Looking at the Stars

The entire sky around the Earth can be regarded as a sphere and, like all spheres, it has 41,253 sq. degrees.
About 6000 stars are visible to the naked eye. This means that, on average, each visible star occupies 41253 ÷ 6000 = ~7 sq. degrees, which converts into a circle of 3 degrees diameter.

It is difficult to imagine what a 3 degree circle looks like when you are looking at the night sky. But everyone knows the Moon and we can use the Moon as an aid to work it out. The Moon is about ½ a degree diameter, so look at the Moon and imagine lining up 6 moons. Use this line of 6 moons as a diameter to make a 3 degree circle. The area of the circle will be equal to 36 moons.

On average, that circle will have just one star. Half of all visible stars are 6th magnitude, so every second circle will contain a 6th magnitude star. But 6th magnitude stars are so faint that they are on the very limit of one's vision and it might be very hard to find or see them.

It gives one a shock to find how few and far apart are the stars and how empty the sky really is.

star field

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