When you add a third satellite (satellite with a blue sphere) you can come close to finding your exact position on the Earth. Imagine that you are 14,000 miles from the third satellite. In this situation, there are only two points (the two white points) where you could possibly be. These points are where the 14,000-mile sphere intersects with the 15,000-mile and 12,000-mile spheres. Click on the arrow below
to see what happens when you add another satellite.