into DNA" or the presence of carbon means anything.

    What we need to look at is the *effects* of otherworldly life, and i'm not talking about the "face of Mars"...i'm talking about other signs, real signs of unnatural form/structure in space. We need to quit anthropomorphizing possible alien life and we need to quit looking for life "as we know it."

    Even in a time when new terrestrial life forms are being found in places where these educated scientists said no life could ever exist (undersea thermal vents, etc), the science community tends to want to look like life like us (not human, DNA/carbon based life).

    As far as we know, we're the exception, and there are interstellar races 10^6 times larger than we are that exist in the fusion reactors inside stars. I'm citing an extreme example, but my point is this: If there was life so extreme, how would we ever notice them? How would we ever contact them? With radio signals embedded with decodable messages? You could broadcast a voice talking over FM radio into space, and when it reaches an alien race, they never notice it because either they've moved so far past that technology or never had the need to use radio-type waves for communication purposes.

    IMHO, the only point in looking for "inhabitable" planets is for future colonization. All else is simply pointless.

    damn, that was my last $0.02...

    • Re:drake equation = retarded. (Score:5, Insightful)

      by s20451 ( 410424 ) on Saturday March 02, 2002 @08:34PM (#3099497) Journal

      Although I agree that the Drake equation is flaky science, I can't agree with most of what else you've said. For example:

      Even in a time when new terrestrial life forms are being found in places where these educated scientists said no life could ever exist (undersea thermal vents, etc), the science community tends to want to look like life like us (not human, DNA/carbon based life).

      Yes, the scientists found organisms that exist in places where they were previously unexpected. However, these forms of life were easily recognizable as such, because they act much like already known life forms -- they exploit chemical energy sources, grow, and (most importantly) reproduce.

      I'm citing an extreme example, but my point is this: If there was life so extreme, how would we ever notice them?

      We probably wouldn't. But we also have no reason to expect that earthbound life is so terribly unusual, either. There might exist bizarre forms of life, but based on the single data point available concerning life in the universe (ourselves), it's not necessarily ridiculous to start looking for life "as we know it".

      How would we ever contact them? With radio signals embedded with decodable messages? You could broadcast a voice talking over FM radio into space, and when it reaches an alien race, they never notice it because either they've moved so far past that technology or never had the need to use radio-type waves for communication purposes.

      We might never be able to contact them in any meaningful way. However, that doesn't mean that we can have no knowledge that they exist. Even a highly advanced race would realise that RF technology is simple and robust for many applications, in much the same way that we on Earth still use lighthouses even though GPS is far superior and far more advanced.

      IMHO, the only point in looking for "inhabitable" planets is for future colonization. All else is simply pointless.

      I don't accept that it's "pointless" to do something simply because it's more complicated that we might first assume -- that's frankly a defeatist attitude. We have to start somewhere, and if life is not unusual, then our form of life is probably not unusual, so it makes perfect sense to look for what we understand as life. Furthermore, the importance of extraterrestrial life is such that finding it would probably have world-changing implications. Then we could start looking for the bizarre forms of life.

    • I've thought this for a long time. Scientists are looking for known life, in a way. Life based on carbon.. requires water, etc. I consider this shit. Look at startrek -- Voyager had an example of photonic life.. while this is an extreme example, it's one form of what could be that scientists don't even consider.

      Then, they said since no sun could get to the bottom of oceans. They said nothing could possibly survive down there... then they get there and see a completely independant ecosystem (I believe it is, anyway). They feed off shrimp, which feed off sulfur from geizers on the ocean floor. Another example of something scientists thought couldn't exist. We've been proven wrong so many times.. I think it's time to rethink our thoughts on requirements for life.

      Personally, I think it's just plain selfish to think earth contains the only (intelligent?) life in the universe.

      -DrkShadow
      • Probably this shrimp needs oxygen from the water and therefore technically can be considered part of a much larger ecosystem. A better example would be the ecosystems discovered in turkish caves which are for as far as I know (and I don't know it that far) not connected with any other ecosystems at all and not dependant on oxygen. Anyway; these ecosystems didn't start to exists independently; it were organisms from other ecosystems that have adapted to these ecosystems. So it isn't that far off to search for carbon-based water-requiring life; there's more to it than coincidence that the life on earth became carbon-based.
    • You seem to assume that the only research in this field is in looking for habitable worlds. You can safely assume that there are many other scientists around the world looking for all manner of strange things. Just like there are thousands of kooks looking for faces on Mars!

      The fact is that up until 7 years ago or so, it was _believed_ that there were NO other planets. (Due simply to the lack of proof) Now it's a huge task of reconsidering everything we thought we knew about planets and in particular their formation. This is the important result here, not hey this planet is close to the habitable zone, _maybe_ one of its moon's looks like Canada! The observation of so many different worlds has taught us a more than thousands of years of though on possibilities like what you mentioned.

      It's called science, and it's the only way we would discover any other sort of life or anything, be they gas dwelling, fusion dwelling, water dwelling!

      Keep laughing there, because you obviously dont get it.
      • maybe i misrepresented myself, or maybe you didnt get my point...

        I'm in no way condemning the search for life on other planets, the whole point of my rant was that we need to quit being so myopic in our search.

    • Because primitive "life" seems to have begun on Earth very early in its history and that life induces atmospheric changes that can be detected remotely, it does seem reasonable for scientists to develop methods to look for planets capable of supporting such life. The work by the OGLE team and telescopes being planned such as the Kepler Mission [nasa.gov] will identify planetary systems that more advanced telescopes, such as the Darwin Mission [rl.ac.uk] will be able to study for smaller planets that might show signs of primitive life. Simulations suggest that it is feasible for the gas giant planets to migrate into the near-stellar orbits being detected by the OGLE team without disrupting the orbits of planets in the habitable zone at least some of the time. It isn't unreasonable to look for life similar to that found on Earth because the elements on which it is based CHON are the most abundant in the galaxy. There is a much lower probability for life based on alternative chemistries. Given this perspective I think it is perfectly reasonable for scientists to attempt to put hard numbers on the f_p, n_e and f_l parameters of the Drake Equation [aeiveos.com].

      If assume that we understand most of the basic laws of physics and there isn't any possibility for "magic physics" such as subatomic engineering or faster-than-light travel, then one can predict what "advanced" intelligent technological civilizations may look like. At least some of them seem likely to be Matrioshka Brains [aeiveos.com]. These would be very difficult to detect using our current technology because they radiate heat at close to the cosmic microwave background temperature. To look for signs of advanced technological civilizations we will need to do infrared surveys [aeiveos.com], something that was suggested [aeiveos.com] by Freeman Dyson [aeiveos.com] more than 40 years ago.

      Another form they might take would be bacteria sized hive minds constructed using advanced molecular nanotechnology. In which case they could be all around us on Earth and we would never notice them. To look for those we need to start a program to develop highly parallel air, water and soil samplers that can detect micron and submicron sized bits of "technology".

      Free your mind -- the rest will follow.

    • IMHO, the only point in looking for "inhabitable" planets is for future colonization. All else is simply pointless.

      And just what about contacting them for the sake of communication and the advancement of both our civilizations? The Europeans a few centuries ago cared about the New World only for the purpose of colonization, and ignored the life that already existed therein. Do we really want to make the same mistake again? Have I been under the illusion that it is a quality of the human race that we are capable of learning from our mistakes?

      Those who do not remember history are doomed to repeat it.
      • again, to defend my point, I, in no way, said we should quit looking, i just said we should quit looking for other "us's"...by that i mean life forms similar to those on earth.

        Science tends to get a lot more subjective than it wants to be. We take for granted the notion that we are products of our culture (defined as broadly or as narrowly as you'd like), and that we, naturally as parts of a system, have a hard time thinking outside of that system to understand new and amazing things.

        Albert Einstein's discovery of the "warping" of space-time explained a problem that had been around for a while when it came to measuring the speed of light, up until he came upon his discovery, scientists had created the concept of a celestial "ether" (i'm not going to explain this, look it up)...the whole point is that when Albert came up with his idea, it revolutionized the way we even LOOK at the universe and opened up uncountless possibilities.

        Sadly, science does the same thing across the board. Look at our history of understanding the human body, and take into account the timeframe at which different theories came about, they were are all very ethnocentric for their time (ie, when the steam engine was the big thing, they thought the human body worked somewhat like a steam engine, etc)...even today we tend to think of the human brain as working like a digital computer, of course, we use that in metaphorical terms, but, in essence, what we are doing is limiting our thinking about a certain topic by likening it to something we understand more fully.

        Honestly, i believe the same thing is happening with the hunt for ET's...we *only* understand life as it evolved here, and when we go to hunt for ET's, we toss out the staggering odds against life ever evolving here, and blindly begin looking for life like us elsewhere (again, water/carbon based life, not just human).

        It just seems that we forget that life developing here was an unbelievable against-all-statistical-odds occurence...if that is so, why do expect the same kind of life to develop elsewhere?

        That's all i meant.

    • Yes, that's why SETI@Home is important (well, SETI in general). The microwave spectrum is a constant everywhere, so any intelligent life wanting to communicate at the speed of light will use EM waves, which can be detected by our radio telescopes.

      Unless, of course, everyone else figures out how subspace works (or its equivalent FTL) and we're looking in the wrong place :)

      On a technical note, I think it's the Hydrogen 13 band that is quietest in the EM spectrum, so presumably that's what another race would use to send a specific signal. BUT think about how many specific signals we've sent (one?) compared to how many incidental (every radio and TV broadcast since 1930 for example) transmissions we've made...

      Anyway, enough rambling.

  • Just a quick question: why do pulsar planets make our lives unhappy?
    • It's probably because they have yet to be properly explained, while still accounting for the very explosive solar transition that pulsars are believed to form under. He may have another reason, but the basic idea behind this is that the planets should be toasted in the initial creation of the pulsar. Yet, there they are, and they were discovered way back in 1990 or 91.

      josh

  • Multiply 42 by several thousand (Score:3, Informative)

    by Alsee ( 515537 ) on Saturday March 02, 2002 @08:36PM (#3099503) Homepage
    They were detecting these planets by watching for "transits", in other words eclipses. If you look at a star&planet from a random direction there is a VERY small chance that it will happen to line up exactly right to see an eclipse. I would estimate the chances as several thousand to one.

    With further analysis they can get a pretty solid multiplier for the number of unseen planets. These other planets must exist, and you now know something about them. In a sense they have indirectly measured many thousands of planets.

    Even without seeing them, the indirect knowledge about the other planets has scientific weight. This indirect measurement will be very useful in our understanding of other solar systems, how they are structured, and how they form.

    The scientific value of the 42 measurements carries a large multiplier.

    -
    • The scientific value of the 42 measurements carries a large multiplier.

      Yeah, but only after you hit the red, yellow, and green bumpers, and get two balls in the ball sink.
    • Yes, there is a relatively small chance of seeing a planet pass in front of a given star. In estimating how many systems have planets, which you just happened not to see, the most important quantities are average number of gas giants per system and the average distribution of those planets within the system. If most planetary systems are like ours, and the gas giants are relatively far from the star then it's rather unlikely to see a crossing. If on the other hand there are lots of places with gas giants near the star, then witnessing these events gets much more likely.

      I attempted to estimate the multiplier for unobserved planetary systems. If we only concern ourselves to star systems that are like our own (similar star size and 4 gas giants), then it's not hard to estimate how many systems you'd have to look at before seeing one crossing (during the period in question.

      I'll spare you the multiple integrals, but the result I got was that if gas giants are evenly distributed over the system then you'd see one crossing per 30 such stars under observation. On the other hand if they are confined to the outer solar system (as in our case), then you'd see only 1 crossing per 16000 stars.

      Depending on how many stars they were observing, this may well add to the case that many stars have gas giants much closer in than we do.
      • With further investigation that can determin how far these planets are from thier star. They say something to that effect in the article.

        I'll spare you the multiple integrals...

        Ouch. Please tell me you didn't just do a multiple integral? Knowing how to do calculus is good. Knowing how and not needing to is even better :)

        I just did a quicky calaculation and came up with about 1/2250 chance for Jupiter. More likely than I expected. Feel free to check my math/logic here...

        I clipped everything at 3 digits precision.
        Radius of Sun 4.33*10^5 miles
        Radius of Jupiter's orbit 4.88*10^8 miles

        Method:
        Confine all work to the surface of a sphere radius equal to Jupiter's orbit.
        Surface of this sphere is 4*Pi*R^2 = 2.99*10^18 SqMiles.

        Take an arbitrary equator on this sphere to be the orbit. Now widen this equator into a ribbon covering directions that get eclipsed. How wide? Take a rectangle one side is the diameter of the Sun, the other sides extend out to the orbit. Draw diagonals through the corners - these are the sighting lines. Opposite sides are equal. Width = diameter of Sun. (Radius of jupiter compared to the Sun falls into insignifigace in any case.) Again ignoring the negligable curvature, the area of this ribbon is (length*width) diameter of Jupiter's orbit * diameter of Sun = 1.33*10^15 SqMiles.

        The direction to the viewer will be a point on the sphere. What is the probability that this point lies on the ribbon? Area of ribbon / area of sphere = 4.44*10^-4. That is a 1 in 2250 chance.

        More likely than my original wild guess, and 7 times more likely than your figure. Any idea where the discrepancy comes from? Did I miss anything?

        -
        • I was trying to follow your work and instead I get diameter of Jupiter's orbit * diameter of Sun = 8.45*14 mi^2. The probability according to your method is about 2.8*10^(-4) or about 1 in 3500. Did I miss something?

          Your post inspired me to try a different calculation for the probability of seeing a distant sun's disk dimmed by a planet.

          Let:
          Rs = sun radius
          Dsp = distance from sun to planet (orbit radius)
          Rp = planet radius

          Draw the cone from the observer (apex) to the diameter of the distant sun. Neglecting curvature and using similar cones, the radius of the concial section intersecting the planet orbit is

          x = Rs * (Dop / Dos)

          where Dop (Dos) = distance from observer to planet (sun).

          The diameter of the disk = 2*(x + Rp).
          The area of the disk = pi * (x + Rp)^2.

          The areal fraction that the disk is of the orbital surface area = (x + Rp)^2 / (4*Dsp^2).

          Now assume: (1) the observer is far away from the sun-planet system, and (2) the planet size is much less than the orbital distance: then putting everything together,

          Probability = P ~ (Rs / Dsp)^2 / 4.

          Assuming
          Radius of Sun 4.33*10^5 miles
          Radius of Jupiter's orbit 4.88*10^8 miles,

          P ~ 1.97 * 10^(-7),

          or about a 1 in 5.1 million chance of seeing a dimming event, given these parameters, etc. This assumes that the observer can look in any direction and find a candidate solar system.

          If this calculation is right, I might have more hope of finding another planetary system than winning the state lottery ;-P

          • Your post inspired me to try a different calculation for the probability of seeing a distant sun's disk dimmed by a planet...

            Your math becomes much simpler if you throw out the cones. Observer is effectively at infinity.

            It looks like you worked out the chance of seeing the effect at a given instant. The scientists were watching all these stars for an extended period. I was working out the chance of ever being able to see a dimming event. That's why I used a ribbon around the orbit rather than the disk you used.

            I was trying to follow your work and instead I get diameter of Jupiter's orbit * diameter of Sun = 8.45*14 mi^2.

            You caught a combination of language error & missing factor of 2.

            I said:

            &GT Radius of Sun 4.33*10^5 miles
            &GT Radius of Jupiter's orbit 4.88*10^8 miles

            &GT (length*width) diameter of Jupiter's orbit * diameter of Sun = &GT 1.33*10^15 SqMiles.

            I *should* have said (length*width) circumference of Jupiter's orbit * diameter of Sun.

            The ribbon is as wide as the sun and wraps around jumpiters orbit. Circumference of Jupiter's orbit is 2*Pi*RadiusRadiusJupiterOrbit. Diameter of Sun is 2*RadiusOfSun:

            2*Pi*(4.88*10^8) * 2*(4.33*10^5) = 2.66^15 SqMiles for area of ribbon.

            Area of ribbon / area of sphere = 8.90*10^-4. That is a 1 in 1120 chance.

            Hmmm, that is almost exactly RadiusSun / RadiusOrbit. I bet it is exact and the difference is due to rounding errors. Makes sense, if they were equal the probability would be one.

            -
    • They were detecting these planets by watching for "transits", in other words eclipses. If you look at a star&planet from a random direction there is a VERY small chance that it will happen to line up exactly right to see an eclipse. I would estimate the chances as several thousand to one. On the other hand, it is impossible to tell these partial eclipses apart from reasonably stable sun spots, especially if the star is monitored for this brief period of time. Both decrease the star's apparent luminosity, and both would appear to circle the star.

      Worst-case scenario, there isn't a single real planet among the aberrations found using this method. Unlikely, but possible.

      • stable sun spots

        All 42 cases are multiple diming events. There were 4 more not included because the diming has not yet been observed to repeat. I believe a sunspot would generally orbit much faster than a planet. A sunspot would dim the star for almost 50% of the time. A planet would dim it for far less than 1% of the time.

        These 42 systems certianly deserve further observations to rule out other non-planetary explanations, but a stable sun spot seems like a rather implausible alternative.

        -

  • Re:Almost useful.... (Score:1, Funny)

    by Anonymous Coward
    LOL... correct me if I'm wrong, but don't "M-class planets" only exist in Star Trek?

    I don't think we actually have a system of planet classification, do we? I'm no astronomer, so any insight would be appreciated.

    Just goes to show how much Star Trek (among other SF shows, books, what have you) has influenced our lives.

  • We are alone. There may only be a handful of habitable planets in the entire Universe.

    • Other planets are still not habitable because what makes Earth habitable is more than its small size. For example, the Earth was larger but due to a rare collision the Moon was split off. Multiple moons or no moon is inadequate. Our single moon, and its size create unique seasonal and environmental conditions. There are other rare occurances, which when multiplied together, make alien human life non existent in our Universe.


    • So think now, of all near, discovered earth-like planets, how many had an unusual, rare collision with another planet of similar size of our Moon ? !

    Do the math! WE ARE ALONE !

    • This is exactly why "Martians" have been represented as little green men with big bug eyes for the last 50 years... Why are we only discussing the search for alien HUMAN life? Why would aliens (carbon-based or not) look like anything recognizable to us? For all we know, we've found some already and just didn't realize it. And as far as the "moon argument" goes, I don't think that it has as drastic an effect as you seem to claim. Are you saying that without the moon, Earth wouldn't be inhabitable? That's preposterous. The moon makes tides, werewolves, and not much else.
    • For example, the Earth was larger but due to a rare collision the Moon was split off. Multiple moons or no moon is inadequate. Our single moon, and its size create unique seasonal and environmental conditions. There are other rare occurances, which when multiplied together, make alien human life non existent in our Universe.

      I can't see what the moon or number of moons has do with the formation of life. The moon has no effect on seasons, they are caused by the the earth's axis of rotation being nonperpendicular to it's orbital plane. Even then, I can't see why seasons are essential for the formation of life. Seasons result in environmental conditions that oscillate over time, so an organism in an environment with seasons has to adapt to a greater number of conditions. Seasons seem to be a hindrance to survival, not an aid. Human life began near the equator, in a "low season" part of the world.

      FWIW, seasonal temperature and daylight changes are least extreme at the equator and most extreme at the poles. (People who move from, say, New York City to Miami often remark the days seen longer in the winter and shorter in the summer. Or vice-versa. Not too many other countries have a wide enough range of habitable latitudes to notice this effect.)

      • Tides (Score:2)

        by Rupert ( 28001 )
        I believe he's talking about tides.

        On a planet with only solar tides, the intertidal region where all the interesting sea-land evolution is happening is much smaller. I don't think it's necessarily *too* small, but it might take longer.
    • Then also think about the fact that we have found like what... less than 100 habitable planets out of many hundreds discovered. Then multiply that by basically millions for our galaxy. Then mulitply that by hundreds-of-thousands or more for all the galaxies in the known universe.

      Then take into consideration all the different types of life that exist. Bacteria, virii, air breathing, water breathing, weird little things that live at 2 miles below sea level in the oceans, crap that feeds of hot geysers, little buggers that live inside volcanoes, etc. Earth has so many different kinds of life. I think there is an extremely slim chance there is no life outside Earth.

      Just even europa, one of Jupiters moons, possibly has life within its oceans that they estimate to be as deep as 60 miles. I dunno about you but I would guess, somewhere out of the billions/trillions/quadrillions of rocks in space, there is life.

    • For example, the Earth was larger but due to a rare collision the Moon was split off.

      There is some merit in this view.

      However, it is not certain that tides were needed for the formation of life. Hydrothermal vents are a much more likely site for the origin of life, and unless you're on a world like Europa don't have much to do with tides. And don't forget the conquest of the land happened independently by insects, plants and amphibians. Can't be that hard now can it?

      The moon does assist in producing some interesting rhythms and aiding nocturnal animals. But I don't see why there can't be local replacements for these or even if they are needed.

      Another thing to remember all these planet surveys are sensitive to planets that strongly perturbe the star. That is, BIG planets close in ... or big planets in higly elliptic orbits etc. Not really conducive to finding earth like planets. Don't forget that the number of stars within a given distance of the Earth is about proportional to the cube of the distance (ignoring clusters etc) so within 100 light years there are 125 times as many stars are there within 20 light years (very approximately of course). So of all these thousands of nearby stars they have found 60 - 100 extreme systems. It proves that planets exist for sure, but we'll have to wait for the next generation of star searchers with optical searches for planets using spacebourne multiple telescope systems or whatever they're called.

      Pete

    • I think finding some scum under a rock somewhere out there on a cold barren planetoid would be just as significant as finding an intelligent civilization. Granted the latter would make a more exciting feature at the box office.

      I am also reminded of the Drake equation, that even with very conservative estimates of the number of planets meeting the conditions for an Earth-like environment, taking into account all of the factors that you mention, the number still comes out to at least many thousands. It is a very large universe out there, and I would bet that somewhere there's a being wondering if he (or it) is alone, just as we are.

      I wonder if they have that first post problem too.

    • i think that the formation of the moon is one of the least important earth oddities that helped in the formation of necessary conditions for life, although it was fairly important. For example:
      • if life hadn't formed when it did (and became aerobic when it did) earth would have become a greenhouse planet similar to venus, making the formation of life almost impossible.
      • second, it has taken close to 4 billion years since life was formed on earth to become civilized. this is longer than the expected lifetimes of the majority of stars in the universe.
      • third, a second or third generation star is required for the formation of heavy enough elements for non-gas giant planets. A large number of stars with long enough lifetimes for the formation of life are still first generation stars.

      the list goes on and on. however, i think that this doesn't rule out inhabited planets, it just makes them somewhat rare compared to the number of gas giants.
      • (* second, it has taken close to 4 billion years since life was formed on earth to become civilized. this is longer than the expected lifetimes of the majority of stars in the universe. *)

        I don't think this is true. Quantity-wise, most stars are even smaller than the sun, and probably burn longer because of that. However, at that size they tend to be more variable (unpredictable) in their energy output IIRC.

        BTW, it is speculated that our sun will start to heat up enough to disturb Earth's living conditions in about 500 million more years. IOW, the sun is nearing its retirement years.
    • Life is not nearly as limited as that. Tides are not essential to the formation of life. Life can also spread from one solar system to the next.
      There are 100 Billion stars in the milky way and 200 known galaxies in the "Known" universe. Most of the galaxies we can see from the earth are vastly larger -- and vastly older than any star in our galaxy.
      Would you like to do the math then? 20 trillion stars in the known universe alone. Evidence supporting that most systems have jovian size planets. Hypothesis that any system with so many jovian systems formed similarly to our own and would have earth style planets. Now, given that what if there were say 2 trillion earth style planetoids in the "Known" universe? Most would be more like Mars or Venus than earth. Say only 5% are M-class. That leaves some 100 billion M-class planets in the Universe. If only 5% of all M-class planets acquire life, either through intra-solar system cross infection, or else through random chance encounters that lead to the formation of DNA based carbon lifeforms. That would leave some 2 billion planets where life developed. Statistically at least 10 million of those would be in our own galaxy.
      That's pretty a pretty high number, but all the evidence is pointing towards that optimistic presumption about the development of life.
      Oh but don't get your hopes up about meeting aliens because we're in the the equivalent of the backwoods as far as our own galaxy is concerned. there is hardly a sun within 5 light years of us, much less solar systems where life could develop.
      On average our solarsystem has a star density 25 stars within one square lightyear.
      Considering the age of the universe, and the size and scope of it there is no doubt that there was other life out there. However we'd be lucky if our nearest neighbor was within a 2000 light year radius. Star Trek is purely fiction and we'll never see anything remotely like the federation.
      That doesn't mean we're 'alone' in this universe.
    • Our single moon, and its size create unique seasonal and environmental conditions. There are other rare occurances, which when multiplied together, make alien human life non existent in our Universe.

      That's not valid logic. Let me sum up your logic for you:

      --There is life on earth (true)
      --Life on earth was influenced by a number of complex conditions (true)
      --Therefore, life can only exist on Earth or planets exactly like earth

      That doesn't make any sense whatsoever. That's like saying "bananas are yellow, and we can eat bananas, therefore nothing in the world is edible unless it is yellow."

      In fact, there may be complex conditions at other planets with intelligent life, and if they came to Earth, they'd wonder how life ever formed on earth without the same conditions the aliens had on their planet.

  • David Spergel's new telescope lens (Score:3, Interesting)

    by juju2112 ( 215107 ) on Saturday March 02, 2002 @09:03PM (#3099563)
    I read an article in the last issue of Discover magazine about a breakthrough telescope design that could let NASA see much smaller planets.


    The best part about it is that it's a cheap solution -- you just add this weird "cat's-eye" type lens onto a normal telescope. This deflects all the light from the center of the frame away, but allows the light on the side of from to come in. This way, the light of the much brighter nearby star won't block out the smaller planet.


    The Discovery article was pretty cool. This is the only equivalent I could find online.. Unfortunately it doesn't go into as much detail.


    http://www.princeton.edu/pr/pwb/01/0416/6a.shtml [princeton.edu]

  • The perfect number (Score:1, Redundant)

    by Asparfame ( 96993 )
    42... I bet they stopped once they got there intentionally as an allusion to the late great Adams.

  • Is anyone really surprised by this? (Score:3, Insightful)

    by Beautyon ( 214567 ) on Saturday March 02, 2002 @09:25PM (#3099608) Homepage
    Its amazing that anyone is surprised by the "discovery" of planets around other stars.

    Direct obersrervation of these bodies is interesting and exiting, but only because we are finally getting to see directly what most intelligent people already knew was there with absolute certainty, and not because its actually sometheing unexpected.

    It would be utterly incredible if there were NO planetary bodies orbiting other stars; now THAT would be a scoop.

    The fact that they are finding them so quickly is merely a funciton of having better equipment. You would expect to find more planets with better telescopes, and when they finally put a very big telescope on the dark side of the moon, or launch some other new excellent device, all the smaller bodies will suddely resolve out of the glare.

    What I find truely beautiful is the range of unimagined objects that the hubble keeps uncovering week upon week. Like this stuff [stsci.edu].
  • If most of them are uninhabitable, do you mean to say that some are?

    Or is it just some lose adjective thrown in for editorial purposes without thought to what it really means.
  • because at the rate that things are going over here, we will need a place to go and restart Society in about 10 years.
    • (* because at the rate that things are going over here, we will need a place to go and restart Society in about 10 years. *)

      I think this is an important point because there is kinda a "Moores Law of Terrorism" where the number of people a few terrorists can kill doubles every X years. It seems only innevitable that terrorists will be able to wipe out the entire planet in the not too distant future. Time to spread our eggs before the basket is blasted.

  • I was intrigued to hear about the strong radiation that blankets Jupiter's moons. Those would have been the closest place to look for life outside of earth. I forget the reference, but it turned out that Jupiter's massive auroras create too severe of a radiation field for life to exist, at least as we know it. But who knows, maybe some form of life has adapted to extreme radiation. After all, some alien could say the same about earth, until he saw that the earthlings skin tans in the sun :)
  • ... that none of the trolls have made an OGLE team / heavenly bodies / Aria Giovanni post yet.
  • Our technology developes to the point where we can focus on the alien ships landing on the other planets or orbiting them? Or maybe catch one traveling through space! :)
  • My original reply was more of enthusiasm then accuracy however, I do stand corrected. You are correct when it comes to using Doppler efects to measure bodies in motion, particularly 2 bodies in orbit around each other. I realised later that I had used the wrong term to decribe what was in my minds eye. The term I should have used, was Astrometry.

    Astrometry, is used to determine the proper motion of a star, using other stars as reference points. If a body is revolving around a star then the body will affect the circular motion of the star. As one measures the stars linear motion, it will be found that the motion is not in a straight line, but rather in a wobbly line due to the presence of a planet or planets revolving around the star. This situation is similar to observing a person spinning a shotput around his or her body. The person shows a wobbling type motion due to the heavy load that is being rotated about his or her body. The person represents the star while the shotput represents a planet. In addition, the person can move from point A to point B while the shotput is revolving. Therefore, there are two motions, the wobbly motion caused by the rotation of the shotput, and the linear motion caused by the movement of the person. If the person was not rotating a shotput and simply walking, then the only motion observed would be the distance from point A to point B, and no wobble in the motion would occur. This, of course, presupposes that the person is sober. In like manner, if one were to observe the proper motion of a star without any planets revolving about it, then the distance the star moves from point A to point B would not reflect a wobbling motion, the motion would be in a straight line.

    Radial velocity, which is measured by the doppler effect (lines in the stars spectrum) takes into account the line-of-sight velocity; i.e. the velocity of which a star is moving towards or away from us. If the light from the star is moving towards us then the spectrum of the star will be shifted to the blue portion of the spectrum (blueshift) and the velocity would be negative. If, on the other hand, the star is moving away from us then the spectrum of the star will be shifted to the red portion of the spectrum (redshift) and the velocity will be positive. By observing the spectral shift one can determine the rate at which the star is moving.

    How does this relate to the detection of planetary bodies revolving around stars? If a planet or planets revolve around a star then the motion of the star will be affected. According to Alan Boss, writing in Physics Today, if a star is orbiting around the center mass of a system, then it suggests a planetary body or bodies revolving about it. More to the point, if the above is true then there would be a periodic shift in the doppler velocity. This is the star's spectrum would exhibit a shift to the red and then to the blue, and then to the red, periodically. In other words, the effect of planetary bodies around a star will affect the radial velocity of the star so that it would be moving towards us and then away from us, and continue to repeat that pattern. It should be noted that the perturbation or doppler velocity shift is very small, and therefore, extremely difficult to detect.

    Many of the ensuing discoveries rely heavily upon radial velocity techniques. Highly specialized spectrographs, that can detect tiny doppler-induced wavelength shifts in a star's spectra are used to calculate the radial velocities. However, it will be of no surprise to note that the planets that were discovered using this technique are large and/or are in tight orbits, because this technique disposes itself to that type of finding.

    The direct imaging method is based on the fact that planets reflect the stars' light. Planets do not give off any light of their own. For example, the various planets we see in the night sky are a result of the sun's light reflecting from them. Likewise, planets around other suns would also reflect the light of their suns. This method is used in order to determine reflected light from an extrasolar planet. It is obvious that only extremely large planets may be detected using this method. The major problem with this technique is that the star is much brighter than the planet it illuminates, and can tend to obfuscate it.

    Photometry can be used to detect a change in the brightness of a star, as in the case when a planet occults a star. On Earth we can observe this during a solar eclipse. That is, our Earth occults our Sun during an eclipse. As an extrasolar planet revolves about its star, it will pass between its star and the line of sight as seen from the Earth. A change in the brightness of the star due to this transit would then suggest a planetary body.

    Earth sized bodies would indeed be almost invisible to Dopler shift searches, but developments are are already well underway to correct this problem. I have submitted a post on this subject,mostly consisting of links, but I am still waiting for it to be authorized. If it should be declined, I will write something up on it in a reply to this post for the sake of discussion.

    • As I said earlier, I don't expect we'll ever find Earths with Doppler techniques. The spectral lines in the stars are broadened by the activity on the stellar surfaces by more than the amount of the shifts due to planets. This makes it extraordinarily difficult to pick out the planet's effects.

      Astrometery probably won't help much, either, as long as the point-spread function of the telescopes blurs out the star's light by well more than the amount that the stars move. Even without that effect, it's tricky. I spent a summer doing astrometry. You have to do it differentially (relative to nearby objects) rather than absolutely (position on the sky) because exact positions are too imprecise. But even that was tough, given all of the instrumental and atmospheric effects.
  • Recently though, the OGLE team has come up with more than 42 new candidates.

    so... what? 43?
  • This is a repost of an error that was pointed out to me in an earlier reply I made. This isn't an attempt at spam, just an attempt to help clear up a mistake on my part, but moreso, to make better known, what I feel is good and informatave reading.

    My original reply was more of enthusiasm then accuracy however, I do stand corrected. You are correct when it comes to using Doppler efects to measure bodies in motion, particularly 2 bodies in orbit around each other. I realised later that I had used the wrong term to decribe what was in my minds eye. The term I should have used, was Astrometry.

    Astrometry, is used to determine the proper motion of a star, using other stars as reference points. If a body is revolving around a star then the body will affect the circular motion of the star. As one measures the stars linear motion, it will be found that the motion is not in a straight line, but rather in a wobbly line due to the presence of a planet or planets revolving around the star. This situation is similar to observing a person spinning a shotput around his or her body. The person shows a wobbling type motion due to the heavy load that is being rotated about his or her body. The person represents the star while the shotput represents a planet. In addition, the person can move from point A to point B while the shotput is revolving. Therefore, there are two motions, the wobbly motion caused by the rotation of the shotput, and the linear motion caused by the movement of the person. If the person was not rotating a shotput and simply walking, then the only motion observed would be the distance from point A to point B, and no wobble in the motion would occur. This, of course, presupposes that the person is sober. In like manner, if one were to observe the proper motion of a star without any planets revolving about it, then the distance the star moves from point A to point B would not reflect a wobbling motion, the motion would be in a straight line.

    Radial velocity, which is measured by the doppler effect (lines in the stars spectrum) takes into account the line-of-sight velocity; i.e. the velocity of which a star is moving towards or away from us. If the light from the star is moving towards us then the spectrum of the star will be shifted to the blue portion of the spectrum (blueshift) and the velocity would be negative. If, on the other hand, the star is moving away from us then the spectrum of the star will be shifted to the red portion of the spectrum (redshift) and the velocity will be positive. By observing the spectral shift one can determine the rate at which the star is moving.

    How does this relate to the detection of planetary bodies revolving around stars? If a planet or planets revolve around a star then the motion of the star will be affected. According to Alan Boss, writing in Physics Today, if a star is orbiting around the center mass of a system, then it suggests a planetary body or bodies revolving about it. More to the point, if the above is true then there would be a periodic shift in the doppler velocity. This is the star's spectrum would exhibit a shift to the red and then to the blue, and then to the red, periodically. In other words, the effect of planetary bodies around a star will affect the radial velocity of the star so that it would be moving towards us and then away from us, and continue to repeat that pattern. It should be noted that the perturbation or doppler velocity shift is very small, and therefore, extremely difficult to detect.

    Many of the ensuing discoveries rely heavily upon radial velocity techniques. Highly specialized spectrographs, that can detect tiny doppler-induced wavelength shifts in a star's spectra are used to calculate the radial velocities. However, it will be of no surprise to note that the planets that were discovered using this technique are large and/or are in tight orbits, because this technique disposes itself to that type of finding.

    The direct imaging method is based on the fact that planets reflect the stars' light. Planets do not give off any light of their own. For example, the various planets we see in the night sky are a result of the sun's light reflecting from them. Likewise, planets around other suns would also reflect the light of their suns. This method is used in order to determine reflected light from an extrasolar planet. It is obvious that only extremely large planets may be detected using this method. The major problem with this technique is that the star is much brighter than the planet it illuminates, and can tend to obfuscate it.

    Photometry can be used to detect a change in the brightness of a star, as in the case when a planet occults a star. On Earth we can observe this during a solar eclipse. That is, our Earth occults our Sun during an eclipse. As an extrasolar planet revolves about its star, it will pass between its star and the line of sight as seen from the Earth. A change in the brightness of the star due to this transit would then suggest a planetary body.

    Earth sized bodies would indeed be almost invisible to Dopler shift searches, but developments are are already well underway to correct this problem. I have submitted a post on this subject,mostly consisting of links, but I am still waiting for it to be authorized. If it should be declined, I will write something up on it in a reply to this post for the sake of discussion.

  • What about IPv6 [slashdot.org]? With all these planets, will there be enough address space available?
  • The thought of life on other planets is something truly frightening, not because of those life forms but because of humanity itself. We have enough trouble dealing with members of our own species who are of different ethnicity, race, religion or creed.
    humanity needs to take a long hard look at itself before we can look into space. I fully support the space program, and believe it deserves more funding for manned missions back to the moon, and a mission before 2010 to mars. But are we ready to meet extra terrestrial life? I would say after looking at the last few years of world history that we are not.
    Mankind as a whole (not the geek population, and perhaps not anyone reading here, as geeks tend to be more open minded than the rest of society (again a stereotype)). is not ready, this is a truly sad statement, as it betrays the limitations of our species, and the blind bigotry with which we view anything different.
    Keep looking guys, I believe there is life out there, I just hope we're ready for it when we find it, or it finds us...
  • The current method is only suitable for huge (multiple Jupiter size) and fast planets. Thats because it uses doppler shifts to look for slight gravity frequency shifts from stars. The shift must be fast and big.

    Space-based methods promise more sensitivity and proposals are in the works.

    An alternative method is the light curve method that looks for planetary eclipses of edge-on systems. This has only generated a couple candidates. The already-approved space mission Kuiper will watch the same patch of sky of five years continuously for rare planetary eclipses. It has a 350 megapixel imaging array (42 x 8 megapixals). This could detect earth-size planets.

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