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Math is like love -- a simple idea but it can get complicated. -- R. Drabek
Math is like love -- a simple idea but it can get complicated. -- R. Drabek
Re:Moderation alert (Score:1)
Re:Common sense (Score:3)
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.
BBC appears to have muddled the facts (Score:2)
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
Re:The only problem with looking for RF signals... (Score:1)
Re:That's a relief (Score:1)
So what gives?
/.
Re:Common sense (Score:1)
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"
Re:Not the first Earth-sized planets, either (Score:1)
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.
Re:Common sense (Score:1)
Re:Distant planets (Score:1)
"The number of suckers born each minute doubles every 18 months."
Re:But how far? (Score:1)
And, of course, for the slapstick comedic value.
"The number of suckers born each minute doubles every 18 months."
Ummmm... (Score:1)
Let's call it 4.3 ly
Re:But how far? (Score:1)
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.
Re:seeing is believing (Score:1)
Re:Common sense (Score:1)
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.
Couple of clarifications (Score:4)
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.
I don't claim to be an expert on such issues, but hopefully someone got something from my little rant here.
Colonisable? WTF? (Score:1)
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.
Re:Common sense (Score:2)
pffffff.
Re:Lensing (Score:1)
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...
Re:Lensing (Score:1)
>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.
easy to test that one (Score:1)
jsm
Re:Common senses - heavy objects fall faster (Score:1)
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)
Re:Couple of clarifications (Score:1)
It's a big, big, big universe. I'll give it that.
"The number of suckers born each minute doubles every 18 months."
Re:Clear up a few points (Score:1)
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.
not suprised that there are planets (Score:1)
now what we need... (Score:2)
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?
Suprised? (Score:1)
Common sense (Score:1)
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.
--
Re:Couple of clarifications (Score:1)
Re:Common sense (Score:1)
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."
Re:Common sense (Score:1)
Finding them is just like finding more evidence for evolution - it's obvious - but it's nice to be reminded how right we are
Re:Anyone ? (Score:1)
therefore is runs BeOS
Close, but not cigar (Score:2)
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.
Distant planets (Score:1)
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.
Re:Close, but not cigar (Score:1)
I should have stated that the reaction of a body to a fixed gravitational field does not depend on the mass of the body.
Re:But how far? (Score:2)
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
That's a relief (Score:3)
Re:Couple of clarifications (Score:2)
>> 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
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.
Re:Anyone ? (Score:1)
But watch it for a while... if it turns blue and stops spinning, then we'll know the truth.
Clear up a few points (Score:5)
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!
Re:Hey wait a minute!! (Score:1)
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.
Re:SETI (Score:1)
You are on obvious case in point that most humans cannot think and talk at the same time
Light has no mass (Score:1)
Not the first (Score:2)
Re:Common sense (Score:2)
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
Re:That's a relief (Score:1)
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...
Re:Common sense (Score:1)
I don't understand moderation sometimes...
--
Ian Peters
Reaching them in our lifetimes (Score:2)
DWRM
Re:Common sense (Score:2)
Re:Lensing (Score:3)
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
Re:Distant planets (Score:1)
*sigh*
Politicians. Don't you just love 'em?
Dan
--
Earth-like? But how much? (Score:2)
Re:Couple of clarifications (Score:1)
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.
Re:The only problem with looking for RF signals... (Score:3)
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
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
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
Re:Common senses - heavy objects fall faster (Score:2)
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.
Re:That's a relief (Score:1)
Re:Not necessarily... (Score:1)
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).
Re:freak occurance (Score:1)
Re:now what we need... (Score:1)
then we can just call it That Tiny Planet...
Agreed (Score:1)
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.
Are we alone? (Score:2)
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.
Re:Earth-like? But how much? (Score:1)
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.
Re:Common senses - heavy objects fall faster (Score:1)
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 )
Re:Anyone ? (Score:1)
---------------------
the SlashDot spellchecker:
Re:Colonisable? WTF? (Score:2)
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.
Not the first Earth-sized planets, either (Score:3)
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.
Re:Colonisable? WTF? (Score:1)
Our adaptability and technology just makes more habitats available to us.
Re:Couple of clarifications (Score:1)
---
Have a Sloppy day!
Re:Couple of clarifications (Score:1)
That's my rant. Tht's better than kicking the dog.
I feel better know.
Re:Lensing (Score:1)
Therefor light has mass.
(At rest, though (well, photons don't rest, but..) the frequency goes to zero, thus so does the mass.)
Re:Not the first Earth-sized planets, either (Score:1)
Re:Couple of clarifications (Score:1)
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.
Re:Couple of clarifications (Score:1)
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
--
Re:Common sense (Score:1)
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.
Re:But how far? (Score:1)
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.
Re:POV-Ray PLuto (Score:1)
Re:freak occurance (Score:1)
Re:Couple of clarifications (Score:1)
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].
Re:Couple of clarifications (Score:1)
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. . .
Re:Lensing (Score:2)
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.
Re:Common sense (Score:1)
I would guess that people always assumed that *SOMEWHERE* there were other planets. But they seem to be a common thing. That is exciting.
Re:Anyone ? (Score:1)
Re:Anyone ? (Score:1)
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Re:Common sense (Score:1)
"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.
--
Hey wait a minute!! (Score:2)
The only problem with looking for RF signals.... (Score:2)
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.
But how far? (Score:1)
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
Re:The only problem with looking for RF signals... (Score:2)
Re:That's a relief (Score:1)
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.
Re:Common sense (Score:1)
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..
Re:Are we alone? (Score:1)
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.
Re:Couple of clarifications (Score:1)
Re:now what we need... (Score:1)
Re:Earth-like? But how much? (Score:1)
Re:Lensing (Score:2)
freak occurance (Score:3)
More information on microlensing (Score:2)
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"
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/
Re:now what we need... (Score:2)
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.
Re:Common sense (Score:3)
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.
Re:Lensing (Score:2)
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.
Re:That's a relief (Score:2)