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A Telescope as Big as the Earth

Posted by ScuttleMonkey on 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.'"

6 of 172 comments (clear)

  1. FYI by Gabrill · · Score: 4, Informative

    This technique is being used.

    --
    Always going forward, 'cause we can't find reverse.
    1. Re:FYI by Bemopolis · · Score: 4, Informative

      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, a much smaller version of the same technique.

      --
      "I guess the moral of the story is, don't paint your airship with rocket fuel." -- Addison Bain
    2. Re:FYI by Nyeerrmm · · Score: 4, Informative

      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.

  2. Re:Were they looking in the optical range? by Robotbeat · · Score: 4, Informative

    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.

  3. Re:Cool by Gloy · · Score: 5, Informative

    You haven't tried Google Sky, then?

  4. Re:OK by evanbd · · Score: 5, Informative

    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.