28 The Sun and the Moon
Measurements along the Celestial Sphere
Astronomers use degrees, minutes, and seconds to measure distances across the sky or sizes. These are referred to as Angular Sizes: the angle the object appears to span or distance between objects, for example:
- 60 arcseconds = 1 arcminute
- 60 arcminutes = 1 degree
The Sun and Moon appear to be about ½ degree as we see them from Earth. This is not their true size; it is just how they appear to us.
←→ ½ degree = 30 arcminutes
But in the “Real Universe” the Sun is 400 times bigger than the Moon!