Title text:
If you don’t know where you are on Earth, the angle of satellite dishes can help constrain your latitude. If some of them are pointing straight up, you’re probably near the Equator, right under the ring.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3156/
Your use of the word “dense” there is a little misleading. At the default view the scale of each satelite pixel looks roughly 20km wide.