Photoshopped NASA Images

Hopefully I can explain what I'm looking at here.  This is an image I took from NASA's website.  People think they are looking at a beautiful photo from space.

So I took a measurement of the distance across Mexico near Mexico City that you can pick out on this globe image.  Measurements on google maps match up with what we measure on our cars.

So the distance across Mexico at this point is about 577 miles.  I will use half the circumference of the earth as the distance it should be across that globe image, which is about 12450 miles.  So this distance across Mexico should be 12450/577 or about 1/21 of the whole distance across the globe.  So if we mark out the distance across Mexico on the globe image, we should be able to put about 21 of the same distance to get from one end of globe to the other.  Instead we get ~7?  That's not even close.