What do the colours surrounding the direction arrow mean? (iOS)

By default on the flip side page, there is an arrow which shows the direction to the next waypoint. The arrow might appear in different colours, depending on the status, as described below:

Green

You are moving and the GPS is providing your instantaneous direction of travel.

Red

You are stationary and direction is provided by the magnetic compass

Blue

You are going too slow for the GPS to measure direction and the compass is disabled. Direction is estimated by averaging the GPS position over time.