Related by context. Frequent words. (Click for all words.) 56 Earth 53 planet 53 David Attenborough 47 Planet 47 Mother Earth 45 National Geographic 45 Earthlings 44 Shark Week 42 Discovery Channel 42 emperor penguins 41 Primeval 41 Sci Fi 41 boxset 41 humankind 41 Inconvenient Truth 41 planetary 40 polar caps 40 Sci Fi Channel 40 EARTH 40 Earthly 40 earth 40 oceans 40 Doctor Who 39 Antarctica 39 outer space 39 Extinction 39 An Inconvenient Truth 39 scifi 39 History Channel 39 Brainiac 39 Torchwood 39 Planets 39 Animal Planet 39 Dinosaurs 39 Global Warming 38 Nat Geo 38 Martian 38 sci fi 38 Battlestar Galactica 38 BBC2 38 Mythbusters 38 Universe 38 Grizzly Man 38 Humankind 38 Antarctic 38 Futurama 38 Bear Grylls 38 Martian surface 38 biosphere 38 Jane Goodall 38 Ice Age 37 Red Planet 37 mankind 37 DVD 37 Earths 37 mass extinctions 37 SciFi 37 Ozone Layer 37 Daleks 37 Civilisation 37 Oceans 37 Apes 37 Habitats 37 Stargate Universe 37 cosmos 37 Supernatural 37 Pink Floyd Dark Side 37 earths 37 Blu rays 37 SciFi Channel 37 Outer Space 36 Intergalactic 36 Arctic 36 Star Wars Clone Wars 36 Continent 36 Solar System 36 WALL E 36 Discovery 36 Crocodile Hunter 36 BBC4 36 Mars Rover 36 Stargate SG 1 36 Glaciers 36 Hubble Telescope 36 Deserts 35 dvd 35 global warming 35 Mars 35 biomes 35 alien invasion 35 wildernesses 35 sci fi horror 35 Red Dwarf 35 SCI FI Channel 35 Amazon rainforest 35 Whale Wars 35 Nature 35 Alpha Centauri 35 Roland Emmerich 35 Wonders 35 Sci fi