Why seven days?
This blog has always been an iconoclastic one so I am sure a little bit more iconoclasm will not hurt.
Most people seem to think that there are seven days in the week because it says so in Genesis. That is not so. There were seven days in the week long before either of the two creation accounts in Genesis were written. The account mentioning 7 days (from the first verse up to chapter 2 verse 3) is in fact a later add-on. The original creation account in Genesis (from chapter 2 verse 4 onwards) says that the heavens and the earth were created in ONE day! And, yes, I do know the theological ways of getting around that. They are theological rather than scholarly, though.
But at any event, the division of the week into 7 days is very ancient. The later Genesis writer was just setting up a Hebrew story to explain a long-standing pagan custom. The custom goes back to those great stargazers, the Babylonians (and possibly further back to their Sumerian predecessors). Mesopotamia is basically desert -- made habitable by irrigation. So when you look up into the sky at night there the stars are very bright. And with no TV, movies or internet that is about all you had to look at during night-time way back then.
And the most striking thing you notice about the stars is that their position in the sky is very fixed -- EXCEPT for just five pesky stars that move about. I don't know the Babylonian names for them but we call them Mercury, Venus, Mars, Jupiter and Saturn -- which are the Roman names for them (more or less). They are of course planets, not stars. But the Babylonians didn't know that so they thought it was obvious that they must be gods. Who else could move about among the stars? So we clearly have five gods there.
But there are two OTHER moving objects in the sky -- the Sun and the moon -- with the sun obviously being the big chief. So if there are 7 gods (5+2), to be on the safe side each one had to have day devoted to him/her. One could not risk offending a god. So the 7 days of the week were named after the seven movable objects that the ancient Iraqis could see in the sky!
And because the sun was clearly the big guy he had to have the FIRST day of the week named after him and have that day especially sacred. And we perpetuate that to this day. We still see Sunday as special.