We are starting a new chapter: Earth Magnetism — Page 49, Lesson 50

We are starting a new chapter: Earth Magnetism. This is a fundamental topic for navigation, because your compass doesn’t point to the true geographic North Pole — it responds to the Earth’s magnetic field. Let me walk you through the structure of what we’re about to cover. First, we begin with True Direction. That’s direction measured relative to the true geographic North Pole — the axis the Earth spins on. Then we move to Magnetic Direction, which is direction measured relative to the magnetic field. That brings us to Magnetic North — the point your compass needle actually points toward, which is not the same as true north. The difference between true north and magnetic north is called Variation. We’ll see how variation changes depending on where you are on the Earth — your observer’s position — and what happens at the poles, where the magnetic field lines behave differently. Then we look at the Real Variation Map, which is the actual charted pattern of variation across the globe, including the real variation at the poles. Variation also changes over time, so we cover Changes in Variation over Time and how we keep charts current by Updating Isogonals — those are the lines on a map that connect points of equal variation. Next, we have Magnetic Dip Angle. That’s the angle the magnetic field lines make with the horizontal surface of the Earth — it’s why a compass needle tilts as you move toward the poles. Then Deviation — that’s the error introduced by magnetic influences inside the aircraft itself, like electrical systems or metal structure. After that, we apply both variation and deviation together in Application of Variation and Deviation, which is how you convert between true, magnetic, and compass headings. Finally, the chapter closes with a Definitions section, then practice questions and answers. So, in this chapter, you’ll learn why your compass doesn’t point to true north, how to correct for that, and how to navigate accurately using magnetic references. Let’s begin with the first topic: True Direction.