I don't believe in a magma filled ball Earth theory either. It simply has too many holes in it. When was the last time Copernicus'es model was proven with a physics experiment? It's funny how they demand you to prove your theory but refuse to prove theirs.
http://www.smarterthanthat.com/astronomy/top-10-ways-to-know-the-earth-is-not-flat/I saw a hyena once. They're much bigger than I thought they were.
Oh, just curious. How do you explain the Northern and Southern lights (Aurora Borealis and Aurora Australis)?
The sticks and shadows experiment was the only point I found interesting from that link. Is it really possible to calculate the circumference of the Earth like that? If so then it definitely kicks a hole into the flat earth theory. It doesn't puncture the concave earth theory though.
It's an old method and quite accurate.
But unfortunately, many of the other ways listed there were crap. The webpage even lists some of the stuff that is used to prove that the Earth is not convex. So it's laughable. For example, ships that have disappeared behind the horizon are still visible with a telescope, NASA photos are fake, centre of gravity could very well be in the middle of the hollow earth's crust not in the centre of the planet.
Since I think flat earth theory is weaker than the concave earth theory, hollow earth theory and expanding earth theory, I would not bother to explain some northern and southern lights thing. I'm not a flat earth believer anyway. I'm just an opponent of the Copernican system.
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.