Is Halloween a purely earth-bound festival? The night’s theme of a time of when the two worlds, the spirit and the material, meet certainly has echoes in other strange phenomena, not least the claimed visits to our world by aliens.
Is it wishing too much to think aliens might have a calendar – and their own fancy dress costumes – up there? Perhaps Halloween, which is very ancient, is celebrating more physical spirits than we now like to emulate in our fancy dress costumes. Some UFO enthusiasts are certainly keen to link ancient tales of the Celtic Druids - to whom many attribute the origins of Halloween - to more advanced civilisations.
There are certainly plenty of examples of UFOs and aliens choosing to come a calling when the witches and sprites are also supposed to be lighting up the skies.
Sceptics will point to fireworks, party lights and Chinese lanterns that are used to celebrate this big party night, but here are five that have certainly convinced the experts.
Read on to discover some alien Halloween activity...