A photograph showing a strange, cigar-shaped object over the top of Mount Washington showed what appeared to be an alien spacecraft - in 1870.
Debate has reignited this week over what may be among the oldest evidence of alien visitors to our world.
The picture, taken with a stereo photography camera (used at the time to create images with an illusion of depth, when viewed through a special stereoscope) is thought to be near-impossible to fake or manipulate.
Expert analysts have recently come up with new theories of the origin of the strange craft - but agree that the image is real, dated correctly and not manipulated.
The image contained tantalising clues about the otherworldly craft - some claimed it was a huge mothership, from which smaller UFOs would have descended.
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Others claimed to be able to pick out a swastika emblem on the side of the craft - and UFO websites and magazines have debated the picture endlessly since it resurfaced in 2002.
When the picture went for sale on Ebay, a cinema mogul, Samuel M. Sherman the president of Independent-International Pictures Corps, won the auction - and promised to have it scientifically studied.
A UFO researcher has come up with a new theory as to what is on display in the dual image - and he claims we can rest easy in our beds, at least where time-travelling extraterrestrial Nazi spacecraft are concerned.
Ryan Mullahy the founder of the New Hampshire UFO Research website wasn’t impressed with the picture, and decided to do some further research.
As UFO enthusiasts have claimed, the picture is genuinely from 1870 - and it has not been retouched or manipulated in any way.
Mullahy found that it was a heavily cropped picture of an image titled, Frost Architecture taken by Amos Clough and Howard Kimball whilst on a meteorological expedition in the winter of 1870 to 1871.
Their pictures were given wide distribution and they even wrote a book about their adventures, ‘Mount Washington in Winter’. The book does not feature any sightings or encounters with UFOs or anything of a paranormal nature.
That’s unsurprising, given that the object in the picture hails from an origin somewhat closer than other star systems - the object is actually a wooden ‘standard’ folding ruler. These were used on the featureless, snow covered terrain to help indicate the scale of the picture.
Errol Bruce-Knapp former UFO Radio Host and Moderator of the 18 year-old UFO UpDates List is not so sure:
“Specifically on the stereoscope that Ryan Mullahy dismisses I think his conclusion is flawed. I did a simple Solarize in an art program and the result clearly shows the object in front of the clouds/mountain... Further, makers of early images would have no awareness of what we now call UFOs. Of course I've been known to be wrong about many things...”
UFO expert Robert Moore is more in favour of a mundane explanation. He says:“It's common practice for scientific pictures to be shown with a scale. I think that's all it is, a ruler or similar on a pile of ice/snow to give an idea of scale. People posing in a picture does the same thing. Sometimes scales were inked in by people to give an indication of size, one arctic explorer even inked in a man with a sled team for the purposes of scale!”