Residents in the Australian town of Mildura were left puzzled on Wednesday after the evening sky was filled with a strange pink glow.
Photos posted to social media show how the dim, cloudy sky was illuminated with a bright pink circle. There also appeared to be a cone of light directed upwards from the ground, suggesting that the pink light had a ground-based source.
The phenomenon sparked jokes from a couple of observers, including references to aliens or the popular paranormal drama series Stranger Things. One observer called the light "scary but brilliant."
Hey @JaneBunn any reports of this scary but brilliant sky over Mildura tonight ?? pic.twitter.com/3WZ7FZj1zp
However, it wasn't long before residents had an answer: The pink glow was coming from a nearby cannabis farm.
Peter Crock, CEO of the Cann Group medicinal cannabis company, told local news outlet ABC Mildura-Swan Hill that the pink glow was caused by the farm's grow lights, which run on a 12-hour cycle from 7 a.m. to 7 p.m.
"Normally, the blackout blinds close at the same time as the sun sets, but last night we had the lights on and the blinds hadn't yet closed, so there was a period where it created a glow," he said, adding that the glow was a one-off event.
Asked if the glow had caused any attention, Crock said that overnight security staff did report "some activity," but further details weren't reported.
Online marijuana resource American Marijuana calls grow lights "the first step to a successful indoor harvest" and notes that there are several different types of LED grow lights that farmers might use.
The reason that grow lights are needed is because cannabis plants are just like any other in that they require energy from light to carry out photosynthesis.
"A red spectrum light is often used," Rhys Cohen, Cann Group's senior communications manager, told The Guardian. "Normally the facility would have blackout blinds that come down at night, and will in the future block that glow."
Cann Group announced it was harvesting its first commercial medical crop at its Mildura facility in June after a cultivation permit was issued by the Office of Drug Control in March, Cannabiz reported.
Medical cannabis is heavily regulated in Australia, but it's generally legally available if prescribed by a doctor, according to the University of Sydney. The doctor would need approval from the Therapeutic Goods Administration as well as the local government.
Medical cannabis is being investigated as a treatment for many different diseases including epilepsy and multiple sclerosis, as well as a treatment for chemotherapy side-effects, according to Australian health site Health Direct.
The recreational version is still illegal in most states and territories in Australia.
Update 7/21/22, 5:06 a.m. ET: This article has been updated to include a new image and a quote from Peter Crock.
Join half a million readers enjoying Newsweek's free newsletters