"The air was very cold and filled with small ice crystals on Dec. 28th when we saw these strange pillars of light," reports Aigar Truhin of Sigulda, Latvia. "My son exclaimed, The aliens are coming!" It certainly looked that way." Truhin snapped this picture using his Nikon D90:

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© Aigar TruhinPhoto details: Nikon D90, 5 sec. exposure @ ISO 200-640

Many people have seen light pillars. They appear during winter when city lights shine upward into the icy air. Reflections from plate-shaped crystals spread the light into a vertical column: examples.

Truhin's pillars, however, are not the ordinary kind. Even two leading experts in atmospheric optics can't quite figure them out: "These pillars are mysterious," say Les Cowley and Marko Riikonen. "They have unexplained curved tops and even curved arcs coming from their base. Arcs in rare displays like these could be from column crystals to give parts of tangent arcs, others could be the enigmatic Moilanan arc or even the recently discovered reflected Parry arc. We do not know - so take more photos on cold nights!"