It helps if, like the Panorama programme (see spaghetti tree post), an April Fool hoax is from a usually honest and reliable source. Such as the esteemed British astronomer Sir Patrick Moore.
In 1976 Sir Patrick Moore told listeners of BBC Radio 2 that the unique alignment of the planets Jupiter and Pluto would result in an upward gravitational pull, making people lighter at precisely 9:47 am that day. At that exact time, on the radio, Moore told the audience to jump into the air and experience “a strange floating sensation”. Dozens of listeners phoned in to say the experiment had worked. Actually, Pluto is so small it could never have any effect on Jupiter, or any other planet.