From the gaseous Ring Nebula now overhead to the beautiful Saturn system rising in the southeast, rings are a recurring celestial theme. Yet, nature lovers often miss the most spectacular examples, the bright beautiful halos that often encircle the moon and sun.
They may simply be too big to catch our attention. The standard halo has a 22-degree radius, closely matching an outstretched hand with thumb and little finger extended. But they're common. Halos appear against thin cirrus clouds several times each month, and are a time honored harbinger of bad weather. This ancient folklore has a sound basis, because the high icy clouds spawning halos often signal the approach of a warm front, with lowering and thickening layers a good bet a few hours later.
