A Striking Lunar Halo

A full 360-degree ring around the moon Saturday night. This was a classic 22-degree halo, created by light bent by millions of microscopic, hexagonal ice crystals in cirrostratus clouds.  Details: 16mm lens at f/2.8, 2.5 second exposure at ISO 200. Photos: Bob King

An odd, oval glow around the planet Venus last night caused by high clouds. Was it a Venus corona? Details: 200mm lens at f/2.8, 2-second exposure at ISO 800.

I hope you got to see the huge halo around the full moon last night. It lasted for hours. Clouds threatened early (right) but the moon prevailed. After making a few photos of the scene, I put on skis and enjoyed a run down the trail. Around 9:30, it looked like the halo might fade away, but a half hour later around it reformed. Even Venus was surrounded by an odd oval glow. While the stretchy shape was faintly visible with the eye, it showed up better in the camera. What exactly was this glow around the planet? I’m guessing it was a little corona, similar to the ones we sometimes see around the moon.

Amateur astronomer Jim Schaff of Hermantown has been patiently recording the changing size of the moon as it orbits the Earth. Schaff created this wonderful comparison panel showing the full moon in May 2008 at apogee (furthest from the Earth) and near perigee (closest to Earth) two nights ago. Seeing the two moons side by side illustrates the size difference very effectively.

"The full moon has its own beauty," said Schaff, "even if it blocks the view of most other astronomical sights."