If you've seen a purple sky in Charlottetown recently, don't panic. It's been there for quite a while, says the owner of a cannabis-growing operation whose greenhouses use a particular type of lighting.
Alex Smith, the chief executive officer of FIGR East, said the effect of a purple sky is caused by LED lights his company uses to grow marijuana.
The lights operate from 6 a.m. AT to 6 p.m. all year, and are only noticeable during winter months, when there is less daylight.
"When the days are shorter, you see our LED lighting popping up and we use a red, white and blue spectrum for our lights," he told CBC News. "They combine and make that kind of purple hue that you see a little bit in the nighttime this time of year."
On a clear night, the reflection in the sky can be seen from far away.
Smith said he just recently noticed the lights himself, when he was at his home in Sherwood.
"Somebody had made a comment to me that they could see it. I just walked over to the end of my driveway and looked over, and sure enough I could see the lights popping up all over the skyline," he said.
Neither aliens nor northern lights
CBC meteorologist Jay Scotland said that while the colour of the sky is largely determined by atmospheric conditions and the position of the sun, the combination of those two factors is unlikely to cause the purple light.
"While it is possible for a purple hue to have a natural cause, it would be quite rare," he said. "In this case, we know that weather is not responsible. That being said, a layer of low cloud may help to reflect or carry that purple light over a larger area on some nights."
While the LEDs are a perfectly reasonable explanation, Smith said he has been amused to hear speculation about what causes the purple sky.
"We do certainly get a kick out of some of them, whether it's aliens or northern lights or something else, but honestly the feedback that we get is pretty positive for the most part," he said.
The purple sky does not result from a chemical reaction, Smith said. It is simply a reflection of a mix of colours.
"There's nothing harmful about it, it's literally just a light reflection. That can put people's minds at ease if that is a concern," he said.