Beautiful visions in winter sky are due to perfect mix of light and ice, experts say

Mark Price
·2 min read

The list of things occasionally mistaken for UFOs is long, but among the oddest is a series of winter phenomena with odd names like sundogs, halos and sun pillars.

Examples began showing up this weekend on Facebook, after 8 inches of snow fell on parts of the North Carolina mountains.

Grandfather Mountain, a park in the N.C. mountains, shared multiple photos of rainbow-type formations circling the sun in an otherwise clear sky, and similar mirages were seen in Boone and Banner Elk, Facebook posts show.

It’s coincidental that the photos appeared just days after the U.S. Fish and Wildlife Service addressed the topic with a photo of its own, showing bars of light on either side of the sun.

“Have you ever noticed these bright spots, sometimes accompanied by a rainbow, on each side of the sun?” the agency wrote Jan. 8.

“This phenomenon is known as a sundog and is caused by light refracting off ice crystals in the atmosphere.”

Sundogs may look a bit like rainbows, but they fall into the same category as similar atmospheric oddities known halos and sun pillars, the National Weather Service says. All are ”optical effects” created when “water drops and ice crystals can act as a prism, allowing us to see the various colors that make up visible light,” the NWS reports.

While the U.S Fish and Wildlife Service posted a sundog, the image at Grandfather Mountain was more of a halo.

Here are the differences, according to the National Weather Service:

  • Sundogs, also known as mock suns or parhelia, appear as “colored spots of light” at 22 degrees on either side or both sides of the sun, “depending on where the ice crystals are present.”

  • Halos are white rings “around the sun or moon as the sun or moon light refracts off ice crystals present in a thin veil of cirrus clouds.”

  • Sun pillars resemble shafts of light “extending vertically above the sun,” usually before dawn or dusk. “They develop as a result of ice crystals slowly falling through the air, reflecting the sun’s rays off of them.”

The Computer UFO Network, Sky & Telescope and other science sites report all three visual occurrences are part of a long series of “atmospheric phenomena” frequently mistaken for UFOs.