Thread: Measuring size
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Old 24-09-2016, 11:23 AM
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billdan (Bill)
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Join Date: Mar 2012
Location: Narangba, SE QLD
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Gooday David,

In astronomy we usually only speak of angular size, which is the angle of an arc of a circle and then absolute size can be worked out from this formula.

absolute size = distance * tan(angular size)

Or you can work out the length of the circumference by using 2*pi*distance and then divide that length by 21,600 to give you the length of 1 arcmin. So if your angular size of the object was 5 arcmin then multiply your result by 5 to get absolute size.

Clear as mud


Last edited by billdan; 24-09-2016 at 11:41 AM.
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