Planetary Alignment Decreases Gravity
In 1976, it was announced on BBC Radio that the planet Pluto would pass behind Jupiter at exactly 9:47 AM causing a decrease in the Earth's gravity. The radio station told listeners to jump in the air at the precise time to experience weightlessness. Listeners called in explaining that they had felt the floating sensation and one woman even claimed that her and her friends had risen from their chairs and floated.
Click here to see more Astronomy-themed April Fool's Day pranks on Museum of Hoaxes