You may recall that back in Blog-2006-06-24, I wrote about ghostly blue clouds that I observed in the northern sky at the end of my observing session. Well, as it turns out, I was fortunate enough to catch a glimpse of a type of cloud known as a Noctilucent_cloud. These extremely high altitude clouds are typically too faint to be seen. However, when illuminated from below by a deeply set sun, they are visible as the beautiful blue colour I observed.

So, how did I figure this out? Well, I happen to read the Astronomy Picture of the Day, and Today’s Feature Image just happened to be of noctilucent clouds.