[billdan (Bill)]

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

Bill