Venus Pillar -
Imaged by John Gauvreau through an 80mm refractor at Hamilton, Ontario, Canada. ©John Gauvreau, shown with permission.
Pillars are not upward and downward beams of light. They are instead the glints of light reflected towards the eye from millions of ice crystals in high cloud or haze.
Usually a bright light like the sun or moon is needed to make the pillar visible. Here, the planet Venus is sufficiently bright to produce a small one.
Unlike most other ice halos, those making pillars are not precisely aligned - they actually need to be wobbly and have fairly large tilts from horizontal. Nor is crystal perfection needed. Crystals approaching snowflake in size and complexity can produce them.
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