[Lamarr]

I am sorry for the image size, the computer I was using was not capable of resizing it. To respond "How do I explain gravity" I explain it by simple physics, everything has a gravitational pull but it is dictated by the mass of the object. Why you may ask?, Because this is what happens to space and light its self around object with large mass. It has been studied and proven many times. Scientists at CERN, Nasa as well as the NSAU use these calculations to launch spacecraft into space.

As for how the image proves the earth is round, you're right it doesn't. However that image came from the ISS (international space station). Many people have been up there in LEO (low earth orbit) I will just name a few recent people who have gone: Chris Hadfield (Canadian) Alex Gerst (German) Andrew Thomas (American). If you ask anyone of them what the earth's shape is they will say round.