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The Internet Technology Science

Global Internet Telescope Tops Hubble's Resolution 221

Posted by timothy from the peer-to-peer-peering dept.
satorchi writes " The Arecibo Observatory together with the European VLBI Network have used the internet to make a real-time transatlantic synthesis telescope. Data from the individual telescopes was transfered via the internet, and processed in real time by the central processing station at the Joint Institute for VLBI in Europe. 9 terabits were transfered during the 20 hour experiment, and the resulting synthesised telescope had a resolution of 20 milliarcseconds, about 5 times better than the Hubble Space Telescope (HST). This level of detail is equivalent to picking out a small building on the surface of the Moon!"
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Global Internet Telescope Tops Hubble's Resolution More

Global Internet Telescope Tops Hubble's Resolution

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  • Does this mean (Score:5, Interesting)

    by The_Mr_Flibble ( 738358 ) on Tuesday October 05, 2004 @07:33AM (#10437920)
    we can look for the place where the moon landings took place to finaly debunk all those sceptics ?
    • Then they'll claim the whole Internet Telescope is a global spoof.

    • Re:Does this mean (Score:5, Insightful)

      by ahillen ( 45680 ) on Tuesday October 05, 2004 @07:36AM (#10437935)
      I don't know, but if you see something, the sceptics will claim the picture is fake.
      • But in the other hand, IF YOU SEE NOTHING?!
        What will the government say, if the landing WAS fake and we manage to prove it?

        Yes, yes, there's enough proofs that it was real. Except all of them could've been fabricated... :P

        There's one more extra option: The landing was real. The video was fake :P

    • Re:Does this mean (Score:5, Insightful)

      by prodangle ( 552537 ) <mathesonNO@SPAMgmail.com> on Tuesday October 05, 2004 @07:39AM (#10437954) Homepage Journal
      Sadly I doubt it. If they weren't convinced by the reflectors, nothing will convince them http://www.lpi.usra.edu/expmoon/Apollo11/A11_Exper iments_LRRR.html http://nssdc.gsfc.nasa.gov/database/MasterCatalog? sc=1969-059C&ex=4
      • You believe that?

        It doesn't strike you that it would be simpler to point the laser at a satellite which, after a suitable delay, returns a similar pulse?

        But, let's give the "scientists" the benefit of the doubt, and assume they really are bouncing lasers off the moon. (Those of you with even high-end laser pointer experience will find that hard to accept, but bear with me.)

        The article *you* linked to states that unmanned Soviet missions left reflectors on the moon. Isn't it easier to accept that the Amer
        • The conspiracy theorist are as bad as some of the extreme religious groups and the OS zealots (be they Ms or *nix). No mater how much information you give the tin foil hat crowd to the contrary of what they believe they will never change their mind. In this case I doubt that even sending them directly to the moon to show them a lander would change their mind. So at some point you must just stop trying and just pity them. Such a sad life they must live. The fact of the matter is that more or less anything i
    • It amazes me that so many allegedly "educated" people have fallen so quickly and so hard for a fraudulent fabrication of such laughable proportions. The very idea that a gigantic ball of rock happens to orbit our planet, showing itself in neat, four-week cycles -- with the same side facing us all the time -- is ludicrous. Furthermore, it is an insult to common sense and a damnable affront to intellectual honesty and integrity. That people actually believe it is evidence that the liberals have wrested the la
      • This was the funniest yet most insightful post I've seen in a long, long while. People who have their beliefs won't yield them no matter what we do to convince them. We could increase science funding so people can hopefully learn how to process information, but I doubt it. There's a huge crunch, at least in New York, on science teachers.

        We should stop modding the guy "Funny" and "Informative" instead, since the former doesn't increase his karma. In fact, he should post a dumb comment and then mods should g
        • We should stop modding the guy "Funny" and "Informative" instead, since the former doesn't increase his karma. In fact, he should post a dumb comment and then mods should go and mod that up just to equalize his karma.


          Well, the fact that politics is mentioned in his post means he automatically gets 40% flamebait / overratted / offtopic / troll, 40% informative / insightful / underrated, and 20% funny.
        • Too bad it's a repeat [slashdot.org] of a repeat [slashdot.org] of a repeat [slashdot.org] of a repeat [slashdot.org]
        • We should stop modding the guy "Funny" and "Informative" instead, since the former doesn't increase his karma. In fact, he should post a dumb comment and then mods should go and mod that up just to equalize his karma.

          Or, maybe he should just quote his source [darrenmart.com].

          Of course, that fact that he's called TrollBridge shouldn't tip you off at all...
        • The only way to prove space travel to some people is to take them into space. Unfortunately none of those crackpots can afford the ticket and they'd probably say they were on some kind of motion simulator the whole time. (I'd sure like to see a simulator that can simulate free fall...)
      • There is a very famous "moon" picure at this one web site that has goat in it's name...
      • Mmmmboy, I'd bet you'll be doubly amazed if I pointed out the gigantic ball of plasma in the sky. Actually, it's not the sun, it's the universes largest heat bulb. The liberals had to scrape all of the fillament out of the moon in order to creat it.

    • Re:Does this mean (Score:3, Interesting)

      by Traa ( 158207 ) *
      we can look for the place where the moon landings took place to finaly debunk all those sceptics ?

      If the comment was sincere then tell me how exactly you would want to convince someone who doesn't listened to reason. Hopefully you see the contradiction.

      Here is my view of the universe:

      The Real Universe
      - what really happens. What really is/was/shall be
      - population 0

      The Physical Universe (feel free to call it something else like 'personal universe')
      - The rules we come up with that describe as best we can

  • 9 TB / 20 hours (Score:4, Interesting)

    by mirko ( 198274 ) on Tuesday October 05, 2004 @07:36AM (#10437937) Journal
    How heavily has this impacted the transatlantic Internet communications, during these 20 hours ?

  • Costs (Score:4, Interesting)

    by tcdk ( 173945 ) on Tuesday October 05, 2004 @07:37AM (#10437939) Homepage Journal
    Does anybody have an idea about the cost of such a telescope (if you where to build a new one) compared to the Hubble?

    Maybe a space based replacement for Hubble isn't needed...

    • Re:Costs (Score:3, Interesting)

      by Lord Prox ( 521892 )
      Maybe a space based replacement for Hubble isn't needed...

      You are forgeting the first rule of govt spending. Spend big. What we need is a space based version of this "limited technology demo"

    • Re:Costs (Score:5, Informative)

      by LiquidCoooled ( 634315 ) on Tuesday October 05, 2004 @07:45AM (#10437988) Homepage Journal
      This method of merging data from multiple telescopes is equivilent to tiling together all the images from all the spectators at an event.

      You get more information because of a larger number of eyes.

      This principle has been known about for years and years, it just seems that the software/hardware to synchronise this and pull it off is coming into standard use.

      From the article:

      Until now, VLBI has been severely hampered because the data had to be recorded onto tape and then shipped to a central processing facility for analysis. Consequently, radio astronomers were unable to judge the success of their endeavours until weeks or months after the observations were made. The solution, to link the telescopes electronically in real-time, now enables them to analyse the data as it arrives. This technique, naturally called e-VLBI, is now possible as high-bandwidth network connectivity has become a reality.

      • Re:Costs (Score:4, Informative)

        by drinkypoo ( 153816 ) <drink@hyperlogos.org> on Tuesday October 05, 2004 @10:44AM (#10439311) Homepage Journal
        It's superior to tiling. The content of the images is used to build a single composite image that eliminates much of the distortion received by any individual telescope because each telescope's distortion will be different. Every telescope can thus examine the same target, and produce a "picture" superior to what any one of them can produce.

        • Re:Costs (Score:2, Informative)

          by LiquidCoooled ( 634315 )
          Absolutely, and if I remember rightly, this is a similar technique that the "see throught the smoke" cameras use.

          Each individual lens may glimpse details the others cannot, and when brought together, the sum is greater than the parts.

          Building up the best image possible based upon multiple viewpoints.

          The analogy I gave initially is correct, except we cannot walk all around the arena, but instead have many eyes from a very narrow viewpoint.

    • This is not a replacement for Hubble (Score:5, Interesting)

      by Animaether ( 411575 ) on Tuesday October 05, 2004 @07:49AM (#10438003) Journal
      The title of this story is stupendously moot. It's like saying "oil tanker carries more weight than freight train". Yes, I'm sure it does. It also doesn't go across land.

      Very similarly, this is an antenna (radio astronomy) not a telescope (optical astronomy).

      Even if it were a telescope, it would still be limited by atmospheric distortions (hence why you'd want one in space).

      And even if it were a telescope in space, you'd probably end up with WEBB - which lacks sensors in many of the ranges that Hubble does cover.

      All of the above lead up to at least two results...
      1. Less scientific data

      and, arguably more important as it drives the public's opinion/enthusiasm/taxpaying-willingness/etc.

      2. Far less pretty pictures.

      I suggest doing a search for Hubble on Slashdot and reading the +5 Insightful/Informative posts, as many of them go into detail as to why many of the proposals simply aren't a replacement for Hubble, and why it either should stay up - or a proper replacement be built.

      • about interferometric telescopes... (Score:5, Informative)

        by mforbes ( 575538 ) on Tuesday October 05, 2004 @08:23AM (#10438170)
        Interferometric telescopes can drastically increase the resolution as compared to single-tube telescopes.

        Having two scopes one mile apart, as far as resolution is concerned, is equivalent to having a single one-mile-wide mirror (in essence; the previous poster is correct in his argument about atmospheric distortions & other problems).

        The problem is that the amount of light collected is still based solely on the sum of the surface areas of the mirrors-- not the effective area.

        If not enough light (or radio waves, in this case) is collected to trigger the CCDs, the object throwing out the radiation simply won't be detected.

        Incidentally, the Keck telescopes in Hawaii work this same way, but with a much shorter baseline. It helps that, at two miles above sea level, they're above much of the atmosphere, and that they both have fairly large mirrors to begin with.

        For more information about how they work, Google lists plenty of resources.
        • It's also very important to note than the signals being combined in interferometry must be aligned to within a half a wavelength of tolerence (IIRC). So, for a radio signal, this is pretty easy. For optical interferometry, however, this is incredibly difficult and requires remarkably precise tuning of the optical path. This would be why optical interferometry is done on relatively small scales (although there are a number of projects out there working to build larger optical interferometers).
      • Plus, I wonder what that small building on the Moon looks like in the radio spectrum, for it to be a meaningful object when comparing resolutions...

        Maybe if the building has wi-fi or electrical wiring of some kind?
      • It will be interesting to see how well this telescope will work on long-time integration imaging.

        That's another area where Hubble excels because it can integrate an area of sky for several orbits (Hubble Deep Field, for example), picking out very faint galaxies from nearly individual photons. These ground-based scopes, while integrating for long times, will probably integrate more scattered atmospheric light, and not be able to extract faint galactic signals from atmospheric noise nearly as well as Hubbl

    • Re:Costs (Score:3, Informative)

      by photonic ( 584757 )
      Apparently you can build the largest (100 meter) steerable radio telescope [nrao.edu] for 75M$ [aip.org]. Arecibo is not steerable and is build in a valley, so it will probably cost less than that. Add in a few dozen smaller dishes all over the world [evlbi.org], probably costing less than 30M$ each for a small one. Add some bandwith costs, supercomputers and other fancy equipment. Grand total for all hardware worldwide won't be much more than 1B dollar, or about 1 or 2 shuttle launches without the cost of a hubble.

      However, that does not

  • Bender Says (Score:5, Funny)

    by lukesky ( 211936 ) on Tuesday October 05, 2004 @07:38AM (#10437948) Homepage
    Oh, no room for Bender, huh? Fine! I'll go build my own lunar lander, with blackjack and hookers. In fact, forget the lunar lander and the blackjack. Ahh, screw the whole thing!

  • I demand proper units of measurement (Score:4, Funny)

    by Max Romantschuk ( 132276 ) <max@romantschuk.fi> on Tuesday October 05, 2004 @07:41AM (#10437963) Homepage
    9 terabits were transfered...

    Yes, but how many Libraries of Congress is 9 terabits equivalent to?

  • And the first building spotted on the moon? (Score:3, Funny)

    by Anonymous Coward on Tuesday October 05, 2004 @07:42AM (#10437968)
    The monolith factory.

    bkd
  • The GIT?
    git
    n : a person who is deemed to be despicable or contemptible; "only a rotter would do that"; "kill the rat"; "throw the bum out"; "you cowardly little pukes!"; "the British call a contemptible person a `git'" [syn: rotter, dirty dog, rat, skunk, stinker, stinkpot, bum, puke, crumb, lowlife, scum bag, so-and-so]

  • d/l speed (Score:3, Informative)

    by tod_miller ( 792541 ) on Tuesday October 05, 2004 @07:50AM (#10438010) Journal
    9TB = 9895604649984 bytes

    20 hours = 72000 seconds

    =

    137438953.472 bytes/second

    =

    134217.728 Kb / Sec

    =

    ~ 131mb / sec

    =

    0wned!

  • TMA (Score:5, Funny)

    by TeknoHog ( 164938 ) on Tuesday October 05, 2004 @07:51AM (#10438013) Homepage Journal
    ..picking out a small building on the surface of the Moon!

    Such as the 1:4:9 monolith?

  • Actually, the resolution is not comparable (Score:5, Informative)

    by Anonymous Coward on Tuesday October 05, 2004 @07:52AM (#10438023)
    The comparison between Hubble's and Arecibo's resolution is misleading. The hubble telescoope operates in the viewable spectrum of light, while Arecibo and VLBI do radio astronomy. Radio waves are several magnitues longer, so it's even more difficult to get the same resolution. But since the frequencies are lower, too, it is possible to synchronize several telescopes using interferometry.

    Interferometry [wikipedia.org] is done at ESA's VLT with up to four telescopes and mirrors with a precision of about 10nm in the viewable spectrum, at a distance of about 100m. But here, we have a distance of several thousand kilometers, so the signals are digitalized and put together at the computer. This is difficult because it's really hard to synchronise the time -atom clocks are not precise enough. Hence the synchronisation is done "so that it fits best", not using any precise clock. (I don't think this is any easier to do, kudos to the scientists at arecibo and VLBI!)

  • No Way! (Score:3, Funny)

    by N8F8 ( 4562 ) on Tuesday October 05, 2004 @07:53AM (#10438027)
    picking out a small building on the surface of the Moon

    Silly wabbit, everyone knows the secret buildings on the moon are either underground or otherwise camouflaged!

  • Amazing fact-oid: "...the signal from the distant star was more than a billion billion times weaker than a typical mobile phone handset!"

    If a typical mobile phone handset was really the equivalent of a billion billion supernovas, then you could see why they don't let you use them on aircraft. Even one supernova stuck in your ear might cause cancer over long periods. Okay, I know the comparison is really between the signal from the supernova and the signal of a mobile phone somewhere within its operating ra

    • > If a typical mobile phone handset was really the equivalent of a billion billion supernovas, then you could see why they don't let you use them on aircraft. Even one supernova stuck in your ear might cause cancer over long periods.

      Well, as you pointed out, it's about signal strength. You'll die of old age before you get enough space shuttle main fuel tanks of energy from either source to cause cancer.

  • So it can transfer 9TB in 20 Hours but can't take slashdot for just 5 minutes!!

  • Apples and Oranges (Score:5, Informative)

    by cobyrne ( 118270 ) on Tuesday October 05, 2004 @07:55AM (#10438037) Homepage

    Comparing a synthesised radio telescope (as was done here) with the Hubble is like comparing apples and oranges. It is MUCH harder to generate these kind of high-resolution pictures in visible as it is in radio.

    For instance, if I were to use the VLBI technique in optical wavelengths, and if I had conditions where atmospheric turbulence wasn't affecting the image (as happens with radio), I would produce 20 milli arcsecond resolution with telescopes less than 10 metres apart, as opposed to telescopes on different continents!

  • Ground telescopes surpassed Hubble years ago (Score:4, Informative)

    by Anonymous Coward on Tuesday October 05, 2004 @07:57AM (#10438051)
    Ground-based telescopes using adaptive optics surpassed Hubble years ago in terms of resolution. Prior to adaptive optics, atmospheric turbulance dictated a ground-based telescope's resolution (how close two objects can be and still be distinguished as "separate objects"). The advent of adaptive optics and telescope interferometry as largely solved the problem with the atmosphere so that resolution continues to increase with mirror size or in the case of multiple telescopes in an interferometer setup, the size of the baseline.

    Ground-based telescopes have a number of clear advantages in addition to high resolution: they're easily upgraded/repaired and they cost far less than a Shuttle launch.

    That said, space-based telescopes still have some advantages over their larger ground-based counterparts: first, they're obviously not subject to day and night but the big advantage is that a space telescope can observe in wavelengths that would be blocked by the Earth's atmosphere.

    They're complimentary technologies.
    • They're complimentary technologies.

      I just had a vision of arriving in a hotel room to find it occupied by a several metre wide cylinder that fills the entire length of the room; I squeeze around it to the phone and call reception. "Oh, that's the complimentary space telescope. We haven't launched it yet."

      I think you mean complementary.
    • Wut ? The use of AO is still largely confined to the longer wavelengths and over tiny, tiny fields of view compared to that of the whole instrument.

      The absence of decent, bright, guide stars often limits performance, and the synthetic, laser induced, stars have their own problems.

      And space based scopes can see when its cloudy on Earth.....

      Steve
    • While the second part of this statement has some truth, the first part of this statement is completely false. Adaptive Optics on ground-based optical telescopes are just barely starting to get in the same ballpark as HST, when it comes to resolution. You have diffraction-limited imaging on HST, which gives you a resolution of 0.05 arcseconds (see here [hubblesite.org]). I have NEVER heard of anyone getting better than 0.3 arcseconds from the ground (and rarely even anything approaching that). Moreover, optical interferometr
      • I have NEVER heard of anyone getting better than 0.3 arcseconds from the ground (and rarely even anything approaching that)

        Well, that's not true. Speckle interferometry [wolfram.com] can get to 70 milliarcseconds at 1.2 microns wavelength, and I'm working on an AO system that can get down to 85 milliarcseconds. What you may mean is that the Strehl ratio is nowhere near as good, which is very true.

        If you are talking about the visible bands though, then it is true that hardly anyone has done well in that wavelength reg

        • Yes. You're absolutely right. Speckle can give you much better resolution. But for most astronomy, Speckle isn't an option, and most AO systems can't do much better than 0.3 arcseconds. But now you've got me interested. What AO system are you working on that can get down to 85 mas? I would think that, even if you can do that, it would still be over a relatively small field of view, because of the size of the isoplanatic patches in the atmosphere. . . unless you're doing different corrections at different p

          • Well, the 85 mas is for the MMT AO [mmtao.org] deformable secondary mirror system. I've reduced Ks band images with 90 mas full width at half maximum, and that's pretty repeatable. We're not the best by any means, and I've seen better images from the larger telescopes, but that's mostly due to larger aperture and having excellent seeing. (Nobody will showcase images from AO nights of 2 arcsecond seeing!)

            The general definition of resolution is pretty fuzzy anyway (no pun intended) for AO systems, because the FWHM does

      • Yep, in the visible wavelength, I agree with you. The best seeing I've seen myself is 0.34", it didn't last long, though... However, it should be noted that DIMMs have seen better than 0.3", the Maidanak DIMM, had down below 0.2" (and below 0.3" 2% of the time), see this paper [u-strasbg.fr].

        Also note that Roque de los Muchachos Observatory at La Palma (where I've been observing) has even better conditions, but the weather at the Roque can get really bad. I've had my share of that too... Too bad Maidanak is a country th

  • Slashdotted already!!! (Score:2, Informative)

    by sat1308 ( 784251 )
    Coral Cache [nyud.net]
    Note - Doesn't seem to be working. Use mirrordot in case of that.

    Mirrordot [mirrordot.org]

    Karma whoring since 1962!!!

  • Hubble reference site (Score:3, Informative)

    by erick99 ( 743982 ) <homerun@gmail.com> on Tuesday October 05, 2004 @08:02AM (#10438070)
    The Hubble Space Telescope Project [nasa.gov]. This is an excellent guide to the 'scope and instrumentation on board the Hubble.

  • Clarification (Score:4, Informative)

    by hak hak ( 640274 ) on Tuesday October 05, 2004 @08:02AM (#10438073)
    For clarification, this is not about an optical telescope, so (as another poster pointed out) this kind of telescopes will not be a replacement for the Hubble. Interferometry of this kind is (with current technology, but even in principle) only conceivable with radio astronomy, not with optical astronomy.

    The principle involved is the same principle which has been used for some decades now in radio interferometry: the data (consisting of the electric field as a function of time) from several radio telescopes are recorded (with timestamps) and then sent to a correlator which combines the signals. This means that in contrary to optical interferometry, the interference is not realised in real time, but `simulated' afterwards in a computer.

    The difference is in the way the signals are transported; they used to record the data on magnetic tape drives, which are still used but are more and more being replaced with hard disks. Apparently they have now also started to use the Internet to transport the data.

    • Re:Clarification (Score:2, Informative)

      by BigBlackDog ( 692924 )
      I beg to differ: http://www.mrao.cam.ac.uk/telescopes/coast/ [cam.ac.uk]

      Not only is optical interferometry possible in principle, it is possible with todays technology.

    • Re:Clarification (Score:2, Informative)

      by mforbes ( 575538 )

      Interferometry of this kind is (with current technology, but even in principle) only conceivable with radio astronomy, not with optical astronomy.

      Perhaps I'm reading this wrong-- or misinterpreting what you mean by "this kind". The WM Keck [hawaii.edu] telescopes in Hawaii-- visible light scopes-- already use interferometry.

      The principle is exactly as you describe, with timestamped data being combined on a separate processor.

      Interestingly, other arrays (planned or already existing) that are designed to search for

  • Not Optical (Score:5, Informative)

    by TonyJohn ( 69266 ) on Tuesday October 05, 2004 @08:09AM (#10438102) Homepage
    Very simply, this aperture synthesis experiment is not the same as being able to resolve a house on the moon, unless the house was emitting radio waves. Optical aperture synthesis is harder, but it has been done, at COAST [cam.ac.uk], among others.
    • To implement aperature synthesis you need to have the phase of the signal. Almost all optical recording devices just record the amplitude or intensity, because light waves vibrate at teraherz, i.e. beyond present day electronics, although we are closing in. Radio operates a megaherz which is easy to capture, record, transmit the phased signal.

      If you have a full signal and high fidelity transimssion system you can send the actual light signals, with phase, to an analog inferometric synthesizer. This is
  • > 9 terabits were transfered during the 20 hour experiment

    Seems like they exhausted all paid bandwidth with it.

    - Hey John, we're running out of bandwidth this month.
    - Well, Mike, we have about 2 gbytes left, it's enough for us.
    - WTF?!? 1 gbytes
    - 0 gbytes
    NO CARRIER

  • An integrating idea. (Score:3, Interesting)

    by Anonymous Coward on Tuesday October 05, 2004 @08:17AM (#10438132)
    Suppose that you wanted to detect a very faint object. You could aim your telescope at a given point in the sky for a couple of hours each night. You could integrate the image over a six month period. That should give you a baseline of 186 million miles never mind a paltry couple of thousand miles.

    One of my favorite experiments is to take a sine wave buried under about 20 dB of noise. By integrating over a long enough period, the signal emerges beautifully. (of course it has zero bandwidth) The neat thing about this is that your detector only has to resolve one bit; you still get a nice sine wave out. This should work for detecting dim stars and I'd be suprised if they didn't do it. Do they? Any astronomers out there?
    • "Do they?"

      Yes.

    • Suppose that you wanted to detect a very faint object. You could aim your telescope at a given point in the sky for a couple of hours each night. You could integrate the image over a six month period. That should give you a baseline of 186 million miles never mind a paltry couple of thousand miles.

      The catch is that you have to know both your position to sub-wavelength precision and the current time to within a fraction of a wavelength period in order to make measurements over that time and distance range.

  • true geekery (Score:3, Insightful)

    by blooba ( 792259 ) on Tuesday October 05, 2004 @08:46AM (#10438274)
    we computer guys think we're geeky, but these stargazers make us look like a bunch of high school jocks.

  • This level of detail is equivalent to picking out a small building on the surface of the Moon!

    OK, let's see:

    levelOfDetail = distanceEarthMoon / sizeBuildingOnMoon

    whereas

    distanceEarthMoon = 384.400.000 m
    sizeBuildingOnMoon = 0 m
    DIVISION BY ZERO

    Stupid comparison...

  • Resolution Math (Score:5, Informative)

    by sat1308 ( 784251 ) on Tuesday October 05, 2004 @09:13AM (#10438432)
    Here's some math to explain what a resolution of 20 milliarcseconds really means.

    1 arcsecond = 1/3600 degrees
    Therefore, 20 milliarcseconds = 20/3600000 degrees = (20/3600000)/360*2pi radians

    Delta = arctan(diameter/distance)
    where Delta stands for angular diameter. This formula is the basic definition of angular diameter. (Note : This formula automatically implies that the units of angular diameter are same as the unit of a plane angle, i.e. radian/degree)

    Taking tan function on both sides we get
    tan Delta = diameter/distance

    Since resolution of the telescope is (20/3600000)/360*2pi radians we get
    tan ((20/3600000)/360*2pi) = diameter/distance.

    Now,
    tan ((20/3600000)/360*2pi) = 9.69627362*10^-8,

    This means that
    9.69627362*10^-8 = minimum diameter/distance
    which can be restated as
    distance*9.69627362*10^-8 = minimum diameter

    By substituting distance as required, we can obtain the diameter of the smallest observable object at that particular distance.

    For example, taking (mean) earth-moon distance as 385,000 km we get
    minimum diameter for an object on the moon to be observable = (385,000*9.69627362*10^-8) km = 0.0373306534 km = 37.3306534 m (approx.)

    All math was done using Google's calculator and all formulae/definitions are from Wikipedia.

    Disclaimer : I may have misinterpreted/misued the formulae so the above results are open to mistakes.

    Mod this up anyway, I'm sure somebody will find my mistakes, if there are any (I hope not :)), that is.
  • The top post completely missed the point of the press release.

    VLBI has been getting this kind of angular resolution for decades, this is not news. The news is that they've combined the signals from telescopes positioned across the globe in *real time*, which is a first.
  • At some point, maybe thousands of years from now, maybe tomorrow, the star is expected to blow itself apart in one of the most energetic phenomena known in the Universe - a 'supernova'. [...] With the incredible power of e-VLBI, radio astronomers are now poised to catch the details as they happen [...]

    I'd hate to be the poor sod who's staring into the eyepiece when this thing blows. AHHHHHH, MY EYESSS!!!! I'M BLINDED!!!!!

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