I'm a newby to this site - but wondering if anyone knew what was going on with the moon tonight. There was an amazing circle around - at least a hands width span. It almost looked like an explosion - with Jupiter and Antares looking amazing as part of the picture ....
The halo is caused by ice crystals in the atmosphere. The halo is always at 22 degrees in width (of a full 360 deg in the sky) See here: http://www.atoptics.co.uk for a better explaination. I've seen a few, including some around the sun in the daytime, even here in Perth!