home observation science solar system stars our galaxy cosmology astrobiology exoplanets astrophotography
How to measure objects in the night sky

If you look at star charts or almanacs, it is common to use degrees to indicate apparent size of an object, and apparent distances between objects.

Your hand can serve as a good ruler for measuring degrees. For example, an adult finger is about 1 across. The fist is about 10 across:

One finger: 1 Three fingers: 5 The fist: 10
Pinky and Index (Horns): 15 Pinky and Thumb (Hang Loose): 25  

Objects in the night sky can also serve as size references. The Full Moon is 1/2 in diameter. The images of the north and south poles on the previous page have a pair of stars circled: two stars of Ursa Major, and two Stars of Crux. These two are also good rulers: the space between the two Ursa Major stars are 5 apart, and the space between the two Crux stars are 6 apart.

Back to Top

Search | Site Map | Appendix
©2004 - 2024 Astronomy Online. All rights reserved. Contact Us. Legal. Creative Commons License
The works within is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.