1. What is Magnetic Declination?

Magnetic declination is the angle between magnetic north (the direction the compass needle points) and true north (the direction along Earth's surface towards the geographic North Pole). This angle varies by location and changes over time.

2. How Does the Calculator Work?

The calculator estimates magnetic declination using:

Where:

• \( \delta \) — Current magnetic declination
• \( \delta_0 \) — Base declination for the location
• \( \frac{\Delta\delta}{\Delta t} \) — Annual rate of change
• \( year \) — Target year
• \( year_0 \) — Base year

Explanation: The equation accounts for the secular variation of Earth's magnetic field over time.

3. Importance of Magnetic Declination

Details: Accurate declination values are crucial for navigation, surveying, and any application requiring precise directional measurements. The difference between magnetic and true north can lead to significant errors if not accounted for.

4. Using the Calculator

Tips: Enter latitude (-90° to 90°), longitude (-180° to 180°), and year (1900-2100). The calculator will estimate the magnetic declination for that location and year.

5. Frequently Asked Questions (FAQ)

Q1: How often does magnetic declination change?
A: Declination changes continuously, though typically by small amounts each year (0.1°-0.2°). Some locations change more rapidly than others.

Q2: Why does magnetic north move?
A: Earth's magnetic field is generated by fluid motions in the outer core, which are dynamic and cause the magnetic poles to drift over time.

Q3: How accurate is this calculator?
A: This provides an estimate. For precise measurements, consult official geomagnetic models or recent surveys for your specific location.

Q4: When is magnetic declination most important?
A: Critical for navigation over long distances, surveying, aviation, and when using maps with compasses. Less important for short-distance navigation.

Q5: How do I adjust my compass for declination?
A: Either adjust your compass physically (if it has this feature) or mentally add/subtract the declination angle from your compass readings.