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.
Strange mounds in Transylvania might pinpoint the location of the tomb of the bloodthirsty tyrant believed to have inspired Dracula. (S4, ep 1)
A massive hurricane heads toward Florida but something unexpected is in its eye and bizarre marks across the eastern US leave experts baffled. (S4, ep 2)
Strange markings could be a coded message with a plot to overthrow the Queen of England and a lake with healing powers holds clues to life on Mars. (S4, ep 3)
A ghost town covered in a strange, white power emerges from a lake in Argentina and a declassified CIA image uncovers a bizarre, giant Soviet weapon. (S4, ep 4)
When a man-made island mysteriously appears off the US coast, grisly new evidence points to secret government experiments into psycho-chemical warfare. (S4, ep 5)
A forbidden island points to a strange South American town that locals claim was the home of Adolf Hitler and a pit of bodies suggests fears of a zombie nightmare. (S4, ep 6)
When a labyrinth is discovered on an island once home to an ancient Greek civilization, experts investigate if it was the home of the Minotaur. (S4, ep 7)
Bizarre underwater formations might point to a top-secret US weapons testing facility and a strange sighting in the Arctic could be a lost Nazi relic. (S4, ep 8)
When a mysterious circular stone structure is discovered in Scotland, experts investigate whether it's the fabled Round Table of King Arthur. (S4, ep 9)
Experts investigate tunnels rumoured to be the hiding place of lost royal treasure, they find evidence of human sacrifice for Viking god Odin. (S4, ep 10)
Evidence might finally identify the hiding place of the billion-dollar Nazi gold train and blood-red river in Siberia points to catastrophic pollution. (S4, ep 11)
An ancient man-made volcano might reveal bloody human sacrifice and a mystery in the Sahara might have a sinister explanation. (S4, ep 12)
Man-made islands are spotted near a Korean missile facility and when something unexpected is found in a desert, experts investigate a lost city of giants. (S4, ep 13)
Adolf Hitler's secret UFO program Unknown, but ancient structure found in Eastern Ukraine, possibly created by the Arrata civilisation. (S4, ep 14)
A mysterious structure in Africa that resembles Stonehenge is said to be the resting place of a mythical giant. (S4, ep 15)
A mysterious Stonehenge-like structure in Russia might have links to the Nazis. Experts uncover clues to a mega-tsunami with the power to devastate the United States. (S4, ep 16)
When a great white shark is killed, experts suspect a mysterious ocean monster and strange markings in the desert might be a tribute to an ancient spider god. (S4, ep 17)
A strange mountain in Egypt sparks an investigation into Cleopatra's gems and the tomb of Alexander the Great. (S4, ep 18)
A ghost ship is found abandoned on a remote island that's home to one of the world's last uncontacted tribes. (S4, ep 19)
A strange structure shaped like a giant shark might point the way to a lost civilisation's Fountain of Youth. (S4, ep 20)