A circle is drawn from the center of The WORLD! The center of the world in this case is defined as 0,0 N and 0,0 E. Using a standard Mercator projection this is in the Gulf of Guinea as the picture shows.
It is 4453 km in radius (2767 miles). Which is a ninth of the circumference of the Earth.
What countries does it go through?
Only the countries that the 4453 km line goes through count.
For example: Ivory Coast does not count as it ranges from 662-1380 km.
For example: Canada does not count as it is more than 4453 km away.