Venus.

Everyone knows that the planet Venus has the pentagram as its symbol right.
But why?

And how long has there been a connection between the star shape and the prettiest star?

Anything I write from this point on will reveal how bad I am at mathematics, nevertheless, I want to work this thing out.

So:  Venus goes 13 times around the sun for every 8 orbits of Earth. This must mean that Venus is in the same place in the sky (same date, same time) once every eight years I think...

Venus is linked to the Fibonacci series via the ratio of Earth's 13 to the 8 of Venus. The Fibonacci series describes the ratio that creates spiral sea-shells, or the pattern of seeds in a sunflower.

The Fibonacci numbers are: 0.1.1.2.3, 5, 8, 13, 21. So one could predict (but in my case can't see it!) that Venus would make some kind of pretty patten, or at least a regular pattern when observed. So it is that people say, Venus traces an almost perfect geometrical shape.

But not from where I'm standing.

Newton, on the other hand...could.
But he was very good at maths!

Four thousand years ago, the view from space (let alone the sure and certain knowledge that we were atop a ball of rock rotating around a star) wasn't available. The most logical way to solve this mystery of Venus as linked to a pentangle star-shape is to remain earth bound and look at sky maps showing the stars above me for the same day and time and location for eight years recording where Venus is, and then draw a line between them and see if it makes a star!

I have just done that, and convinced myself that I get a kind of warped five point star shape.

The Mesopotamian tablets that describes the movements of stars, sun and moon are known as The Enuma Anu Enlil.  Tablet 63 is the Venus tablet of Ammisaduqa, (1750 BC) mostly it describes Venus's position and provides something along the lines of 'red sky at night, shepherd's delight' information: 'Venus enters the sun, or Venus enters the furrow and the wind blows'. There is some discussion about the colour of clouds seen around Venus, but mostly we are in Old Moore's Almanac territory:

"The gods of the land will decide the case of the land for evil. Enlil will hang the plow of the land on a peg...."

The Enuma Elish which may have been written around the same time or after The Enuma Anu Enlil describes Marduk creating the heavens and the earth from the body of Tiamat with the stars as the domains of the gods, and setting out the order of their movements. Any disorder such as an eclipse (even though it was predictable) was considered to be unfortunate. The gods would purposely cause plagues and war, the signs in the sky meant that appeasement of the particular god whose star was signalling the warning, was possible and disaster could be averted.

We are no better off, from the Internet it appears to me that people are not too sure whether or not to believe that Venus has an effect on the economy, or a child born when Mercury and Venus are in the sky may be the Messiah, or if Saturn in conjunction with Mars causes earthquakes.

In Mesopotamia, 1100 BC, people had a theory that explained causation of dire events, and explained why the celestial event didn't always correlate with the predicted event.

We live in a time when the Popparian dictum of being able to falsify, but never to prove a theory, is supposed to reign. Each of us is supposed to enjoy science, enjoy uncertainty and to prefer boldly facing the unknown...But we are not very different from the people of Mesopotamia.

But, more often than not Ishtar/Inanna is shown holding rings in her hands, the loop symbol of a ring-headed doorpost. Sometimes she is shown with a star, but usually an eight point star (as in the eight years of it's rotation?) and not a pentagram.

So I don't see any strong connection with the deamonically satanic pentagram and Venus as Inanna.

Whilst there is certainly a connection between Inanna and the planet Venus; the Sumerian stories Inanna and Shu-kale-tuda: translation and The Descent can both be interpreted as linking her with the visible movement of the planet.

And prehistoric, Neolithic connections with the planet?
I've heard it said of Newgrange and Bryn Celli Dhu....