# Re: Degrees or Arc minutes to Km's

Date: Mon Jun 30 2003 - 00:09:45 EDT

• Next message: Chris Peat: "RE: heavens-above advisory"

```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.

Russ,
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

>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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