It's an old symbol, the pentagram, this star-shaped figure of the diagonals between the corners of a pentagon, at least it's very old compared to other symbols of similar complexity.
The oldest findings of it are from about 4000 B.C. in Palestine. It was a common symbol with the Sumerians from about 2700 B.C. The similar symbol, which by the way is much simpler to draw, the hexagram, is not found until about 800 B.C.
The probable reason for the earlier occurrence of the pentagram, is that it is a discovered symbol, in contrast to the hexagram, which is invented.
The form of the pentagram is constructed from the movement of the planet Venus on the ecliptic. Here's how:
Since Venus is closer to the Sun than the Earth, it will never come more than 48 degrees away from the Sun on the ecliptic. This means it will only be seen either early in the morning right before sunrise, then often called the Morning Star, or in the evening just after sunset, as the Evening Star.
The periods in which it is seen have a very regular pattern, unlike those of any of the other planets. Venus is visible as the Evening Star for 247 days. Then it moves in front of
the Sun for 14 days, before it again shows itself as the Morning Star for 245 new days. Then it disappears behind the Sun for 78 days and comes forth as the Evening Star again.
If you take the point on the Zodiac where the planet first shows itself as e.g. a Morning Star, then draw a line to the next point where it again comes forth as a Morning Star 584 days later, and repeat this until the sixth time, the last point will be nearly exactly at the first position. And the lines will form a beautiful pentagram. The time it takes for Venus to finish this cycle, is one or two days less than eight years.
Since the endpoints of the pentagram doesn't completely meet, the whole star rotates one degree every fourth year, in relation to the Zodiac. In 1460 years the pentagram completes one whole rotation. This was called a Sothis-year by the Egyptians, Sothis being the Egyptian goddess to which the planet Venus was ascribed.
The Central American civilizations were aware of the cycles of Venus. Both the Maya and the Aztecs used the planet's motion to establish both their calendars and their cosmogony.
The period between two first occurrences of Venus at the same point in the Zodiac, without regarding if it's in the morning or in the evening, is 1460 days, which is almost exactly four years, coinciding with the period between the ancient Greek and the modern Olympic Games. The five rings in the symbol for the Olympic Games, together with it's four year period, show the connection between Venus and the Olympic Games. In modern times this connection was evident in the logo of the 1984 Olympic Games in Los Angeles which mainly consisted of a five pointed star.