🔍 Key Concepts

• Greenwich Hour Angle (GHA) definition and how it is measured from the Greenwich meridian • Relationship between GHA and geographic longitude (east vs. west) • How values between 0° and 360° of GHA correspond to east or west longitude

💭 Think About

• Ask yourself: When GHA is between 0° and 180°, what direction (E or W) is the longitude, and when it is between 180° and 360°, what happens? • Think about how to convert a GHA greater than 180° to an equivalent longitude: what simple subtraction might you perform, and what does that do to the direction? • Compare the numerical value of the resulting longitude with the choices: which ones have the correct magnitude and which have the correct E/W designation based on your conversion?

✅ Before You Answer

• Be sure you know that GHA is always measured westward from Greenwich (0° to 360°) • Confirm whether a GHA greater than 180° corresponds to an east or west longitude after conversion • Double-check your arithmetic when subtracting from 360° and that you keep minutes (') handled correctly when doing that subtraction