Calculate the average number of stars in your sample by adding all the sample numbers together and dividing by ten.

Learning Goal: I’m working on a astronomy discussion question and need an explanation and answer to help me learn.

In this assignment you will estimate the number of naked-eye stars that you can see in the sky. You will sample the sky in many different directions, by looking through a tube of some kind. A cardboard tube from a paper towel roll would work fine. You will then use your results in a formula that will estimate the total number of naked-eye stars in the sky at your location.

Place your tube against your eye socket without poking your eye out, and aim the tube at the sky. You don’t want to bias your sample by only pointing at bright, starry places in the sky, so point WITH YOUR EYES CLOSED. Open your eyes and count the number of stars you can see through the tube, and write it down. It might only be one star, or even zero. Don’t move the tube while you are counting; we don’t want any new stars coming into view. Aim the tube at a new location in the sky and count the stars. Take ten samples of stars in this way. Try to get samples from all over the sky: high, low, north, east, south, west, etc.

Calculate the average number of stars in your sample by adding all the sample numbers together and dividing by ten.

Measure the dimensions of your tube: length and diameter. Measure your dimensions in millimeters; that’s the easiest way.

The number of naked-eye stars in the sky can be estimated with this formula:

Number of stars in sky = (8 x L² / D²) x average number stars per sample,

Where L is the length of your tube in mm, and D is the diameter of your tube in mm.

Example:

Star samples: 1, 2, 0, 5, 4, 4, 3, 1, 2, 2

Average number of stars per sample = 24/10 = 2.4 stars per sample.

Diameter of tube: 50 mm. Length of tube: 350 mm (your dimensions will differ).

Number of stars in sky = (8 x (350)² / (50)²) x 2.4 = 941 (rounded).

Do your calculations exactly as I have shown, or I will have a cow.

To make this work, you are going to have to get away from the lights of the city, or you won’t see many stars. Drive east until you are lost. That should be far enough. Allow your eyes at least ten minutes to acclimate to the darkness, if you want to see some stars.

You must get to dark skies. No stars, no points.