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Space Science

A Telescope as Big as the Earth 172

Posted by ScuttleMonkey
from the now-come-the-arguments-on-where-to-point-it-next dept.
Roland Piquepaille writes "A week ago, seven telescopes around the world were linked together to watch a distant galaxy called 3C273 in real time and create a single world telescope. The data from these telescopes, which are located in Australia, China and Europe, was streamed around the world at a rate of 256 Mb per second. One of the Australian researchers involved in the project said that it was the first time that astronomers have been able to instantaneously connect telescopes half a world apart. He added that 'the diameter of the Earth is 12,750 km and the two most widely separated telescopes in our experiment were 12,304 km apart.'"
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A Telescope as Big as the Earth

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  • by Anonymous Coward on Friday September 07, 2007 @02:11PM (#20511521)
    ...all data from the Shanghai telescope was filtered and replaced with promotional material for the Peoples Republic of China. Apparently the galaxy bears a striking resemblance to Chairman Mao.
    • Re: (Score:3, Funny)

      by Anonymous Coward
      ... all data from the Shanghai telescope was found to be contaminated with high levels of lead, antifreeze, and banned food additives.
      • Re: (Score:3, Funny)

        by Anonymous Coward
        ...all data from the Shanghai telescope was found to be manufactured by child laborer using Google Sky. The children are paid in World of Warcraft Gold which a small division of the group help to mine from the game.
        • Re: (Score:3, Funny)

          by Anonymous Coward
          ... all data from the Shanghai telescope was found to be a cleverly reverse-engineered copy of American and European data. Officials at the World Intellectual Property Organization could not be reached for comment.
  • FYI (Score:5, Informative)

    by Gabrill (556503) on Friday September 07, 2007 @02:13PM (#20511553)
    This technique [wikipedia.org] is being used.
    • Re:FYI (Score:5, Funny)

      by moderatorrater (1095745) on Friday September 07, 2007 @02:28PM (#20511831)
      I read up on it, but I didn't see the downsides of this technique being discussed. What's the drawback of using this technique as opposed to an actual earth-sized telescope?
      • Re:FYI (Score:5, Informative)

        by Bemopolis (698691) on Friday September 07, 2007 @02:55PM (#20512241)
        Total amount of signal gathered. That is to say, you gather less rain with a few buckets scattered across a field ratherthan a field-sized bucket. On the plus side, since you are monitoring simultaneously at different sites, you can compare the signals among the antennae to get the same spatial resolution of a telescope the size of the Earth. Compare to the VLA [wikipedia.org], a much smaller version of the same technique.
        • by tygt (792974)
          ie, you don't get as much light.....
        • Or the VLBA [wikipedia.org], a 'world-sized' very long baseline interferometer. At the VLBA, they record the data from each of the ten antennae to tapes with very accurate timestamps, then combine the data later at the NRAO facility in Socorro, New Mexico.
          • by Shag (3737)

            Or the VLBA [wikipedia.org], a 'world-sized' very long baseline interferometer.
            Yeah... although I wouldn't really call it "world-sized" since the maximum baseline is only 5000 miles or so. :)

            (I work up the hill from the westernmost VLBA dish.)
          • by RogerWilco (99615)
            The big difference with how the VLBA operates and how the EVN (european VLBI network) operates, is that this was done in real time, so called e-VLBI. No tapes, no harddisk packs, but live lightpaths across the globe.

            See http://www.jive.nl/ [www.jive.nl] for all the details and http://www.astron.nl/dailyimage/main.php?date=2007 0906 [astron.nl] for some images.
      • Re: (Score:3, Funny)

        by Waffle Iron (339739)

        What's the drawback of using this technique as opposed to an actual earth-sized telescope?

        One advantage of the actual earth-sized telescope is that if you tweak the electronics a bit, then the instrument can also be used as a weapon to destroy rebellious planets.

      • Re:FYI (Score:5, Informative)

        by Nyeerrmm (940927) on Friday September 07, 2007 @03:53PM (#20513087)
        There are two reasons to make a really big telescope (whether optical, radio, or even x-ray). FIrst you pick up more photons, allowing you to pick up dimmer, more distant objects and get less noisy data. The second is that you get improved angular resolution, since the limiting factor for resolution on a good telescope is the diffraction of light, a consequence of the wave nature. Simply, the angular resolution is approximated very well by Rayleigh's Formula:

        Resolution(radians) = Wavelength/Diameter

        When you do this kind of technique, you increase the angular resolution that can be picked up to that of a full telescope over the area (if designed properly to get the middle resolutions as well). However, as others have mentioned, you don't get the full number of photons, which means you have to increase the imaging time or allow for much high SNRs. However, this is still very useful for getting high resolution images of fairly bright objects.
      • Re:FYI (Score:4, Informative)

        by schwanerhill (135840) on Friday September 07, 2007 @04:29PM (#20513621)
        In addition to the lower light-gathering power, interferometers need to sample a wide range of separations between pairs of antennae. The most-separated pair of antennae (the longest baseline is the jargon) gets very small structures, but is not sensitive to larger structures. You get helped by the rotation of the Earth, which makes any given pair of antennae (which are fixed on the Earth) change their angular separation with respect to the target the array is looking at, but that only helps so much. You really need a range of separations, which means many antennae.

        For example, the Very Large Array has 27 antennae. That's 351 pairs, which can be spaced differently. If you had a single dish telescope the size of the VLA (or the Earth), you'd get every angular scale at once, without having to synthesize a large aperture from all the baselines.

        In practice, this aperture synthesis [wikipedia.org] technique works quite well, and there's no way we're going to build a steerable single dish telescope larger than the Green Bank Telescope [wikipedia.org] (100m in diameter) any time in the foreseeable future.
  • by Liquidrage (640463) on Friday September 07, 2007 @02:13PM (#20511555)
    Wow! And I thought SCT's had a large central obstruction.

    Ok. That might be the geekiest joke in the histroy of /.
    :(
  • I have seen radio telescopes linked in such a way to form a "larger" antenna. Is this similar?
    • by Robotbeat (461248) on Friday September 07, 2007 @02:23PM (#20511739) Journal
      This is in the radio range, not the optical range. The summary misled me to thinking it was in the optical range, which would be an impressive achievement, indeed! The news of this story is that it was done in real-time, over a network connection, instead of by shipping data from each radio telescope site on hard-drives to a location be processed later.
      • I had the same reaction. Bummer... But honestly, it is good that astronomers are catching up to something which for particle physicists, is business as usual.
      • This is in the radio range, not the optical range.

        Damn. This means all we got for this was reruns of the Aploterix! and Andy show from Betelgeuse.

      • by Nyeerrmm (940927) on Friday September 07, 2007 @03:38PM (#20512829)
        Just to expand on this comment for other readers, any time you do this with any kind of wavelength, you have to have the positions of the telescopes known within fractions of a wavelength. Radio waves range from meters to millimeters, so precision on a worldwide scale is difficult but not impossible at this range , although doing it in real-time is still an impressive feat, as this used to be done by recording the signals to tape, taking them to a central location and processing the data then.

        However, expanding it to optical frequencies (where you can pick up different types of objects and also do so to much higher resolution) is difficult, since the wavelengths are around 500 nanometers, a level of precision that is still impossible on worldwide scales, except maybe in space, where you can depend on laser range finding over very long distances, although i don't know of any proposals trying to do this over very large scale.
      • You have to crosscorrelate two sources to created an effective larger aperture. (From recently deceased Stanford Professor Ronald Bracewell's textbooks.) Radiowaves vibrate between kiloHertz to gigaHertz. Current electronics is fast enough to capture, transmit, and record both amplitude and phase of radio signals. Its not fast enough for optical teraHertz yet.

        Before signal processing was fast enough they cross-correlated the analog radio signals. This is how VBLI astronomy works.
        The do this with opti
    • I have seen radio telescopes linked in such a way to form a "larger" antenna. Is this similar?

      You may be thinking of an interferometer. It's virtually the same thing. Very Large Baseline Inteferometry (VLBI)has been around a long time. The deal here is that now it can be done in real time.

  • Cool (Score:3, Interesting)

    by CaffeineAddict2001 (518485) on Friday September 07, 2007 @02:15PM (#20511589)
    It would make a great plugin for google earth. Instead of zooming in on earth from space, you could zoom into space from earth.
    • Re:Cool (Score:5, Informative)

      by Gloy (1151691) on Friday September 07, 2007 @02:24PM (#20511761)
      You haven't tried Google Sky [google.com], then?
      • No =) I should have guessed that google had already done it though.
      • by Torvaun (1040898)
        Never used it, no time to now. Is it anything like Celestia?
      • by Khyber (864651)
        Google Sky is okay, but Celestia is much more interesting, as it also tracks hubble and ISS' orbits around the earrth, as well as the moon during it's phases, and it's in 3-d.
    • by ls -la (937805)
      I actually had a program like that about 10 years ago. Universe explorer? Something along those lines. Anyway, you could put in a date and look at the sky for whenever you wanted, you could find the next solar or lunar eclipse, etc. It was cool while I was hooked on astronomy.
      • I actually had a program like that about 10 years ago. Universe explorer? Something along those lines. Anyway, you could put in a date and look at the sky for whenever you wanted, you could find the next solar or lunar eclipse, etc. It was cool while I was hooked on astronomy.

        And now there's Stellarium [stellarium.org] available for free to do this.

  • All at once (Score:5, Funny)

    by Blitz22 (1122015) on Friday September 07, 2007 @02:16PM (#20511611)
    I for one, welcome our giant eyed, galactic..... I soviet Russia, the world telescopes .... Scientist can finally peer deep into goat..... be gentle.
  • Real time? (Score:3, Insightful)

    by Odiumjunkie (926074) on Friday September 07, 2007 @02:16PM (#20511613) Journal
    > A week ago, seven telescopes around the world were linked together to watch a distant galaxy called 3C273 in real time and create a
    > single world telescope.

    Not to be overly pedantic, but the data were streamed from all over the world to a location in Europe, then processed, and then streamed to China for viewing.

    Even though they weren't going over the public net, that's still almost certainly >1000ms latency. Harldy "real time".

    Although, I suppose that's acceptable on top of the two and a half years it took for the photons to get to us.
    • Re: (Score:2, Funny)

      by FiveLights (1012605)
      There's a galaxy only two and a half light years from here? It's suddenly feeling awfully crowded...
      • Hrm.

        I just wiki'd 3C 273 [wikipedia.org] and took the distance from that, but I see now that's a quasar, not a galaxy.

        Perhaps TFA made a mistake? It seems unlikely that there would be both a galaxy and a quasar with that name.
        • Re: (Score:3, Funny)

          by caerwyn (38056)
          You missed the "G" in front of the ly for that object. 2.44 Gly is a bit further away than 2.44 ly.

          A quaser that close to the earth would be a less than pleasant galactic neighbor.
        • by ls -la (937805)

          Hrm.

          I just wiki'd 3C 273 [wikipedia.org] and took the distance from that, but I see now that's a quasar, not a igalaxy.

          Perhaps TFA made a mistake? It seems unlikely that there would be both a galaxy and a quasar with that name.

          Quasars [wikipedia.org] are at the center of galaxies. There are a few possibilities for what is actually happening; most likely the scientists are studying the quasar, mentioned it was the center of a galaxy, and the nontechnical reporter made a small mistake.

    • Re: (Score:3, Informative)

      by ls -la (937805)
      Not to be overly pedantic, but light from another galaxy takes more than 2.5 years to get here. Light from the closest (known) star [wikipedia.org] takes 4.22 years to get here. The article didn't say how far away the galaxy was, but 2.5 *billion* years would be a better guess, and that's on the low side.
    • by geekoid (135745)
      Don't be stupid. Jeez, by your definition, NOTHING is real time.
  • OK (Score:2, Insightful)

    by Anonymous Coward
    I think I would rather have one high altitude large aperture 'scope looking at an object all night rather than two at the opposite sides of the world. The ones on the opposite sides of the world won't be able to look for long before one of them disappears over the horizon. Not only that but they are looking through the maximum amount of atmosphere.

    This stunt is a technical accomplishment but maybe not that important in and of itself. What would get me excited would be a couple of orbiting 'scopes.
    • Re:OK (Score:5, Informative)

      by evanbd (210358) on Friday September 07, 2007 @02:27PM (#20511809)
      It's a radio telescope; the atmosphere is almost irrelevant. This gives a very large effective size for diffraction purposes, meaning the resulting images can be much more finely resolved.
    • Well, these are radio scopes, so the atmosphere isn't a problem. And the new "Lucky" imaging technique (Reported just a few days ago) solves a lot of the distortion problem. Now, 2 scopes at a large diameter have the same resolving power as a single scope with a diameter equal to the distance between the 2. So it really is like having a telescope the size of the earth. The only thing they don't have is light-gathering capacity, and the arrays used are large enough that that isn't really a problem.
    • by drerwk (695572)
      By having the scopes at the opposite ends of the Earth and sharing phase accurate data between them they have an aperture size equivalent to their separation. Which is larger than any single scope you could launch. You could launch two scopes and do the same thing, but the dish size you get on the ground is rather larger than what we can launch.
  • Coordinating scopes on the moon, mars, and earth - that would be quite a "light bucket", no?
    • by Tony Hoyle (11698)
      Yeah but they'd probably only come into alignment for a couple of days every few years.

    • Send a few radio telescopes in different directions in Voyager-like trajectories. Every year you'd get higher and higher resolution. All the signals would reach Earth at approximately the same time, so the interferometry would need to cope with just a 15-minute difference between the signals, even though the telescopes would be multiple light-hours apart.

      As a bonus, these telescopes would also increase, year by year, the range of the parallax technique, the most accurate technique for finding stellar dist
  • by ec_hack (247907) on Friday September 07, 2007 @02:29PM (#20511847)
    One of the Australian researchers involved in the project said that it was the first time that astronomers have been able to instantaneously connect telescopes half a world apart.

    This is the real story - FTL communications!

  • A source of hope (Score:5, Insightful)

    by athloi (1075845) on Friday September 07, 2007 @02:33PM (#20511933) Homepage Journal
    We have problems on earth, but most of them will never be solved. Poverty will always exist. Stupidity will always exist. So will criminality, alcoholism, drug addiction, and failure. We can either spend our time obsessing over the negative, or we can choose to explore space and find a new future. I'm glad that we continue to probe space, to consider sending up ships, and most all, that we keep space exploration alive in our minds as a source of hope.
    • The good news is that 94% of every human being who has ever lived is now dead.
      • Re: (Score:2, Funny)

        by jcorno (889560)

        The good news is that 94% of every human being who has ever lived is now dead.


        If it makes you feel any better, it's really closer to 50%, and most of those people were douchebags.
        • The good news is that 94% of every human being who has ever lived is now dead.
          If it makes you feel any better, it's really closer to 50%, and most of those people were douchebags.
          That's an interesting thought. The quickest answer I could find was this Google Answers answer [google.com] (a wonder, since I searched on Google!).
    • by Saeger (456549)
      True - Humans alone aren't smart enough to solve all our age-old earthly problems, but the true source of hope isn't in exploring outer space in tincans; we'd just take our problems with us. No, the true hope is in developing and merging with friendly A.I. before we destroy ourselves with increasingly powerful technology. The end of most of our problems will coincide with the intelligence to shed our scarcity-based evolutionary baggage and begin exploring innerspace.

      The Singularity is nearing.
  • One of the Australian researchers involved in the project said that it was the first time that astronomers have been able to instantaneously connect telescopes half a world apart.
    So how did they break the speed of light? Bha. In my day we respected the laws of physics.
    (get off my porch)
  • This is known as VLBI, and it's been done since the 1960's. During the mission of the Japanese VSOP [isas.ac.jp] satellite, we had telescopes bigger than the Earth.

    What is new here is the real time data transport, not the observations.
  • I wonder what the Storm botnet could do?
  • Curiousity Question (Score:2, Interesting)

    by StickyWidget (741415)
    "He added that 'the diameter of the Earth is 12,750 km and the two most widely separated telescopes in our experiment were 12,304 km apart.'"

    So, when measuring the distance between each of the telescopes, did he do it through the planet (diameter), or did he measure the distance across the surface of the planet (circumference)? Cause that kind makes a huge difference, and really screws up any valid comparison between the two distances.

    ~Sticky
    /You know, kind of like comparing English furlongs and Austr

    • Re: (Score:2, Informative)

      So, as the crow flies or as the Horta [wikipedia.org] tunnels? The summary leaves this detail out but TFA is explicit:

      The diameter of the Earth is 12 750 km and the two most widely separated telescopes in our experiment were 12 304 km apart, in a straight line," Dr Tzioumis said.
  • Apparently, they must not have seen anything good, because there are no pics in the article... I don't know why they'd run an article about some awesome new telescope -- without the most important feature of any telescope -- a picture of what it can see.
  • I have a map of the United States... Actual size. It says, "Scale: 1 mile = 1 mile." I spent last summer folding it. I also have a full-size map of the world. I hardly ever unroll it. People ask me where I live, and I say, "E6".
  • The news here is using the Internet for a real-time transmission of a substantial bandwidth of RF to a central correlation receiver. Non-real-time "whole earth telescopes" have been running since the 1970s. It's called Very Long Baseline Interferometry [wikipedia.org].
  • 3C 273 is a Quasar, not a galaxy (According to wikipedia at least). Are they talking about the galaxy containing/near the Quasar, or what?
    • Re: (Score:3, Informative)

      by Xolotl (675282)
      Follow the link to the wikipedia article on quasars.

      "Quasar" is short for "Quasi-stellar object" which is what they were called when they were first discovered. At the time, they were unresolved sources a bit like, but clearly not, stars. Since then it has been discovered that quasars are one form of active galaxy, where accretion onto the black hole in the nucleus of the galaxy releases a lot of energy. So in this sense "galaxy" is accurate. If someone wants to specifically talk about the rest of the gal

  • ...because their 52kb/s upload from Comcast just didn't cut it.
    • Re: (Score:3, Funny)

      by hansamurai (907719)
      And the fact that they would get throttled in favor of Comcast's own Earth-sized telescope.
    • by RogerWilco (99615)
      If I'm correct, it is because the VLBA still uses tapes, and most of it's telescopes aren't connected at all.
      A major part of this effort has been getting the Gbit/s quality links to the telescopes, that are often in a desert in the middle of nowhere, as you want to avoid radio-interference from human sources, so you prefer places that have no human inhabitants within 200-300 km of your location.
  • by aapold (753705) on Friday September 07, 2007 @03:32PM (#20512751) Homepage Journal
    I mean, what they observed already happened long ago. We're just observing it now, and that's fine, but theoretically they could just each independantly observe, timedcode, and then sync it all up later.

    Its not like it was a live event where you had to have it just then.
    • Re: (Score:2, Informative)

      True enough, but I seem to understand from the rest of the article that convenience is the main gain. "'We used to record data on tapes or disks at each telescope, along with time signals from atomic clocks. The tapes or disks would then be shipped to a central processing facility to be combined,' Dr Tzioumis said." So no, there's not much gain in information (that I can see) but rather it's a lot easier and faster to have all of the data sitting there, ready for you to play with. Or whatever they plan to d
  • Data rate (Score:3, Informative)

    by Anonymous Custard (587661) on Friday September 07, 2007 @03:52PM (#20513077) Homepage Journal
    "The data from these telescopes, which are located in Australia, China and Europe, was streamed around the world at a rate of 256 Mb per second"

    This means that over 10 seconds 2560Mb of data would be streamed, according to NASA.
  • All of this trouble, and all we seem to have gotten from it is a picture [csiro.au] of the Earth (telescope pointed at a giant space mirror?) and a picture [csiro.au] of one of the telescopes themselves (don't know how they got that one).
  • It sounds like synchronization is the keyword here. Who cares that the telescopes were synchronized ? As long as they follow the same object and timecode all their datas, the synchronization could have been made offline. Or am I missing something ?
  • Only I thought we were going to have to wait till they did it with telescopes in orbit. So when are they publishing the pictures after all the data is combined? Huh? When?
  • Playing around with Google Earth I note these telescopes are on nearly a straight line! With two more, one in Somalia and one in Alaska one would have the telescopes in a near perfect cross! Please Somalia and the US, join!

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