Because the circumference of the earth spins at an 80° angle around. The sun witch is 40000000° F and as it spins if the population of the earth goes down below 7 billion then the earth will drift away from the sun to a new galaxy lol it did in 5000 B.C. in the great marijuana war and then um well yeah I just made all of this up even the heat of the Sun instead of looking it up so yeah.