The "N" means north latitude, and the number is the degrees of latitude — Page 449, Lesson 429

I want to walk you through what we're looking at here, because this is one of those pages that looks like a wall of numbers until you understand the grid you're reading. What we have is a sunset table — a tabulated set of data that gives you the time of sunset at a given latitude for each day of the summer months. This is a standard piece of navigation data you'll find in the almanac section of your general navigation material, and it's used for planning flights where daylight, twilight, or night conditions matter. Let me orient you to the structure first, because the layout is the key to reading it. The table is organised by latitude, and you'll see the latitude values running down the left-hand side. I can see entries for N 72, N 70, N 68, N 66, N 64, N 62, and N 60 — so these are northern latitudes, from 72 degrees north down to 60 degrees north. The "N" means north latitude, and the number is the degrees of latitude. Across the top, the columns are the months and days. I can see the month headers June, July, and August, and beneath each month there's a row of day numbers — 1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31 for June, then continuing into July and August. So each column is a specific calendar date. Now, the body of the table — the numbers in the cells — are the times of sunset, expressed in hours and minutes. You'll see them written in the form like 23 08, which means 23 hours and 08 minutes, or 21 27, which is 21 hours and 27 minutes. These are the local times at which the sun sets on that date at that latitude. Here's the critical thing to understand about how this table behaves: as you move down the table to lower latitudes, the sunset times get earlier. Look at the pattern. At N 72, you're seeing times around 23 hours — very late sunsets, because you're at high latitude in summer where the days are extremely long. By the time you get down to N 60, the times have come down to around 21 hours — still late, but noticeably earlier. That's the latitude effect: the higher your latitude in summer, the later the sun sets. There's also a day-to-day trend within each latitude row. If you follow a single row across the days of June into July and August, you'll see the sunset times getting progressively earlier as the summer advances and the days shorten after the solstice. The numbers step down gradually — you can see it in the N 60 row, where the times decrease steadily from the June columns through to August. Now, there's one more feature I need to point out, and it's important because it's a special notation. In the high-latitude rows — N 72, N 70, N 68, and N 66 — you'll see the letter G appearing in some cells instead of a time. That G stands for a specific condition, and it's telling you that at that latitude and date, the sun does not set at all — it's the period of continuous daylight, what we call the midnight sun. When the table shows G, there is no sunset time to record because the sun stays above the horizon for the full 24 hours. You'll notice the G entries appear in the June columns at the highest latitudes, and they disappear as you move to lower latitudes and later in the summer — because the period of continuous daylight only exists at high latitudes and only around the summer solstice. Let me also point out the SUNSET label at the top of the table — that's simply confirming what the entire table is giving you, the time of sunset for each latitude and date combination. And you'll see some latitude markers like S 10, S 30, S 52, S 60 scattered through the data — those are the southern latitude rows, the mirror image of the northern ones, giving you the same sunset information for southern latitudes. So, to summarise how you'd actually use this: you find your latitude on the left, you find your date across the top, and where the row and column meet, you read the time of sunset — unless you see a G, in which case the sun doesn't set that day. That's the whole logic of the table, and once you see the grid, the numbers stop being a wall and start being a quick reference for planning your daylight operations.