Quote from: Fatman3001 on December 29, 2015, 11:47:58 PM

https://en.wikipedia.org/wiki/Eratosthenes#Measurement_of_the_Earth.27s_circumference

It's an old method and quite accurate.

Quote

Eratosthenes' calculations are not proof of any particular model, but based on an assumption of which earth model is correct.

reference: http://www.theflatearthsociety.org/tiki/tiki-index.php?page=Eratosthenes+on+Distance+of+the+Sun

Quote from: Fatman3001 on December 29, 2015, 11:47:58 PM

The reason I ask about the Northern and Southern lights is because in conventional physics it is believed that these phenomena are the result of the interplay between the Earths EM field and massive particles slung out from the sun. It is quite well understood and basically means that you can use solar "weather forecasts" (since light moves faster than particles with mass) to tell you if/when there will be northern/southern lights appearing. But in order for this to be true, something needs to create the EM field. A spinning liquid metal core; which doesn't fit well with your hollow earth assumption.

the hollow earth theory has actually an answer for this. Inside the hollow earth there is a hot iron core which provides heat and light for the inner Earth and which also provides the protective magnetic field for the outer Earth.

http://www.collective-evolution.com/2013/08/26/mind-blowing-research-suggests-that-earth-could-actually-be-hollow/

This central sun is not a conventional sun (there are no thermonuclear reactions taking place) but instead it is a hot ball of iron.

I would recommend you browse this blog for more answers regarding the hollow earth theory:
http://hollowplanet.blogspot.nl/

It is written by a scientifically minded person rather than by some religious lunatic.