Re: Degrees or Arc minutes to Km's

From: Tony Beresford (
Date: Mon Jun 30 2003 - 00:09:45 EDT

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    At 07:58 30/06/03, you wrote:
    >Greetings all,
    >I know this is off topic but I didn't know what other group to pose this
    >question...What is the equivalent of Arc minutes to Km's  or Degrees to
    >Km's.  I just observed The Noss 2-3 triplet going through Ursa Major with my
    >binos and started to think if all three can fit in my field of view and my
    >field of view is 1.8 degrees in diameter and at the end of the pass the
    >leader and follower were just at the maximum of my field of view.  How many
    >Km's apart would they be if I could translate degrees into Km's?  I measured
    >angular separation between two of them (leader and follower) and came up
    >with around 1d and 41m.
    If you state angles in radians, rather than degrees, then 
    size = distance * angle  
    this formula makes use of the approximation that for small angles measured
    in radians  sin(x) = tan(x) =x. It is a customised version of the
    trignometric formula  size = distance *tan(angle).
    Radians are an angular measurement used in mathematics. The are two times pi
    of them in  a circle, so to convert degrees to radians you divide by 57.295 ( 180 /pi)
    there are of course 3437.7 min of arc in a radian, so to convert minutes of arc
    to radians, divide by 3437.7. 
    >That reminds me of a question someone asked me awhile back which was, which
    >state in the United States would fit nicely into the bowl of the big dipper?
    >The big dipper being 10d by 5d, it didn't appear to be that big for a state
    >to fit inside of it or am I wrong...I didn't know...anyone out there care to
    >take a stab?
    I think this is to do with shape rather than size.
    Tony Beresford
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