1972: The Body of Nessie Found
On March 31 1972, a team of zoologists from Yorkshire's Flamingo Park Zoo, who were at Loch Ness searching for proof of Nessie's existence, found a mysterious carcass floating in the Loch. Initial reports claimed it weighed a ton and a half and was 15 1/2 feet long. The zoologists placed the body in a van and began to transport it back to the zoo. However, the police chased down their truck and stopped it under a 1933 act of Parliament prohibiting the removal of "unidentified creatures" from Loch Ness. The body was then taken to nearby Dunfermline for examination. The discovery of the carcass received worldwide media attention. The British press dubbed it "Son of Nessie." But upon examination, Edinburgh scientists identified the creature as a bull elephant seal from the South Atlantic. The next day John Shields, Flamingo Park's education officer, confessed he had been responsible for the body. The bull elephant seal had died the week before at Dudley Zoo. He had shaved off its whiskers, padded its cheeks with stones, and kept it frozen for a week, before dumping it in the Loch and then phoning in a tip to make sure his colleagues found it. He had meant to play an April Fool's prank on his colleagues, but admitted the joke got out of hand when the police chased down their van.
1976: Planetary Alignment Decreases Gravity
The British astronomer Patrick Moore announced on BBC Radio 2 that at 9:47 AM a once-in-a-lifetime astronomical event was going to occur that listeners could experience in their very own homes. The planet Pluto would pass behind Jupiter, temporarily causing a gravitational alignment that would counteract and lessen the Earth's own gravity. Moore told his listeners that if they jumped in the air at the exact moment that this planetary alignment occurred, they would experience a strange floating sensation. When 9:47 AM arrived, BBC2 began to receive hundreds of phone calls from listeners claiming to have felt the sensation. One woman even reported that she and her eleven friends had risen from their chairs and floated around the room.
1989: UFO Lands in London
On March 31, 1989 thousands of motorists driving on the highway outside London looked up in the air to see a glowing flying saucer descending on their city. Many of them pulled to the side of the road to watch the bizarre craft float through the air. The saucer finally landed in a field on the outskirts of London where local residents immediately called the police to warn them of an alien invasion. Soon the police arrived on the scene, and one brave officer approached the craft with his truncheon extended before him. When a door in the craft popped open, and a small, silver-suited figure emerged, the policeman ran in the opposite direction. The saucer turned out to be a hot-air balloon that had been specially built to look like a UFO by Richard Branson, the 36-year-old chairman of Virgin Records. The stunt combined his passion for ballooning with his love of pranks. His plan was to land the craft in London's Hyde Park on April 1. Unfortunately, the wind blew him off course, and he was forced to land a day early in the wrong location.
2008: Flying Penguins
The BBC announced that camera crews filming near the Antarctic for its natural history series Miracles of Evolution had captured footage of Ad'elie penguins taking to the air. It even offered a video clip of these flying penguins, which became one of the most viewed videos on the internet. Presenter Terry Jones explained that, instead of huddling together to endure the Antarctic winter, these penguins took to the air and flew thousands of miles to the rainforests of South America where they "spend the winter basking in the tropical sun." A follow-up video explained how the BBC created the special effects of the flying penguins.
(Source: http://theunexplainedmysteries.com/Top-20-April-Fool-Hoaxes.html)
