Let me orient you — Page 449, Lesson 426

This is a table of sunrise and sunset times — a page from the General Navigation manual that you'll use for celestial navigation and for flight planning when you need to know daylight hours at a given latitude and longitude. Let me orient you. The page is a grid. Down the left-hand side you have latitude values — I can see N 50, N 20, N 10, then 0, then S 10, S 30, S 52, S 60. So the rows run from 50° North down through the Equator at 0°, and on down to 60° South. That's your latitude axis. Across the top you have longitude values — 22, 23, 24, 25, 26, 27, 28, 29, 30 — running in degrees. So each cell of the table gives you a time value for a specific combination of latitude and longitude. Now, what are those times? Look at the numbers. At the top, near N 50, you see values like 20 21, 20 26, 20 30, 20 35 — those are minutes past the hour, in UTC — Universal Time Coordinated. So the entry "20 21" means 20 hours 21 minutes UTC. These are the sunrise and sunset times expressed in UTC for that latitude and longitude. Here's the key structure: for each latitude row, you get two sets of times. The first set — the ones I just read — are the sunrise times. The second set, further along the row, are the sunset times. So at N 50, you see sunrise values around 20:21, 20:26, 20:30, and then later in the row you see sunset values like 21 00, 21 07, 21 14 — those are the evening times. Let me trace one row so you see the pattern clearly. Take the N 50 row. The sunrise times run from about 20 21 down to about 20 58 as you move across longitude. Then the sunset times pick up — 21 00, 21 07, 21 14, and so on up to about 21 53. So for a given longitude, you read the sunrise time from the first part of the row and the sunset time from the second part. Now look at the S 60 row at the bottom. The sunrise times are around 16 26, 16 20, 16 16 — and the sunset times around 15 55, 15 56, 15 58. Notice something important: at high southern latitudes, the sunset time is earlier than the sunrise time in UTC. That's because of the time-zone offset — the sun rises and sets at very different clock times in the Southern Hemisphere compared to the Northern. The table gives you both, in UTC, so you can convert to local time for your flight planning. Here's how you actually use this in navigation. You enter the table with your latitude and longitude. You read off the sunrise time and the sunset time in UTC. From those two values you can compute the duration of daylight — the difference between sunset and sunrise. That tells you how many hours of daylight you have for your flight, which matters for visual flight rules operations, for planning when you need to be on the ground, and for celestial navigation — knowing when the sun is up for sun shots, or when you'll have stars available at twilight. One more thing to notice: the table is symmetric in a sense. Look at the N 10 row and the S 10 row. At N 10, sunrise is around 18 53, 18 55, 18 56 — and at S 10, sunrise is around 18 08, 18 08, 18 07. The values are close but not identical, because the table accounts for the equation of time and the obliquity of the ecliptic — the tilt of the Earth's axis. So you can't just flip the sign of latitude; you must read the actual row. Let me also point out the 0° latitude row — the Equator. There you see sunrise around 18 41, 18 42, 18 43 and sunset around 18 45, 18 46, 18 47. At the Equator, day and night are nearly equal — about 12 hours each — and the table reflects that: sunrise and sunset are almost the same time, roughly 18:45 UTC for that longitude. So, to summarise the structure: rows are latitude (from 50°N down to 60°S), columns are longitude (from 22° to 30°), and each cell gives you a time in UTC — the first part of each row is sunrise, the second part is sunset. You use it to find daylight hours for a given position, which is essential for flight planning and celestial navigation. That figure shows you the geometry behind it — how True North is defined by the line joining your position to the North Pole, which is the reference for all your direction and time calculations. The table you're looking at is the practical tool that turns that geometry into actual clock times for your flight.