photo #6124974

Concentric rings of colour known as a corona can appear around the Sun or Moon as its light shines through thin cloud and is diffracted around the tiny droplets or ice crystals. The corona is most apparent when the cloud is a continuous layer, when it appears as an unbroken bluish-white circle, often surrounded by colourful rings. But as Lyndy Belchere (Member 61,208) discovered, coronas can also appear in broken clouds like these Altocumulus she spotted over Santa Barbara, California, US. Fragments of a corona appeared only where droplets in the Altocumulus cloudlets were near to the position of the Sun. You have to look closely to spot them – which, by the way, is something you should never do! It is possible to damage your vision without even realising if you look directly at a bright Sun. When observing coronas and other optical phenomena caused by thin cloud, be sure to cover the Sun with an object like your hand to protect your eyes. Better still, take a photograph and check that – before sending it in like Lyndy did so others too can enjoy it with undamaged eyes.