Because men do not believe the Word of God about the sun's creation and purpose they make up stories about it.
Wait, what? Even if you believe that the sun was created by a sky daddy, then you can acknowledge that the Earth rotates.
The sun is not what earthlings who deny the Word of God as true say it is; neither in composition, size, distance, or purpose.
We've measured the distance, the size and the composition with satellites. As far as purpose, it provides warmth (even on the coldest day it provides it) and without it the Earth and all it's life would not exist due to the masses wouldn't have come together.
Earthlings have not measured it, tested it, or visited it; and men who make claims about what they cannot test, handle, or examine inside and out are foolish indeed.
Read my previous debunking for about how we have measured, how far, composition. Also you can't hold the sun in your bare hands, you'd fry and due to the fact that the sun is roughly 865,000 miles (1,392,000 km) in diameter, or roughly one million earths could fit inside it for it's volume.
God made it on day four of creation to "rule/govern" the created light of day one, and set it in the heavens on an orbit/path/circuit from one end of heaven to the other.
Wait. So God made the sun to govern the light made on day one, when it wasn't made till day four? How is that possible? Did the light magically go back in time? Also that path idea sounds a lot like the Greek belief that the sun was driven by a chariot racing across the sky.
Enoch was shown the entire created universe and you can read what he was shown in the book of 1 Enoch [Ethiopian Enoch], in the astronomical book.
I thought that the Book of Enoch wasn't considered part of canon and it's writer is falsely attributed to Enoch.
Acording to Enoch, the sun is the same size as the moon -exactly- but it is the gatherer of the light of day one, and that light is sent out mightily by the sun from one end of heaven to the other, as the Word of God states, in its orbit around the earth.
Well the sun isn't the same size as the moon, hell the moon isn't even half as big as Earth. You'd fit right in the Bronze Age when the bible was written.