How do you measure where objects are in the night sky?
To do this, astronomers possibly two thousand years ago adopted the degree as their unit of measurement. No one is sure which country the degree originated from or even why. Regardless of that, astronomers (and mathematicians) all agree that a complete rotation is made of 360 degrees (or divisions). A degree can also be divided into 60 further divisions (or minutes).
Use your hand
You can use your finger or hand to measure how close two stars are to each other. Just hold your hand up to the night sky and put it between two stars. For instance, if you can only fit a finger between the two, then they are approximately one degree apart.
Make a cross staff
Astronomers invented the cross staff to measure the night sky. Using a cross staff also avoids the fact that people have differing hand sizes or arm lengths. Make your own cross staff using only a 30 cm ruler and the ‘Cross staff angle arm’.
Download the file: Measuring_the_sky_cross_staff_angle_measurer