Science Channel's most watched series reveals Earth as it's never been seen before. Illuminating views captured by more than 4,000 orbiting satellites, `What on Earth?' investigates mysteries from strange geological occurrences to weird man-made structures. Every day, the eyes in the sky uncover new mysterious phenomena, and some defy easy explanation. To search for answers, the series combines modern imaging technology with analysis from military and intelligence professionals as well as leading scientists.
World's Deadliest Threats: Mysterious satellite images reveal China's hidden terror camps and provide access to America's top secret apocalypse pyramid. (S6, ep 1)
Monsters of Diamond Desert: Satellites capture unusual images including markings in the desert, while a strange symbol could be a portal into a lost South American civilisation. (S6, ep 2)
North Korea Death Star: Satellites capture startling images of a structure in North Korea that may be sinister evidence of a looming nuclear threat. (S6, ep 3)
Aliens of the Infinity War: Are unusual patterns in an English field really an alien message? And why is there a secret military facility in the Nevada desert? (S6, ep 4)
The Cave to Hell: Discover images of an Iceland cave that could hold alien secrets, military structures in the Utah desert and a bloody stain in the sands of Saudi Arabia. (S6, ep 5)
Terror of the Ice Snake: Discover a trail of moving objects in the ice of Antarctica, evidence of one of Joseph Stalin's most insane schemes and a code in the Sonoran Desert. (S6, ep 6)
Curse of Genghis Khan: A strange structure discovered in the Gobi Desert could reveal the whereabouts of lost treasure - changing everything we know about Genghis Khan. (S6, ep 7)
The King at Roswell: When a strange plane is discovered near the sight of the Roswell UFO incident, experts wonder if the aircraft has Nazi or extraterrestrial origins. (S6, ep 8)
Treasures of Monster Graveyard: At a mysterious site in the Gobi Desert, experts discover a monster graveyard - a groundbreaking find containing treasures of alien beasts. (S6, ep 9)
Cold War spy satellite photographs of mysterious structures hidden in Poland's forest motivate local archaeologist Grzegorz Kiarszys to hunt them down. (S6, ep 10)
A shipwreck in Lake Michigan has an incredible history. How did this vessel, once part of Hitler's push to win World War II, end up stranded in one of the Great Lakes? (S6, ep 11)
When satellites capture a massive crater in the picturesque English countryside, historian Martin Morgan heads there to investigate. (S6, ep 12)
A perplexing, intricate symbol high up in the remote Peruvian Andes may be for the grisliest of child sacrifices - death by lightning strike. (S6, ep 13)
When satellites capture a strange oozing grey mass in the Mississippi countryside, scientist Nick Pollock goes to investigate. (S6, ep 14)
Florida's vast Everglades have been invaded by up to 300,000 giant pythons. A group of military veterans are battling to rid paradise of these monsters. (S6, ep 15)
Satellites reveal a series of strange pits in central China. What are they and what is their connection to some of the most pivotal events in the country's history? (S6, ep 16)
Eyes in the sky uncover something disturbing in Alaska - a settlement large enough to house thousands of people, wiped out by artillery and bombs. What happened here? (S6, ep 17)
A strange, eerily colourful ocean seen from space conceals a terrible secret - its waters are killing all sea life in and around it. What is causing this dead zone? (S6, ep 18)
A mysterious explosion shakes a German village. When the culprit is identified as a dormant Nazi bomb, it triggers a hunt to rid a town of these deadly relics of World War II. (S6, ep 19)
Sometimes, the greatest mysteries revealed by satellites aren't what you can see, but what you can't. Why does a town appear on maps for decades, yet it is invisible from space? (S6, ep 20)