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First small planet found outside our solar system 169

Posted by Hemos
from the it's-like-the-earth-baby dept.
jrb writes "For the first time, a small planet (i.e. non-gas giant sized) has potentially been found outside the solar system, helped by a gravitational lensing effect that magnified it. The BBC is carrying the full story. "
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First small planet found outside our solar system

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  • I'm not sure whats funnier, the original post or this :)
  • by jflynn (61543) on Monday September 13, 1999 @11:09PM (#1683785)
    Science is inductive. A theory is proposed, then grows in acceptance as a large body of data is found to agree with the theory, while none is found that contradicts it.

    We've had theories of solar system evolution, planetary spacing, formation of asteroid belts, and others, for a long time. But these theories are very unsatisfying because we only have one datapoint, our own solar system.

    This may not seem important, if you believe that the solar system is completely typical. By the nature of a bell curve, most likely our system is in most respects. But there is very little evidence it is yet. We were already pretty certain that gas giant planets are not uncommon. This is the very first evidence that small rocky planets may not be uncommon either.

    According to my calculations the feat is very roughly equivalent to detecting a speck one micrometer in radius at a distance of two kilometers, so I'm impressed anyway.
  • I was curious about this one, since I don't recall any mention of an earth-sized planet at the July AAS meeting on gravitational lensing. Still, I work on cosmological gravitational lensing, not microlensing, so perhaps I came down with a case of tunnel vision at the conference.


    Running this one down took a little leg work, seeing as how the BBC did not elect to give the names of the researchers involved. As best I can tell the BBC has mixed up two separate lensing events. The paper that appears to have triggered the story is probably this paper on MACHO-97-BLG-41 [lanl.gov], since that is the most recent paper claiming a gravitational lensing planet detection. However, that paper is about a 3-Jupiter mass planet orbiting a binary star system, an interesting find, to be sure, but a far cry from an earth-sized planet. So, even if that is the article the BBC is responding to, it's not the one they're talking about.


    The article mentions that the event was observed in 1998 and involved an earth-sized planet, so that sounds suspiciously like MACHO-98-BLG-35 [lanl.gov], but that paper came out (as a preprint) back in May, and it was announced at the January AAS meeting, so it's a little surprising to see a news article on it just now, unless it's just now appearing in the journals.


    Anyhow, assuming the event is 98-BLG-35, there's more to the story. The PLANET collaboration [astro.rug.nl] also monitored this event, and they found no evidence of a planet [astro.rug.nl] in this system. As far as I know, the status of this system is still under dispute. Unless some problem has been found with PLANET's data, I think it's a little early to claim that an earthlike planet has been detected.


    To get the scoop on microlensing, its application in planet searches, and the other things we can learn from it, I recommend PLANET's web page [astro.rug.nl]. Among other things, they talk about why microlensing is more sensitive than radial velocity studies (the technique that has produced most of the other extrasolar planet detections) to planets in star systems similar to our own solar system.


    -r

  • The thing is, to generate RF you not only need intelligence, you need a tool-user. A small social carnivore/omnivore will probably be (reasonably) likely to become intelligent. But if it's limbs are specialized for some purpose not readily adaptible for "manipulation" (e.g., running [hooves] or prey capture [claws]) then tool use may never develop, although an extensive oral tradition might. Language and tool-use are independant in genesis, although, of course, there is a feedback relationship between them. If coyotes had developed a full language before people showed up, then people would never have showed up.
  • I'm not sure how frying each of the individual dust grains orbiting the Sun at that stage is supposed to affect planetary formation. You'd just have molten dust grains in the same orbits (with perhaps some random perturbations from volatiles venting off, but then there were going to be random perturbations anyway, from mutual gravitation and the occasional other star passing within a few thousand AU). They'd cool off again in an eyeblink compared to the average time between collisions (so it's not a matter of sticking together while molten).

    So what gives?
    /.

  • Just be careful here. The weak form of the Anthropic principle is sound, but the strong form is fallacious. Unfortunately folk sometimes start at the weak one and slide over into the strong one. This can lead to some choice zaniness, but also to less desireable outcomes.

    To epitomize:
    The weak form: If we weren't here, we wouldn't see it.
    The strong form: So it must be designed for us.

    It can be very difficult to tell when one is switching back and forth from one to the other. See the Gaia theory for a strong example of this. Even when you are watching for it, you aren't always sure when the changeover happens. But eventually you can reach a point where you can say: "Ok, this is extending the perfectly valid initial precept too far"


  • The link given was bogus (I think J05H was trying to make it pop up in a new window and /. mangled the link tag). The correct link is here [obspm.fr] (in France), with a French version [obspm.fr] pour les francophones, and a US mirror [harvard.edu] for those of us on this side of the pond.

  • Sorry to just be nit-picking, but to an educated person, with access to the right literature, it was pretty obvious. They also didn't have the scientific method back then.
  • bah. Until someone figures out how to make a whole buttload of money within one fiscal quarter by doing all that, it's probably not going to happen. Not with our insectoid species.

    "The number of suckers born each minute doubles every 18 months."
  • Sure they would. As an example of how NOT to run things.

    And, of course, for the slapstick comedic value.

    "The number of suckers born each minute doubles every 18 months."
  • "but since the nearest star is 8 (10? lets call it 8) light years away"

    Let's call it 4.3 ly

  • I was dissapointed, though, that the article missed any mention of just how far away this new planet is, and perhaps how far it would take to reach it using conventional space travel. Or better still, how likely it is to be Earth-like in ways that might make it colonisable if we were ever able to reach it...
    1. How far away - you're right they should have mentioned this
    2. How far [long?] it would take to reach it - you can do the math yourself....very very long time seeing as the nearest star is 3.4 light years away and we're travelling at a tiny fraction of the speed of light 3. How likely it would be Earth-like - give me a break...they can barele tell the planet is even there. They'd need to know chemical make up to tell that.

  • You'll be holding your breath for a long time considering we don't even have pictures of pluto's surface yet unless you count this. [nasa.gov] I have a lot more faith in a reputable scientists explanation for gravitational anomaly and such than what most people think they've seen with their eyes. To an astronomer this is seeing, though it may seem unconventional to some people. The human eye is just a sensor that happens to operate in the range of wavelengths we call visible light. A film used in an X-ray is a sensor that detects energy not visible to the human eye. Most people don't doubt doctors interpretations of X-rays. We even except more estoric sensing systems such as magnetic resonance imaging where things are mapped non-linearily into a range of colours. Given that the average doctor is much less rigorous than the average astronomer it shouldn't be much of a leap of faith to at least accept that there is a good chance that the object is a non-gas-giant planet orbiting a star.

  • Not to piss all over your point (with which I agree in principle), but Eratosthenes calculated the diameter of the Earth to within 1% over 2000 years ago.
    Also, today's technology is ridiculously superior to anything we had even ten years ago. All this instrumentation means more data, and the more data we have the more it seems implausible that we're on the only habitable planet in the galaxy, let alone the universe.
    Then, of course, there's the definition of 'habitable'. Has Star Trek taught us nothing? Life probably doesn't need yellow dwarf stars with rocky planets 150M km away.
  • by Shin Dig (27213) on Monday September 13, 1999 @11:10PM (#1683799) Homepage

    Just trying to wrap up some points that were being put out here, and maybe answer some questions in the meantime with my intermediate knowledge of astronomy.

    1. Finding this planet, if the evidence leans towards that theory, is a big deal, as so far all we have found arround other systems are very big gas giants. One solar system is really bad for statistical analysis. We could be the fluke of the universe, so just because it happened here doesn't mean it had to happen somewhere else.
    2. Nearly all planet observations, an really all astronomical observations, are objects infered by the bizare behavior of well lit objects. Faint changes in spectrum of a single bright object, means that it is probably a binary system... etc. The best analogy I have heard about astronomy is a goldfish trying to figure out what the world outside its pond is like. It can never go there, but can learn from indirect observations.
    3. I assume that the gravity lensing difference between the two stars can easily be picked out because although they both throw a lot of light, they don't have the same spectrum, and probably not even the same redshift. You can then subtract out the closer star because you very carefully observed it when there was nothing significant behind it.

    I don't claim to be an expert on such issues, but hopefully someone got something from my little rant here.

  • Or better still, how likely it is to be Earth-like in ways that might make it colonisable if we were ever able to reach it...

    What is wrong with you people? You make me think the dude in "The Matrix" was right: we're just like a virus.. destroying everything around and then spreading further.

    Why the hell do you want to colonise everything? Isn't it a better idea to stop polluting our own planet? Stop wasting its resources so rapidly?

    Gee, and they picture aliens as evil in those shitty american movies.
  • Come on, everybody knows the earth is flat and travels through space on the back of a giant turtle (Great A'Tuin), carried by four giant elephants.

    pffffff.
  • Light doesn't have mass. It's just that a
    huge massive object (planet) bends space-time
    around it, so when light travels in its own
    straight line, it follows a curved space-time.

    Think of a large sheet on which you place a
    heavy bowling ball. It'll sag the sheet in
    where it is resting. If you then try to
    roll a small ball on the sruface of the sheet,
    it'll bend around where the bowling ball is.
    In the reference frame of the smaller ball
    it IS following a straight line, but in the
    frame of the bowling ball, it's curving.
    Weird, eh?

    Photons are weird things. They can act as
    waves and as particles. Don't think about it
    too much without the proper amount of
    caffeine...
  • >Light has mass, not much, but some, so any
    >sufficently massive object can bend light
    >perceptibly.

    Err, what? Light has mass? I want to know what you're smoking, 'cause I want some too.

    Light does not have mass. Gravity affects both matter and radiation. This is how, theoretically, black holes work.
  • If the planet is the home of Steve Jobs, then it will have an eccentricity in its orbit, due to the necessity of having the whole planet revolve around Jobs rather than vice versa.

    jsm
  • If you had extensive physics (any freshman college course for example) you would know that heavy objects do in fact fall faster in a vacuum. (In air you get into wind resestance trouble) However the other variables overshadow this for any object you could reasonably test. (on earth those variables are more or less constant, except for the difference in mass. But objects smaller than say the moon tend to be the same mass for all practical purposes)

  • Even if the universe DID have tons of intelligent life and advanced civilizations floating around up there, we'd still be a fluke.

    It's a big, big, big universe. I'll give it that.

    "The number of suckers born each minute doubles every 18 months."
  • by Anonymous Coward
    If things had gone a little differently, I might have done my doctorate on this project.

    These comments are pretty good except the distance is way out - the background stars are in the galactic bulge (about 8.5 kpc (=28000 lt yr) away.)

    I was briefly involved in this project a few years back, and visited the observatory once before regular observations got underway. The telescope used is a 0.6m reflector. At that time, the camera controller computer was a rack-mounted Sun. The telescope control computer was MS-DOS (this system was 'inherited' from the observatory.) I installed Linux on two computers for use in preliminary inspection of images and data processing (using the IRAF package.)

    Unfortunately, I don't remember the details of what you can figure out from the lensing light curves. There are three parameters to a normal lensing event: mass of the lens, impact parameter (how close the lens gets to the line of sight to the background star) and the transverse velocity of the lens. I think there are only two parameters measurable from the lensing (amplification and duration) so the lensing parameters cannot be fully specified. (In this case, we have a superposition of two lensing events - one from the star, one from the planet.)

    I have found an abstract (from an AAS meeting) on line for this discovery, but not the full journal article: http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bi bcode=1998AAS...19310805R&db_key=AST&hig h=37debb66ed03833

    See also Stupendous Man's posting - he knows what he is talking about.

  • When the first "possible" Sun was found out side out solar System (sol), there was all this excitment about "at last, planets exist". We are just living in a normal planet, in a normal solar system. sometimes i wonder, "why is it so hard for people to think there could be life out there, or other planets". People make a big joke about aliens - why? do they think we are so special? Why do they think we are so special that we are the only living things? Totally closed minded. You get these "sciencists" saying, "water doesn't exist" or "life on earth is unique because the odds against are so great". The odds may be small, but the universe is a damned big place.. These people are just soo closed minded its unreal... Its like they don't have the comprenshion of "other life, other planets". We may not have had the technology to find planets, to find life, but doesn't mean they don't exist does it!!! Throughout history humans have been incorrect, because we seem to be so self centred, for example: the Sun goes around the earth! There are no other planets but our own There is only one God for humans We are living on the only inhabited planet Earth is the only planet with water Humans are some how special, since we are the only intelligent living animals animals don't have feeling / intelligence, only humans do etc etc etc and it goes on.. Erm, humans have always been self centred, so this isn't a very suprising view. Also you get these people saying "but any aliens wouldn't have had the time to develop such technology", basing their views on our time on this planet. Remember, before us there were the dinosaurs. IF humans had been around instead of the dinosaurs, and survived the big bang, just image how intelligent we would be now? This could be the case for any alien life.. Also, Alien life could have formed on planet millions of years before life existed on this Earth. These people will be proved wrong, and it will be like billy boy saying "never need more than 640K", or "the world is flat"!! There are lots of solar systems with lots of Suns, and around them exist lots of planets, with water, with life - some will have "intelligent" life others not. You shouldn't be surprised when other suns, planets, water, and eventually life are found. Its obvious that these exist - its just we don't have the technology...
  • it would be really really cool if the could find out more about all these planets they are finding...
    right now all they can tell is mass (and from that, size) and dimensions of it's orbit...

    and an even better question, is anyone pointing radio telescopes at these flying rocks?
  • When the first "possible" Sun was found out side out solar System (sol), there was all this excitment about "at last, planets exist". We are just living in a normal planet, in a normal solar system. sometimes i wonder, "why is it so hard for people to think there could be life out there, or other planets". People make a big joke about aliens - why? do they think we are so special? Why do they think we are so special that we are the only living things? Totally closed minded. You get these "sciencists" saying, "water doesn't exist" or "life on earth is unique because the odds against are so great". The odds may be small, but the universe is a damned big place.. These people are just soo closed minded its unreal... Its like they don't have the comprenshion of "other life, other planets". We may not have had the technology to find planets, to find life, but doesn't mean they don't exist does it!!! Throughout history humans have been incorrect, because we seem to be so self centred, for example: the Sun goes around the earth! There are no other planets but our own There is only one God for humans We are living on the only inhabited planet Earth is the only planet with water Humans are some how special, since we are the only intelligent living animals animals don't have feeling / intelligence, only humans do etc etc etc and it goes on.. Erm, humans have always been self centred, so this isn't a very suprising view. Also you get these people saying "but any aliens wouldn't have had the time to develop such technology", basing their views on our time on this planet. Remember, before us there were the dinosaurs. IF humans had been around instead of the dinosaurs, and survived the big bang, just image how intelligent we would be now? This could be the case for any alien life.. Also, Alien life could have formed on planet millions of years before life existed on this Earth. These people will be proved wrong, and it will be like billy boy saying "never need more than 640K", or "the world is flat"!! There are lots of solar systems with lots of Suns, and around them exist lots of planets, with water, with life - some will have "intelligent" life others not. You shouldn't be surprised when other suns, planets, water, and eventually life are found. Its obvious that these exist - its just we don't have the technology...
  • I don't understand why people make such a fuss about finding planets. Sure it's nice to have scientific hard evidence that they are there.. but was there ever any real doubt as to the existance of planets outside our solar system?

    I mean, come on people! Apply a little logic here: it's a BIG UNIVERSE.. there *has* to be more out there than what we have in our little SS.

    Let's not be naive about this.
    --
  • Actually there are sulfur based life forms on earth that live around hot smokers at obscene depths on the ocean floor. They're tubeworms and clams and such so it doesn't say much about whether you could have a sulfur based skeletal system. One thing it does say though, is life can exist in places extremely inhospitable from our point of view
  • Religion is often a convenient excuse for those in power to wield such power arbitrarily. I don't think that the absense of religion would buy humanity much in the way of compassionate or enlightened leadership. It would only cause tyrants to look for more convenient excuses - or at least that's the gist of what Stalin's rule seems to indicate.

    It's kind of sad, actually, that a belief system takes the rap for despicable acts. Again, all Christians are blamed for The Inquisition.

    As a Christian (with slightly heretical beliefs, which would have probably earned me a date with a hot stake a scant few hundred years ago), I see nothing in the Bible that explicitly says that the divine design of humanity precludes the possible existance of intelligent extraterrestrial life (therefore, I believe in the possibility). The fact is, a few ultra-conservative fundamentalists have publicly wringed their hands over the possibility that there is intelligent extraterrestrial life, and the possibility that they might not worship God, or may even end up being THE minions of satan himself, but I don't think that most Christians believe thusly. Though there are a lot of sheep out there, who listen to these televangelists. The way I figure, when we see aliens, we'll know they exist. Until that day (or until Hillary Clinton fesses up), all we can do is either believe in the possibility, or (wrongly) believe that there IS no possibility. (wrongly, because it's a BIG universe, and we haven't seen it all yet, so it's impossible to draw that conclusion). When/if we DO ever encounter them, we'll know at that time if they have a religion, or a culture, or even a language, and whether they know how to make good pizza (which is what I'm primarily concerned about).


    "The number of suckers born each minute doubles every 18 months."
  • Just cause most of us (and i'd say all of us that are intelligent) find the existance of extrasolartary planets realistic - doesn't mean we shouldn't be looking for them.
    Finding them is just like finding more evidence for evolution - it's obvious - but it's nice to be reminded how right we are :)
  • It IS

    therefore is runs BeOS
  • You are almost right. What you (and everbody else in the above list) are forgetting is Newton's 2nd(?) law: for every action, there is an equal and opposite reaction. Yes, the absolute accelleration of an object in a gravity field is independent of its mass, but its accelleration relative to the body creating the gravity field is not due to the object accellerating the body towards it at the same time.

    The relative accelleration (ie the rate the object appears to be falling, or the rate of approach) is givven by a=G(m1+m2)/(d*d). Here's the proof:

    f1=G*m1*m2/(d*d) -> a1=f1/m1=G*m2/(d*d)

    f2=G*m1*m2/(d*d) -> a2=f2/m2=G*m1/(d*d)

    a=a1+a2 = G*m2/(d*d) + G*m1/(d*d) = G*(m1+m2)/(d*d)

    NOTE: The directions of the two absolute accellerations are opposite to each other (unit(a1)=-unit(a2)) so as relative accellaration is a1-a2 (or a2-a1), the magnitude of the relative accelleration is mag(a1)+mag(a2) and we couldn't care less about the direction.

    In conclution, the mass of an object does affect its rate of fall, but when we're talking about the moon, a hammer and a feather, the difference between the hammer and feather is insignificant and not easily measurable.

    NOTE 2: I just realised that if you drop the hammer and the feather at the same time, they probably (ie I'm too lazy to prove it) fall at the same rate because they're both pulling on the moon (ie acting as a single body), but if you drop them separatly, there will be a slight difference.

  • While it's nice to have this sort of evidence of planets around other stars, it's hard to actually really believe it without seeing real pictures of the planet itself.

    It's somehow quite depressing that we're extremely unlikely to visit these other solar systems within our lifetime, or even the next few centuries. It's hard to get your head around the idea that even at the fastest speed possible, it may take millennia to get there.

    I'd quite like to see the day when (if) we have colonies in other systems, or even other planets in this solar system. It's frustrating seeing it so far in the future.

    I should probably stop dreaming and read/watch some more SF. :-)
  • I see your point, the distance between two objects vanishes at a rate that does depend on the mass of both.

    I should have stated that the reaction of a body to a fixed gravitational field does not depend on the mass of the body.
  • Actually, the article stated that it's located "near the center of our galaxy". That puts it somewhere around 20,000 light years from Earth (taking our distance from the center as being around 25,000, though it does get jiggered around as new observations are made).

    Since the fastest space probe we can build now would take around 60-80,000 years to reach the nearest star system, Alpha Centauri, we can infer that the quickest we could reach this newly discovered planet is around 1,200,000,000 years. By then our own sun will likely be cooling and expanding, making Earth uninhabitable. Better hurry!

    Even if we assume the capability to speed up a craft near light speed, say a solar sail or a reaction drive using interstellar hydrogen as fuel, we're still looking at twice the length of written human history to reach this star.

    Now, assuming a warp drive, all bets are off. But that's a bit much to assume.

    As for your last question, about how Earth-like it may be, we'll probably never know. That determination would require detailed spectral analysis, and the amount of light received in these observations just couldn't have been sufficient. Whether it has an atmosphere, water, a reasonable distance from its sun ... although, given the proximity to the center of the galaxy, background radiation may well be too high for life as we know it to survive.
  • by rde (17364) on Monday September 13, 1999 @10:41PM (#1683821)
    After a report [newscientist.com] in this week's new scientist about rocky planets being formed by gamma ray bursts, I was a wee bit worried. If this is such a planet, there's no need to divide the Drake Equation [irelands-web.ie] by a thousand.
  • nfgaida wrote:
    >> We could be the fluke of the universe
    >How likely is that? out of the 300 billion stars or so, (give or take a few billion) that our planet would be the only one?

    We don't know how likely it is. It could be as common as grass; or we may be unique. We have no information either way to make a sound judgement.

    >Come on... i'm not blaming you for this view, cause many people have it.. our society has it.
    >It goes back to my point about religious arrogance.

    Well, it is a matter of faith. I happen to agree with you, though maybe not for the same reasons. I simply believe that the evolutionary process is effective enough that once life begins on a planet, reaching intelligent life is almost a given. Now, Earth had a couple of shots; the dinosaurs were around for millions of years, but they never built a space shuttle. We've only been around a few hundred thousand years, and have accomplished a great deal in a flicker of time.

    I think that is a great argument for the near-inevitability of intelligent life. On the other hand, as Larry Niven points out, there's no guarantee that we'll be intelligent at the same time as another planet's intelligent inhabitants. And that we both develop space programs, or at the very least, effective SETI. We could be a single star system away from a planet that was inhabited by intelligent life ... millenia ago.

    Again, though, the bottom line is that we have no data, so an intelligent determination is impossible. All we have are assumptions, and guesses, and extrapolations.

    Until we found out that Jupiter, Uranus, and Neptune all have their own faint ring systems, we believed that Saturn was unique. Numerous sf stories were written where our solar system was "famous" as the one with the planet with the beautiful rings. Now, we have to assume that they're everyday things. But this, of course, is what makes astronomy exciting. We like not knowing, because that means there's more stuff to find out.
  • Probably runs PlanIX
    But watch it for a while... if it turns blue and stops spinning, then we'll know the truth.
  • by zvesda (91186) on Monday September 13, 1999 @11:25PM (#1683826) Homepage
    Having been lucky enough to do a literature review on this topic recently (as part of my 3rd year u/g course) I can clear up a couple of issues;

    The method used works as follows; when gravitational field of the planet warps the space around it, any light from the star that might otherwise have 'missed' the telescope/eye/pinhole camera (!) would be 'bent' back to the aforementioned instrument.

    Hence we do _not_ see the planet, rather the effect of the planet on a star which is how all extrasolar planet detection methods (except one which has failed to date) work.

    We have no instruments capable of resolving a planet, but NASA & ESA both havbe projects that in 2020-2060 will be able to do so at IR frequencies. Hence the BBC picture is wrong. All it pointed out was the star.

    This method is not repeatable, since it relies on a chance that a background star acts as the source and the planet in orbit around an unseen star all line up for us.

    You might think, 'doesn't the planet star lens the background one?' - it does! The additional blip caused by the planet on the light curve is what gives it away.

    The typical distance to the background star (usually in the galactic plane) is 100 parsecs, the planet's parent star is usually half this distance for geometric reasons.

    Hence it's really far away! We can tell virtually nothing about the planet apart from it's mass (which won't help diffrentiate between tiny gas giants and big terrestrial types).

    If anyone want's more info (or even <gasp> a copy of my lit review, written for an intelligent person) then email [mailto] me. Dosvidania tovarish!

  • Hard to say. I didn't read the artical, so I don't know how far away it is, but since the nearest star is 8 (10? lets call it 8) light years away. If we assume that the universe ends (and mirror starts) at say 25 light years, we already know that the russions did not have a space station up 25 years ago. If the curve is farther away, you might be able to obserbe dinasors in their nateral habitat. If only our telescopes are that powerful - I understand that in theory they cannot be that powerful.

  • While I'll agree it's a stretch, you could make a case that SETI is searching for life on other worlds. Therefore, searching for those worlds does, in effect, share some of the same traits.

    You are on obvious case in point that most humans cannot think and talk at the same time

  • No no no, light has no mass. Therefor Newtonian fysics predicts that light should tot be affected by a mass. Relativistic physics does predict that radiation is affected ("It's easy once you understand that space-time is curved" - DeeDee, in Dexter's nightmare). This fact was used as once of the first observations that supported Einstein's theory: during an eclips, stars that were near the sun, could be observed to be slightly out of place, indicating that the mass of the sun had curved the path of the light between earth and those stars a little.
  • This is the first _Earth-sized_ planet discovered. Not the first planet. Other Jupiter-sized planets have already been discovered, IIRC.
  • People aren't being naive.. it's called arrogance. Specificly religious arrogance. The major religions have always tried to teach:
    1) We are created like god(ess) therefor humans are unique 2) The universe revolves around us. We are the reason for the universe existing. 3) more that i can't think of...

    At any rate, it is no suprise to me that the majority of people think of our planet as the only one to support life in the universe. and that WE are the definition of life. We meaning lifetypes here on earth. Carbon based and all that. Even science has been limited by religion, limiting our search for ETs and space exploration in general.

    I always thought when i was a kid that there were millions of planets. of course most of what i read as a child was Sci-Fi, but when i started taking science classes and reading actual science litature, i relized how far we had to go yet.

    nate

  • Not necessarily true. The reason they stated in the New Scientist article for dividing by a thousand is that only one in a thousand stars is close enough to a gamma burst to form rocky planets.

    It seems likely that the star they discovered the planet of is relatively close by (in astronomical terms, that is). Therefore, if we were close enough, that other star was probably also close enough to the same gamma burst. (Or how much do stars drift in the 4.5 billion year span we're talking about, anyway?)

    I want Drake's Equation to give a high answer as much as the next geek, but still...
  • Would someone please tell me how this post of mine is flamebait? I responded factually to an incorrect statement.

    I don't understand moderation sometimes...

    --
    Ian Peters
  • When our parents were born (assuming your's are as old as mine) the thought of reaching space at all in our lifetimes was a faery tale. When my grandparents were born, it was doubtful that this new fangled automobile thing would ever really catch on. We should not doubt the power of science. Especially when funded properly *cough*

    DWRM
  • Like some old proverbe went, every long journey begins with just one step. (or sth like that) Discovering gigantic planets was first achieved hardly a decade ago and now we've found a small rocky planet like ours. Soon we may be able see them clearly enough to analyse its atmosphere through the light it reflects to see if it would be fit for life... One things lead to another in the world of science
  • by Anonymous Colin (69389) on Monday September 13, 1999 @11:36PM (#1683845)
    Well, uh, no.

    The rest mass of a photon (particle of electro-magnetic radiation, which includes all frequencies of visible light) is 0 - not 0."some very small amount" but just plain 0. And, in the absence of electro-magnetic fields, a photon has speed c in all relativistic frames of reference. (hence "c" is the "speed of light", which is "invariant in a vacuum").

    The simplest way to think of what is actually happening is to think of space itself being "bent" by gravity and so the path of light through that space is not straight in the classical, Euclidean/Cartesian sense.

    Another way to describe what is happening, without having to understand what is meant by space being "bent" (after all, any N-dimensional manifold can be embedded in a 2*N [-1?] - dimensional Euclidean space) is that light travels along a path in space-time with minimum seperation, where seperation is a 4-dimensional measure, somewhat akin to distance, determined by the metric tensor of the space-time traversed. In the presence of a gravitational field caused by mass (actually any gravitational field - but thats an even weirder subject), the metric tensor differs from that of Euclidean 4-space, so the path of a photon is NOT a Euclidean straight line.

    (Of course, the simplest approach is just to say that gravity bends light and not try to explain why ;-)
  • Yeah, but we'll have to wait until Nasa get their Planet Finder program fully underway before we start seeing more 'tangible' information on the planets themselves. And what with the grim budget cuts congress have just dumped on them, the project might never happen.

    *sigh*

    Politicians. Don't you just love 'em?

    Dan
    --
  • Part of the problem I see with this while thing (and with astronomy in general) is that, depending on how far away this star is (and the article never said), we're seeing this 'earth-sized' planet probably *millions* of years ago. What was Earth like millions of years ago? Even thousands of years ago? A lot can happen in the amount of time light takes to travel from a distant star to earth - species come and go, cultures rise and fall... For all we know some aliens might have already blown the place up for an interstellar highway!
  • > We could be the fluke of the universe



    How likely is that? out of the 300 billion stars or so, (give or take a few billion) that our planet would be the only one? Come on... i'm not blaming you for this view, cause many people have it.. our society has it. It goes back to my point about religious arrogance.



    face it people, we aren't the best, the smartest, etc. we are *nothing* compared to the universe. this is why people like the arrogance view better.. it suits their self esteem more.

  • by dentin (2175) on Monday September 13, 1999 @11:39PM (#1683849) Homepage
    Actually, I think your estimate is a little low. I've been fiddling with some of these questions for a while now, and even have a sort of simulator that generates star systems. It looks (as near as I can tell) that about one in 10 star systems has a planet with liquid water, reasonable gravity, and appropriate temperature range.

    Also, current thinking is that the odds of life happening on such a planet is fairly high... on the order of 10 to 50% (from various abiogenesis experiments). Of course we only have one real data point, but the evidence seems to point to the idea that life isnt that hard to make.

    The probability of intelligence is significantly lower, but once they have intelligence the probability of rf technology is effectively 1, so that term vanishes as well. I don't think intelligence is that rare, and that after 5 billion years of evolution, I would put this factor around .5. You are free to use your own value of course, but given that semi-intelligent creatures abound on this rock, I don't think intelligent creatures who can use tools are that far off.

    Probability of emission frequency if fairly low as well, however not quite as low as you would think: There are certain bands that are the best for transmitting in. Most of the spectrum is filled with broadband noise, and there are a few marker frequencies that would be the most efficient/effective to transmit on. Instead of 1e-6, I'd be a bit more conservative and put it at 1e-4.

    Of course there is one more term you forgot to mention: the length of time an alien race might transmit such a signal. This is pretty much anyone's guess, but id place it at no more than 500 years - which is a really short period of time. This factor should be divided by the average age of the stars we will be looking at, which would be about 5 billion years. This factor alone works out to 1e-7.

    So the net result is .1(star with planet)*.1(planet with life)*.5(tool/rf using life)*1e-4(proper frequency band)*1e-7(prob we will catch them transmitting)

    This works out to about 5e-14 per star, which is still pretty low, but not 1e-24. Also, we can get rid of the 1e-4 factor by improving our detection technology. Additionally, the 1e-7 number may be significantly larger if electromagnetics end up being the only way to communicate across large distances. I wouldn't expect much EM radiation from the planet though, as eventually everything would go to cable/fiber optics instead of radiated waves.

    So while the odds are still highly against us, they arent quite as bad as you depict and we can increase them over time.

    -dentin
  • "If you had extensive physics (any freshman college course for example) you would know that heavy objects do in fact fall
    faster in a vacuum."

    Sorry, the gravitational force is greater on a massier object, but this increase in force balances the increase in mass precisely, so the acceleration of an object due to gravity is independent of its mass.

    Assuming m1 is the object exerting gravity, and m2 is the object affected, the acceleration a2 for m2 is

    a2 = F/m2 = (G*m1*m2/d*d)/m2 = G*m1/d*d

    That is, acceleration, and hence velocity, is independent of the size of the mass accelerated.

  • The other star was at the center of our galaxy. That's a long ways away. Furthermore, it's unlikely to have moved from the arm to the center in 4.5 billion years.
  • I still think that's rather unlikely.

    For a start, you can't just accelerate to near light speed in an instant. If you want to survive the experience you'll have to keep to an acceleration of a few g. I haven't done the sums (any takers? I'd be quite interested to know the answer) but I wouldn't be surprised if that rather limited the distance you could get to even taking into account the time dilation effects.

    Secondly, just think of the amount of energy you'd need to generate for that sort of acceleration (and probably slowing down at the end too, if there's no-one there already to catch you).
  • Sure, simulations can give an answer to what the expected number of and size distribution of planets is for a planetary system, but we don't know this is true until we observe enough planetary systems to tell if our models are any good. I've certainly heard of models that give distributions close to what we observe in our own system.
  • what is wrong with just calling it That New Planet... at least until we find another one...
    then we can just call it That Tiny Planet...
  • The Drake equation depends in one key portion on the number of earth-size planets out there.
    The more accurate a count, the better we can figure out the probabilities.

    SETI would receive far more funding, for example, if we had evidence of pure oxygen (although it's possible that that isn't necessary) in the atmosphere of planets orbiting 50% of all stars.

    O2 has a hard time existing on it's own, being so reactive and all...

    But still, even if we knew earth-size planets were common, SETI would be a much higher priority.
  • A lot of people are debating the whole 'of course there are planes out there, we can't be the only one' arguement. But look at it statistically - If we assume that the universe can be represented by a bell curve (no, I'm not going to get into new-fangled 'natural' statistical curves here), then the solar system could, probability-wise, fall anywhere inside that curve (from our starting sample size of 1, we have no reference where to place ourselves).

    So we start looking at the universe. We find a lot of stars, but none with obvious planets. Instead of consigning the Solar System to one of the tail ends of the bell curve, we assume we don't have equipment sensitive enough to detect planets yet (which we didn't.)

    So we design better equipment. We start finding some (a few) Gas giants orbiting stars. And we go, "Ah-hah! See, we're not alone! We must fall somewhere within the center of the normal curve!" Yet still the sample size is small compared to the number of stars - which would really shove 'stars with Gas Giants' to outside one or two standard deviations, and 'stars with earth-sized planets' even further out, with a single sample we know of.

    Now we find a (possible) star with another earth-type planet (Class M? Class L? When are scientists going to look up the Star Trek regs and tell us what Class Mars is?), and we say, "We are definately not unique." But look at the statistics - even with *2* systems with earth-sized planets, your sample is *miniscule* compared to the billions of stars! We could very well be in the extreme tail of the bell curve, and actually *be* unique in the universe!

    Until SETI produces results, or an alien shows up on Prime Time TV during the President's State of the Union address, I don't think anyone will be able to say for sure that we are not alone. I, for one, believe that we cannot be - I cannot concieve of such a lonely universe. But we really don't have any proof to the contrary. yet. So, while this is very important, don't loose perpective on what it really means about our place in the universe.
  • It kinda depends what you mean by Earth-like really... It's very very likely that there's no sprawling civlization with Ion cannons and there's unlikely to be even any real life. Really all this tells us is that there is a planet which is a bit like ours(& mars) and by the assumption that what we actually see is not very much at all, you can kinda deduce that there's plenty more planets like Earth & mars & we should keep looking

    And also planets don't change an awful lot in a coupla million years. The species may be completely different and the continents may not be the same, but the potential for it to support life would remain pretty much unchanged.
  • Uhhh.... no.

    Acceleration due to gravity has nothing at all to do with the mass of the falling object, only with the mass of the attractor.
    Read up on your physics. [mines.edu]

    (for your curiosity: G = 6.6725985 x 10^-11 Nm^2/kg^2 )

  • Only if all the kernel authors would get together and re-release Linux under the GPL (Generic Planet License). Maybe if the planet has a few moons, it would make a neat Beowulf...


    ---------------------
    the SlashDot spellchecker:
  • "Why the hell do you want to colonise everything? Isn't it a better idea to stop polluting our own planet? Stop wasting its resources so rapidly?"

    With that attitude we'd all still be on one continent. Not that I don't agree that pollution and resource depletion are serious problems.

    One good and time tested way to stop using resources here is to get them somewhere else. It doesn't look like anyone else is too interested in the asteroids at the moment, perhaps we can be permitted to use some of them? Maybe even start some space colonies to support that activity?

    It's likely going to be a long time before we're capable of even near interstellar voyages, let alone colonization missions. Perhaps we'll even have better ethics about destructive exploitation by then.
  • by J05H (5625) on Tuesday September 14, 1999 @12:01AM (#1683866) Homepage
    Just the first one found around a main sequence or nearly-main sequence star.
    In 1989, three Earth sized (well, one is Mars sized, but close enough) planets were discovered
    orbitting a pulsar. They are obviously dead planets, like their star, but they always fail
    to be mentioned, especially in the mainstream media. Anyway, check out the Extrasolar Planets Encyclopedia [obspm.fr] for more info on all of this.
  • We're a life form. Colonization of available habitats is what life forms do. All life forms (or else they go extinct). Biological imperative.

    Our adaptability and technology just makes more habitats available to us.
  • &gt We could be the fluke of the universe.How likely is that? out of the 300 billion stars or so, (give or take a few billion) that our planet would be the only one? Come on... i'm not blaming you for this view, cause many people have it.. our society has it. It goes back to my point about religious arrogance. It has nothing to do with arrogance; it's scientific rigor. It's not unreasonable to expect rocky planets to exist in other solar systems, but a scientist cannot just ass/u/me it. Making assumptions about the universe, based on a sample size of one solar system -- now that would be arrogance. Making guesses and then confirming them with observations is science.
    ---
    Have a Sloppy day!
  • To kinda state the obvious, all of our assumptions are based on what "we", as humans know. A good example is just several hundred years ago, all mankind knew the Earth was flat and the Sun revolved around it. We now know this to be totally inaccurate. Are we so arrogate as to assume that our limited scientific knowledge is the be all, end all in astophysics? Just because life on Earth is Carbon based, this doesn't mean that life elsewhere is. It is the unweilding, unable to change nature in biological entities that cause their extinction.

    That's my rant. Tht's better than kicking the dog.

    I feel better know.

  • Of course light has (photons have) mass. Just not rest mass. Mass and energy are equivalent, right? (E=mc^2). Light has energy, right? (hv, where h=Planck's constant, v=greek letter nu, frequency).

    Therefor light has mass.

    (At rest, though (well, photons don't rest, but..) the frequency goes to zero, thus so does the mass.)
  • The pulsar planet system you refer to was also the first example of extra-solar planets of any kind, not to mention the first multiple system. There are rumors of other pulsar planets but I am not aware of other published evidence.
  • Statistics-schmatistics.

    I actually find the 'arrogance' view that we are unique and alone in the universe to be a lot more humbling and saddening that the view that there's teeming masses of life out there just waiting to be 'discovered.'

    Personally, I find it more likely that there is life out there, but less likely that we'll ever know about it. Brings me down to think about it.
  • Yep. All made good sense.

    I saw a program a little while ago (I think it might have been on the Open University, I'm not sure), where they stated that it should be possible (albeit with space bourne spectrometers, far more sensitive than the ones we have up there at the moment), to work out the compisition of the atmosphere of said planets, by differencing the spectra of the light of the parent star against the spectra of the light shining through the atmosphere of the intervening planet.

    Dan
    --
  • 'People' believed that they were told by those they considered authoritative, ie the church. Chances are if you wandered up to an 18th century peasant and asked what shape the Earth was, you'd get a blank look or be locked up as a loony.
    Scientists -- people who made predictions based on the available data -- would come to various conclusions, not all of which were 'the earth is flat'.
    Having said that, your point is valid; the reason a lot of people have problems with such subjects as Relativity is that they've no experience of time dilation; it therefore seems counter-intuitive.
  • My understanding is that time dilation means the
    travel time experienced by the traveller goes to
    zero as velocity approaches the speed of light.

    The distance between us & the remote planet is
    compressed *for the traveller*, approaching zero
    as the travellers velocity approaches c.
  • What? And would you prefer that they added false color to make it pretty for you? That would take about 30 seconds. The point is Pluto & Charon's surfaces are very very very hard to see and this is showing us some detail. I think it's actually a good thing that they aren't doing the false-color-so-it-looks-pretty-for-the-yokels-at-h ome thing. . . Astronomers do that too much. . .
  • Of course, the problem with this method is that it's a lot easier to find a massive planet close to a star than a tiny one. Guess what kind of planets we've found by this method: large ones close to stars. The observations to date are horribly skewed by the only reliable method.
  • I assume that the gravity lensing difference between the two stars can easily be picked out because although they both throw a lot of light, they don't have the same spectrum, and probably not even the same redshift. You can then subtract out the closer star because you very carefully observed it when there was nothing significant behind it.

    This is not gravitational lensing, but gravitational microlensing. From the BBC text I guess it's the planet's gravitational field modifying the star's light curve. The light curve is a plot of light intensity vs time. For a main sequence star, i.e., a "regular" one, say, Sol, there's no reason for the light curve to change over a small period of time (400 days or less, typical in microlensing events). Now, what puzzles me is an Earth sized planet's gravitational field isn't strong enough for the effect to be measurable.

    You can look here [mira.org] and here [u-strasbg.fr] if you are interested in more information about gravitational lenses. I couldn't find more details at Mount Stromlo Observatory's homepage [anu.edu.au].

  • Actually, there is some evidence (albeit sort of round-about) that all life everywhere must be either Carbon or Silicon based with a strong preference towards carbon. Now, this could just be a case of us believing that because there is ample evidence on Earth for that hypothosis, but there is some evidence (and my argument is really weak right now because I can't find the book) that in order to develop bone structure, etc. the extraterrestrials would have to be carbon or silicon based. Damnit. . . I'll post it if I can find the book. . .

    Another little interesting tidbit is the theory that all intelligent civilizations see eclipses. . . that's an even weirder argument about the tides and all that. . .

    Just a few ramblings of my mind. . .
  • The rest mass of a photon (particle of electro-magnetic radiation, which includes all frequencies of visible light) is 0 - not 0."some very small amount" but just plain 0. And, in the absence of electro-magnetic fields, a photon has speed c in all relativistic frames of reference. (hence "c" is the "speed of light", which is "invariant in a vacuum").

    You've given the two important points, but failed to connect them in a useful way. The rest mass of a photon is exactly zero, but we never observe photons at rest. They always travel (through a vacuum) at c. Each photon has a energy proportional to its frequency. Dividing the energy by c^2 gives the mass of a moving photon which is a function of it's frequency.
  • There is also the issue of how common are planets.
    I would guess that people always assumed that *SOMEWHERE* there were other planets. But they seem to be a common thing. That is exciting.
  • Unfortunately for all the little planet discussed in this story will reveal itself to be the true home of Steve Jobs. Hence, a Macintosh planet or oMac (for orbiting Mac).
  • wait a sec...shouldn't it be called iPlanet? Or is that name already taken? ;-)
    --------------------------
  • That has got to be the silliest thing that i have ever heard argued in my entire life. It's so akin to:

    "Gosh, i can't see past the horizon.. so the earth must end there."

    That it makes me want to laugh.

    There are NINE planets in out solar system. Somewhere around 5000 stars visible to the naked eye (and literally countless others that we use sensitive instruments to detect). I'm simply stating the obvious fact that there has to be at least some planets orbiting some of those stars out there.
    --
  • by Anonymous Coward
    Maybe it's not gravity lensing, maybe it's gravity mirroring and we're looking at ourselves! The universe is curved.
  • ...is that the statistical probability of the planets we found has life is way too low, as well as the probability of that life being intelligent, and the probability that It has found how to generate RF signals of a reasonable strength...
    p(find rf)= p(life) X p(intelligence) X p(rf technology) X p(emmission frequency)
    probably like ~1x10^-6 for each term, which gives us like p(find rf) ~ 1x10^24 for each rock. Not good odds if you ask me.
  • From the article, it's clear that the planet hasn't actually been seen, just inferred from
    examinination of the "light-curve" of a star seen better through the gravitational lens affect.

    Fun stuff.

    I was dissapointed, though, that the article missed any mention of just how far away this new
    planet is, and perhaps how far it would take to reach it using conventional space travel. Or
    better still, how likely it is to be Earth-like in ways that might make it colonisable if we were
    ever able to reach it...

    Then again, perhaps I should knock off reading sci-fi for a few days :)
  • i mean p(find rf) ~ 1x10^-24.....sorry 8)
  • While the gamma-ray hypothosis is interesting, it needs alot of further investigation before we should start to divide the Drake Equation by 1000. There's an awful lot we still don't know about planetary formation and this is just one explanation so we shouldn't jump to conclusions.

    Given the extraordinary pictures the Hubble Space Telescope has porduced of stella formation and protoplanetary discs, I for one would love to see a next generation Space telescope with an order of magnitutde greater power put into orbit which might give us some more data to explain the planetary foramtion process.

    Of course with the GOP trying to kill NASA's science research budget there's not much chance of this happening.
  • >by definition there are no intra-faith conflicts

    That's because those that go against their own faith are labeled as heretics, etc. How the faith deals with them can be at times very Not Nice (TM)

    >Humans are by nature a very brutal species-- religions are important institutions which can ameliorate this brutishness

    true. humans are brutal. however, education is far better at making people play nice than forcing them to because their "god" told them too. Education lets them see that there are better ways to do things (they choose their path), whereas religion forces you along it's "chosen" path.

    Plus, (and this applies mainly to the catholic religion) many religions make one of their founding points "humans are evil, you are evil" not a good thing for self esteem..

  • If you want to solve something with statistics, solve something that's determinable.

    Tackling your problem, start with the known facts, and a bit of logic:

    * Every physical object in the universe is composed of atoms, and an atom of hydrogen here on earth is just like an atom of hydrogen in any star in the universe.

    * The very act of being a star brings about changes whereby the star is eventually reduced to heavier elements, mostly iron.

    * Solar systems are created when enough matter condenses to form a star and satellites.

    With these facts established, we extrapolate that the the life-cycle of solar systems are similar. They form, are comprised of the same elements, and fade toward the same end.

    The two major variables are the balance (proportions) of the elements, and temperature.

    Are we unique in the universe? Absolutely. But only in the sense that life evolves. The life on this planet today is unique with respect to any other day. Different people, difference plants, different animals, different species, etc...

    When the elements blend with the right balance and a suitable temperature, there will be life.


  • Just to play devil's advocate here, but why couldn't this Solar System be the anomaly? Granted, on a bell curve we have a statistical likelihood to be in the middle, but that does not rule out the possibility that we might be at one of the extremes - even one percent of 300,000,000,000 stars (your number) is still a lot of stars.
  • not to mention the name. how can we even talk of a planet if we don't know its name?
  • Of course, that's assuming that the planet's creation, life, whatever, are happening on the same timeline as Earth's. However, us humans have been playing around with technology and stuff for only about 6000 years. Not a lot of time in a discipline that can be off by a billion or more. seeing as stars are of all different ages, some planets out there could have a billion years or more of evolution over us, which lends itself (hopefully) to some fantastic discoveries on their part.
  • Hmm, the 5-second explanation on CNN last night showed an animation where the detection involved the eclipsing of the star by the planet. So if this is right, they didn't detect the light reflecting off the planet, they detected the obscuring of the star as the planet orbits.
  • by technos (73414) on Tuesday September 14, 1999 @12:37AM (#1683916) Homepage Journal
    Finding planets this way is a really haphazard way of doing it. Stars rarely line up well enough to make gravitational lensing really viable as a method of detecting another planet. Another method they've been using is watching the Doppler shift of a selected star. Any star with an object revolving around it exibits a regular 'wobble' in the shift. Make a guess at the mass of the star, apply some centuries old math to it, and voila! You know how many objects are orbiting the star, how massive they are and how far away from the star!.
  • Permit me to clear up a few questions and misconceptions. Interested readers can read the technical details for themselves in preprints on the LANL server:

    A good summary:
    http://xxx.lanl.gov/abs/astro-ph/990819

    The event MACHO-97-BLG-41
    http://xxx.lanl.gov/abs/astro-ph/9908038

    The event MACHO-98-BLG-35 (to which this Slashdot article refers indirectly)
    http://xxx.lanl.gov/abs/astro-ph/9812252


    Okay, now for my comments:

    1. Contrary to "cemerson"'s post (which should have been moderated to "MisInformative" :-), the work _was_ done in with optical telescopes; in fact, small ones, only a meter or so in diameter (rather than the 8-meter or 10-meter behemoths like Keck). The basic method is to take pictures of the same field of stars over and over and over, and look for variations in the brightness of any star with time. The technique works best if one can point at a large number of stars at once; the two best sources for crowded fields are the Bulge of the Milky Way and our nearest neighboring galaxy, the Large Magellanic Cloud. Both are best viewed from the southern hemisphere, and the data described in the recent press releases comes from Chile, South Africa, and New Zealand.

    2. The Bulge of the Milky Way is about 8,000 parsecs (about 25,000 light years) away from us. The LMC is about 50,000 parsecs away. These are the "background" stars. A star roughly halfway between us and the "background" will cause the greatest lensing effect as it passes between us and the "background" star.

    3. When such an event occurs, the "background" star becomes brighter. Now, here's the key: if the "foreground" object is a lone star, then one can predict theoretically the shape of light curve: the background star brightens slowly at first, reaches a somewhat sharp peak in brightness, and then fades exactly as it brightened: the rising and falling phases look exactly the same, symmetric. And, in fact, most of the observed microlensing events (there have been over 100 followed in the past decade) follow this predicted, symmetric curve very closely.

    4. But, if the "foreground" object is not a lone star, but a binary star, or a star with a planet, the light curve will depart from its theoretical, symmetric shape. If there's a planet around the foreground star, and it passes in front of the background star, it can cause a distinctive "spike" in the light curve: a short, sudden, very brief rise and fall. The event MACHO-98-BLG-35 shows a LITTLE bit of evidence for such a spike: see Figure 9 in the paper by Yock:
    http://xxx.lanl.gov/abs/astro-ph/9908198

    5. There are several efforts underway to detect planets around other stars by searching for the tiny 'eclipses' caused as a planet passes in front of its star in its orbit, but no solid detections yet. This is very difficult, because even a big planet like Jupiter causes only a (roughly) one-percent dip in the light of its star -- and many stars vary by more than one percent. Planets like the earth decrease the light by even smaller amounts, maybe one-hundredth of one percent. At that level, _most_ stars are variable. So, one must disentangle the intrinsic variation of the star from the brief dip caused by the planet -- and that means waiting months/years for the planet to come around in its orbit again. You can find information on one such search, Kepler, at this site:
    http://web99.arc.nasa.gov/~mars/vulcan/

  • and an even better question, is anyone pointing radio telescopes at these flying rocks?

    If you look at the picture at the top of the BBC article, you'll see that it isn't from an optical telescope. I would bet that they _did_ use radio telescopes rather than X-ray, IR, etc., particularly as the observatories are on Earth (Australia and New Zealand) rather than in orbit.
  • by AleT (51575) on Monday September 13, 1999 @10:53PM (#1683933)
    It's not silly. It's a perfectly valid point.

    Astronomy is a science where you can not repeat
    your experiment (the universe). Whenever you
    get a result, in this case the result is that
    we live on a planet, you have to spend a long
    time considering any possible biases. The fact
    that we'd be dead if we weren't on a planet is
    a pretty big bias towards finding ourselves on
    one, even if it's the only planet in the universe.

    As for it being pretty obvious that there are
    other planets out there, 1000 years ago it was
    pretty obvious that the earth was flat.

    Ale.
  • Lensing occurs with any mass of object. The size
    of the effect depends on the mass of the lens, and
    on its position. Lensing has been observed around
    the sun, which is not very massive.

    In this case, they were looking for the
    distinctive brightening of the light from a star
    which would occur if some object like a dead star
    or jupiter sized planet passed exactly infront
    of a background star. From studying the number
    of such events, you can calculate the amount of
    mass in our galaxy made up of such `dark' objects.

    What they found is that one of their light curves
    didn't match the theoretical curve. Unfortunately
    the experiment is essentially not repeatable, as
    you'd have to wait for something else to pass
    in front of that star, which could be thousands of years.

    Ale.
  • This would be a huge dissapointment! ...but if you think about some of it, it does make good sense. I'm only an amateur astronomer/physicist (if you can even call me that) and I've always wondered how the rocky planets came together.

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