Coding classes in Dumfries and Galloway

The learner downloads the Yale Bright Star Catalogue, which lists the brightness and position of every star bright enough to see without a telescope: 9,096 entries with both values. Astronomers measure brightness in magnitudes, where bigger numbers are fainter, and the usual naked-eye limit under a dark sky is around magnitude 6 to 6.5. First the program counts stars brighter than each magnitude, and a pattern jumps out: each step fainter roughly triples the count, from 174 stars brighter than 3 to 518 brighter than 4, 1,630 brighter than 5 and 5,080 brighter than 6.

Now the claim. From Galloway, at about 55 degrees north, stars far enough south never rise, so the program keeps only those with a declination above minus 35 degrees: 6,814 catalogue stars. But at any single moment only the half of the sky above you counts. Using a little spherical geometry to work out each star's height, the program finds on average about 4,074 stars brighter than magnitude 6.5 above the horizon at once, and about 3,387 if the murky lowest ten degrees are left out. Seeing over 7,000 would need a different definition: counting over the whole year, including planets, or seeing stars fainter than 6.5 under an exceptional sky.

That is the real lesson. The claim may well be true in the sense its authors intended; our program cannot tell. What it does show is that a number like "over 7,000 visible" means very little until you know over what time, down to what brightness, and from what height above the horizon. Making those choices explicit, and seeing how much each one moves the answer, is exactly what data work is.

So a young person in Dumfries and Galloway should learn to code in 2026 to find out what a number really counts. The longer argument is in why teenagers should still learn to code in 2026.