Exodus 20:11 (KJV) For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.
Years, months, & days all have basis in astronomy. But the 7 day week is only found in the Bible. If you are one of those who are trying to remove God and the Bible from everything, then you better get rid of the seven day week. If you don’t, you still will be following what God established.