The opening ceremonies of the 2018 PyeongChang Winter Olympics were set in motion as five children exploring a mystical cave touched an ancient astronomical tool.

The armillary sphere is a revolving model of the celestial globe made up by rings and hoops once used by astronomers to plot the stars.

The stadium floor was soon filled with tiger, turtle, dragon and other guardian animal puppets from Korean mythology moving over the star chart which rose into a virtual reality dome of constellations. That chart was based on the world’s second oldest surviving astronomical map.

The Cheonsang Yeolchabunyajido, or Celestial Chart Stone, was carved in black marble in 1396 CE with the 1467 stars visible with the naked eye from Korea in varying sizes representing their brightness and names of important constellations.

An identical chart was engraved on the opposite side of the stone, upside-down.

Designated a National Treasure by the Korean government, it can be seen today in the National Palace Museum of Korea in Seoul.

Many Koreans handle their country’s astronomical history each day. The stone chart makes up the background of the Korean 10,000 won (currently a little more than $9 US) note. The bill also depicts an armillary sphere alongside the modern day 1.8 meter telescope at Bohyeonsan Observatory in central South Korea.