Planet - Wikipedia, the free encyclopedia
1 History 1.1 Babylon 1.2 Greco-Roman astronomy 1.3 India 1.4 Medieval Muslim astronomy 1.5 European Renaissance 1.6 19th century 1.7 20th century 1.8 21st century 1.8.1 Extrasolar planet definition 1.8.2 2006 definition 1.9 Objects formerly considered pl...