Depictions of the sky have been found on walls and ceilings that date back thousands of years. Other depictions are encoded in the layouts of monuments and burial sites. The oldest known portable view of the heavens is ancient as well — at least 3600 years old.
The Nebra Sky Disc was discovered 25 years ago, in Germany. It was buried with swords, axes, and other artifacts. The combination allowed archaeologists to date the burial of the cache to at least 1600 B.C., and possibly earlier.
The disc is a foot across and weighs more than four pounds. The front has a blue background inlaid with about three dozen features made of gold.
The features include a solid disc and a crescent. They’ve been interpreted as the Sun or full Moon, and a crescent Moon. There are also two gold arcs. One may depict a boat carrying the Sun across the sky. The other may show the Sun’s path across the sky from one solstice to the other. Finally, there are 32 smaller gold spots: the stars. Several of them form a tight grouping, which may represent the Pleiades star cluster.
There are many ideas about what it all means. The disc could have been a sort of calendar. On the other hand, it simply could have been decorative — an old and beautiful depiction of the heavens.
The Pleiades is high in the western sky at nightfall. Its brightest stars form a tiny dipper shape — a common landmark for skywatchers both ancient and modern.