#3: When you show charts of the sky, how much sky am I actually seeing?

Excellent question since, without a sense of scale, it’s hard to find what you’re looking for. The image below shows a scale of degrees superimposed over the standard sky chart you see in pre-2014 Sky Lights. The use of the human hand to measure degrees is surprisingly accurate. Sure, some people have larger hands, but then, they also tend to have longer arms, so the difference cancels out. This is still a useful way for estimating distances in the sky, even though in early 2014 we switched to using Cartes du Ciel (Sky Chart) to do all our mapping. It automatically overlays a degree grid to provide scale information.

<img src=”http://sky-lights.org/wp-content/uploads/2011/07/scale.jpg”>