2008 marks the international effort to promote Earth Sciences. To celebrate this event, the world-renowned Pobjoy Mint has struck this unique coin featuring a silver outer ring, four-color inner titanium ring and silver center. The design represents the four spheres recognized in earth science: the lithosphere (earth); the atmosphere (air); the biosphere (fire); and the hydrosphere (water). The Greek Gods representing these elements are depicted in the titanium section, while the 12 Signs of the Zodiac are featured on the outer ring. The inner circle shows a map of the world.