To welcome the shortest day of the year, the National Aeronautics and Space Administration (NASA) released a stunning image of solar ice halos.
The photo taken at lunchtime on Dec. 14 shows light from at least three halo rings shining across an icy river near Utendal, Sweden. NASA said on its website it is “extremely rare” to see anything like this complex of halos in this “astounding scene”.
The image has a 22-degree halo, sundogs (parhelia), and sun pillars. According to NASA, the patterns appear when sunlight (or moonlight) reflects and refracts in six-sided water ice crystals in the air that are also commonly called diamond dust. The ice crystals reflect and refract light just as mirrors would, sometimes splitting the light into different colors.
“In this case, likely local contributors to the atmospheric ice crystals are snow making machines operating at a nearby ski center,” NASA said on its website. “The extensive array of rarer halos has been identified along with previously unknown features.”
Simple ice halos, which are more common than rainbows, can be easily seen by the naked eye when shaded from direct sunlight.
The word halo originates from the Greek term halōs, which appear in different forms that vary in color and shape. Some can be white rings while others can be spots that appear in the sky. They can mostly be seen near the sun or moon.
Since the dawn of civilization, humankind has tracked the movement of the sun and Great Britain’s Stonehenge monument was built about 5000 years ago for this very purpose. If one watches the sunrise in June, on the longest day of the year, sunlight appears behind one of the main stones, giving the illusion of the sun balancing on the stone.
— English Heritage (@EnglishHeritage) December 22, 2018
The December Solstice (Dec. 21) is called the first day of winter in the northern hemisphere and summer in the south. The phenomenon occurs because the sun is at its most southerly position.
This year’s solstice was significant due to the full moon or “Cold Moon” appearance in the night sky along with the Ursid meteor shower, which is called that because the meteors seem to come from the Ursa Minor, more commonly known as the Little Dipper star constellation.
The solstice also provided the illusion of the planets Mercury and Jupiter seeming like they were about the collide in space, with just a 0.9 degree distance (or two moon diameters).
By Richard Szabo