Quite often we will need to find
of some object, given its
Note – the book leaves out the units of “arcsec”.
Do not make that mistake yourself.
An example different than the one in the book:
How large is the sun?
The angular diameter of the sun is about 0.5
To convert that to arcseconds use:
60 arcsec/arcmin = 1800 arcsec
The sun is 1.5
km away (= 1 astronomical unit).
From our text:
Horizons, by Seeds
I can derive this formula in class if there is sufficient interest – ask me!