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Homework Help: What is a arc-second?

  1. Apr 24, 2007 #1
    I looked it up in several areas on the web but nothing really helped, there is no definition in my physics book. anyway, I had a question about the hubble telescope and I found its resolution to be about 0.1 arc-seconds . Thats great and all but what does that mean really? for example, how small an item is the hubble able to see with that resolution?
  2. jcsd
  3. Apr 24, 2007 #2


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    One degree of angle is divided into 60 minutes, each minute is divided into 60 seconds. So the number given is a very small angle. But this number is actually the resolving power. Hubble can see stars that have angular disk sizes much smaller than this. But it can only see two of them as distinct objects if they are separated by a larger angle than this.
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