Because as the Earth rotates on its axis, it is the sky which APPEARS to revolve around the Earth each day. The Sun takes 365 days to travel a full circle across the sky in 360 degrees...or moves about 1 degree per day relative to the stars. On any given day it is in a specific zodiacal constellation and the whole shebang rises and sets each day.....honest. The is what the Copernican Revolution was all about over 300 years ago.