Winter cold brings sun dogs, moon dogs and light pillars in MN skies

The skies can be most alluring in winter. Besides sharper, low-moisture nights for star-gazing and possible northern lights, you might catch sight of moon dogs, sun dogs and ice pillars.

Sun dogs appear when there are enough hexagonal plate-shaped ice crystals in the atmosphere to refract sunlight. They can look like rainbow parentheses (red on the inside and blue violet on the outside) or they can look like a halo that seems to fully encircle the sun, according to the National Weather Service.

The optical effect can also be seen at night when moonlight reflects off atmospheric ice crystals. As with the sun, moon dogs appear about 22 degrees to the left and right of the full- or almost-full moon and often appear when thin veils of cirrus clouds linger in the atmosphere.

The special effects are sometimes called mock suns and are officially known as “parhelia,” Greek for “with the sun.” Theories for how “dogs” became the common description range from myths about the Greek god Zeus walking his dogs across the sky to Norse mythology. The reflections can look like companions faithfully flanking their owner.

Light pillars, which look like vertical spotlights beaming toward space, can be seen when light from earth illuminates ice crystals above it. Pillars may also be seen at dawn or dusk when the rising or setting sun refracts through ice crystals.

No matter how they glow, these phenomena offer celestial ways to appreciate the whims of winter weather.

Lisa Meyers McClintick has freelanced for the Minnesota Star Tribune since 2001 and volunteers as a Minnesota Master Naturalist.