Source: http://www.atlasobscura.com/articles/an-...

With its patinated bronze background and shiny gold sun, moon and stars, the 3600-year-old Nebra Sky Disc is worth gazing at for its beauty alone. But the ancient object is cool for a lot of other reasons: It’s the earliest depiction of outer space we’ve ever found, and it’s also thought to be the oldest known portable astronomical instrument.

For as long as humans have stared at the sky, we have sought to understand our place in the cosmos. This lovely orb is one of a long line of attempts of humans to map the unmappable—space. Scientists posit that the Bronze Agers who made the disc used it as an “astronomical clock” to correct for the shortcomings of moon-based calendars. Because the moon goes through twelve cycles every 354 days, not every 365, early agriculturalists had to throw in an extra leap month every once in a while to keep lunar calendars in sync with earthly seasons. They knew to add the extra month when the moon and the Pleiades were arranged “exactly as they appear on the Nebra sky disc.”