Some time ago I saw a documentary on this Sky Disk from the Únětice Bronze Age culture in Germany circa 1600 B.C. Unfortunately, I am not well-versed in astronomy so will have to rely on links to best convey information about this artifact. It doesn't take a knowledge of astronomy, though, to understand how unique of a find this is.
The Nebra Sky Disk
Since the Nebra Sky Disk (also known as the Nebra Sun Disk) of Germany emerged into public knowledge in about the year 2000, archaeologists and astronomers have put forward their theories about how it worked and what it meant to the ancient society that fabricated it.
I have assessed it from the standpoint of the scientific knowledge that was encoded into ancient European megalithic sites or early edifices, such as those of the Giza Plateau, and so will now give an account of how I, personally, would have used this artefact as a memory device, based upon easily decipherable, ancient mathematical methodologies.The Mysterious Nebra Star Disk: Archaeological Wonder of Bronze Age Europe
But because no advanced civilization this advanced in astronomy had ever been found in Europe, many archeologists assumed that this was brought to Europe from the East by travelers or traders. By analyzing the copper and gold on the, however, scientists were able to verify that the disc was made in Europe and not brought from Egypt or Mesopotamia.
Looking closer at the disc, researchers began to recognize other parts of the picture. There is a curved line that is believed to represent what historians call a sun-ship, a prehistoric religious symbol that was thought to have originated in Egypt with the myth of the sun-god Ra. Golden bands on either side of the disc represented the solstices, with an angle that measures 82 degrees. It is only in that specific location, near the Mittelberg, in Germany, that the sun would rise and set at those particular angles on the solstices.I nearly had tears in my eyes because it came to as a surprise to all of us because we would imagine such a find in Egypt or Mesopotamia but not in central Europe, central Germany. And so it was fantastic to all of us and I nearly had tears in my eyes yes.
Decipherment of the Nebra Sky Disk as Depicting a Solar Eclipse at the Pleiades and the Vernal Equinox Point on April 16, 1699 - LexiLine Journal 394
(A different opinion on the astronomical significance)
According to the clear and incontrovertible evidence of the Latvian Dainas, which represent an archaic status of Indo-European astronomical knowledge in northern Europe, the Sun is in the solar boat by night only, and not by day. Hence, the Nebra Sky Disk can only represent the sky by day and thus the disk can only be the representation of a solar eclipse, since the Sun, Moon and Stars are all depicted together on the disk, something which occurs only during the rare phenomenon of a solar eclipse.
Wikipedia's entry for it
If authentic, the find reconfirms that the astronomical knowledge and abilities of the people of the European Bronze Age included close observation of the yearly course of the Sun, and the angle between its rising and setting points at summer and winter solstice. While Stonehenge and the Neolithic "circular ditches" such as the 5th millennium BC Goseck circle were used to mark the solstices, the disk is the oldest known "portable" instrument to allow such measurements.
Youtube also has multiple videos related to it that can be found with a simple search.