Heavenly Clockwork

And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years: And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so.
And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also.
And God set them in the firmament of the heaven to give light upon the earth, And to rule over the day and over the night, and to divide the light from the darkness: and God saw that it was good.
Genesis 1:14-18 KJV

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The writer of the first chapter of the Bible lives in what we today call a geocentric world.

From this point of view - that survived until the invention of telescopes in 16th century - we can understand the strange order of God's actions described here taking place during a week:
 
First Day God created heavens and earth and Light
Second Day God makes the oceans and dry land
Third Day God creates green plants that grow on land
Fourth Day God creates sun, moon and stars and places them in heavens in something translated to English as firmament.

Note that Light was the first thing to be created and this was done before and separately from the creation of sun and moon.

The creation story tells that God had two purposes in creating the greater and lesser lights - we see that both purposes are beneficial for man

• The great lights make the border of day and night and are signs for seasons, for days and years
• They give light during the day and night.

This is still true. Of course, today we do know just a bit more about the physical properties of sun and moon as we live in a world after the 16th century Copernican revolution. And yet, the two simple functions of sun and moon are still valid as described in the beginning of the Bible!

Days and nights
Biblical count of a day begins from sunset and ends in the next sunset as in the Creation story.

Rabbis define the beginning of Sabbath very carefully by observing when three stars become visible on the sky.  These are the times for Jerusalem on October 14/15:

Friday, October 14, 2011	Light Candles at: 4:29 pm
Shabbat, October 15, 2011	Shabbat Ends: 5:45 pm

In Biblical time night was divided into watches as watchmen stood on city gates and walls counting moments to sunrise. In New Testament period the day had literally "hours" Greek ὥρα  latin hora  from which the English word is derived.  "Noon time", latin nona hora... ninth hour.

Sun thus defines our days and nights. Today we divide the day with the help of our accurate watches into 24 hours keeping the ancient twelve plus twelve.

Although modern people much use kilo, hundred, thousand things, the ancient Jewish and Babylonian sixty system survives in our calculation of time - there are sixty minutes in an hour. We have later on added sixty seconds to minute when we were able to master the technology to determine such short time.

Months

The moon defines a month since ancient times by its waning, disappearance somewhere and new moon. However, calculating the length of lunar month is quite difficult.
A very human timer, menstruation, seems to be related to the moon although this is not mentioned in the Bible.


Seasons
Sun also defines the year and its repeating "seasons".

Today we have the knowledge and understanding of Nature to explain why there are the four seasons.

I am not sure how the Biblical writer understood מועד mo'ad. seasons or year or fixed times for festivals (full moon Easter) in relation with Sun and Moon. The yearly calendar was based mainly on the cycle of agriculture, rainy winter and dry sunny summer as in the Gezer calendar.

Sun dial
The Biblical sense of Sun determining the times of days is well present in sun dials that work by letting sun cast its shadow on a surface.

The sun dial of Ahaz was probably an observation in the palace following the shadow on some steps.
And this shall be a sign unto thee from the LORD, that the LORD will do this thing that he hath spoken;
Behold, I will bring again the shadow of the degrees, which is gone down in the sun dial of Ahaz, ten degrees backward. So the sun returned ten degrees, by which degrees it was gone down.
Isaiah 38:7-8 

This passage in the Book of Isaiah may be one of the earliest known descriptions of a watch... sun dial.



Divine power over sun and moon!
Then spake Joshua to the LORD in the day when the LORD delivered up the Amorites before the children of Israel, and he said in the sight of Israel, Sun, stand thou still upon Gibeon; and thou, Moon, in the valley of Ajalon.
And the sun stood still, and the moon stayed, until the people had avenged themselves upon their enemies. Is not this written in the book of Jasher? So the sun stood still in the midst of heaven, and hasted not to go down about a whole day. And there was no day like that before it or after it, that the LORD hearkened unto the voice of a man: for the LORD fought for Israel.
Jos 10:12-14 

For Martin Luther this Biblical event was clear evidence against that "foolish Nicolaus Copernicus" who claimed against common sense and the clear words of Bible that earth was supposedly rotating the sun!