Edinburgh many museums and libraries. These include the National Museum of Scotland, the National Library of Scotland, National War Museum, the Museum of Edinburgh, Surgeons' Hall Museum, the Writers' Museum, the Museum of Childhood and Our Dynamic Earth. The Museum on the Mound has exhibits on money and banking. Edinburgh Zoo, covering on Corstorphine Hill, is the second most popular paid tourist attraction in Scotland, and currently home to two giant pandas, Tian Tian and Yang Guang, on loan from the People's Republic of China. Edinburgh is also home to The Royal Yacht Britannia, decommissioned in 1997 and now a five-star
Tian "Canopy-Heavens hypothesis" originated from the text Zhoubi Suanjing. The earth is covered by a material tian. "Huntian shuo" (渾天說) "Egg-like hypothesis". The earth surrounded by a tian sphere rotating over it. The celestial bodies are attached to the tian sphere. (See , Chinese creation myth.) "Xuanye shuo" (宣夜說) "Firmament hypothesis". The tian is an infinite space. The celestial bodies were light matters floating on it moved by "Qi". A summary by Ji Meng (郗萌) is in the astronomical chapters of the Book of Jin. Sometimes the sky is divided into "Jiutian" (九天) "the nine sky divisions", the middle sky and