Let me orient you to the structure, because that's the key to reading it — Page 449, Lesson 429

I want to walk you through what this page actually is, because at first glance it just looks like a wall of numbers. This is a sunset table — a tabulated prediction of the local mean time of sunset for a range of latitudes and dates. It's the kind of data you'd use in general navigation to work out daylight hours, plan a night-flight transition, or check whether you'll still have legal daylight at your destination. Let me orient you to the structure, because that's the key to reading it. The table is organised by latitude, and the latitudes are listed down the left-hand side. You can see entries like S 10, S 30, S 52, S 60 — those are southern latitudes, 10°S, 30°S, 52°S, 60°S. And on the right-hand side you have N 72, N 70, N 68, N 66, N 64, N 62, N 60 — northern latitudes. So the table spans both hemispheres. The columns across the top are dates. Look at the header row: it runs June, then July, then August, with day numbers beneath — 1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31, then 3, 6, 9, 12, 15. So the table gives you sunset times at three-day intervals across those months. Now, the times themselves. Each entry is in hours and minutes — you'll see values like 23 08, 22 33, 21 43. That's 23 hours 08 minutes, 22 hours 33 minutes, 21 hours 43 minutes. These are the local mean times of sunset for that latitude on that date. Here's the important part — the G entries. You'll see a lot of cells containing just the letter G. That stands for "G" — continuous daylight, meaning the sun never sets at all on that date at that latitude. For example, at N 72 you see G across nearly the whole row, and only near the end of August do actual times appear — 23 08, 22 33, 22 06, 21 43. That makes sense: at very high northern latitudes in June and July, the sun stays above the horizon around the clock. The G is telling you there's no sunset to record. Let me trace one row so you can see the pattern. Take N 60. On June 1st the sunset is 21 27. As the days progress — June 4th 21 25, June 7th 21 23, June 10th 21 20 — the times get earlier. By late June it's 21 06, 21 01, then into July 20 55, 20 48, 20 41, and by mid-August 20 27, 20 19, 20 11. So the trend is clear: after the summer solstice, sunset gets progressively earlier each day, and the table captures that drift in three-day steps. Now look at the southern latitudes — S 10, S 30, S 52, S 60. The times there are in the 06 and 07 and 08 hour range — like 06 56, 07 09, 08 10. That's because it's winter in the southern hemisphere during June, July and August, so the days are short and sunset is early in the afternoon. And notice the trend is reversed: as the months progress, the southern sunset times get later — from 06 56 in early June at S 30, drifting to 07 39 by late June, and into the 08 hour by August. The southern hemisphere is moving toward spring, so days are lengthening. There's also a SUNSET label at the top of the table, and a Lat. column header — that's latitude, the row variable. So the whole page is a two-way lookup: pick your latitude, pick your date, and read off the local mean time of sunset. One thing I want to be careful about — this is a raw data table, so I'm not going to invent a formula or a rule that isn't printed here. What I can tell you is how to use it: you enter with your latitude and your date, and you exit with the sunset time. The G tells you there's no sunset — continuous daylight. And the progression of times across the columns shows you the seasonal drift of sunset, earlier in the northern summer, later in the southern winter. That's the whole page — a latitude-versus-date grid of sunset times, with G marking the polar daylight zones.