The near-perfect cross was photographed by Mechaele Loraffe of Buchanan, Michigan, who could not resist pulling over to snap a gorgeous sunset as she drove to work. But it was only when she checked back at the picture that the amazing cross became apparent.
After she posted the shock snap on Facebook it went viral and has since ended up on various conspiracy, religious and even UFO websites.
Suggestions for what it was ranged from a sign from God before the rapture, an amazing trick of the light, and even proof of aliens.
Some people believed it was a sign from God.
One poster who saw the image in one of many YouTube videos now featuring it said: "What more do you need he has arisen and we will now see the second coming."
But another said: "Great picture, but that is just one of those things - a total fluke picture."
Scott C Waring, editor of UFO Sightings Daily, managed to involved aliens in the hypothesis.
He said: "This cross could be sign from aliens to a family nearby that really needed an answer to their prayers.
"Perhaps an alien overheard it since they do use telepathy and tried to calm them with a sign they would recognise."