It doesn't heat the earth. The source of all heat is the earth's core. The sun feels warm because it reflects some of this heat.
QED earth is flat.
The concept of a "core", or centre, is only possible on a round earth. And if this "core" is the north pole (which it must be in FE) then why is the north pole frozen. Haha got u narc
he obviously thinks there's a great magma doughnut buried beneith the equator 
The deeper you go underground, the hotter it gets. How is the sun the source of all heat if the earth is hotter deeper and cooler shallower? The heat comes from beneath, heating the lowest sections of earth more and the surface the least. Very high places, like tall mountains receive the least heat resulting in very cold temperatures. High altitudes, in flight, receive even less because the air transfers less heat to them. This is why it is cooler and cooler the higher you go.
That is unless you are an RE believer, where the sun heats everything making the core of earth very hot, but the surface very cool. It also makes the skies hotter and hotter the higher you go, the altitude of the ISS is 4000 degrees. How is the surface of earth the coolest place? The sun causes a directly competing double gradient of heat distribution? Are you kidding me?
FE is the only logical explanation.