Yesterday there was an especially great display of noctilucent clouds to see over the horizon in northern Europe. After the sunset the sun illuminates ice particles that formed because of meteorite smoke trails in the very upper layer of the atmosphere - spaceweather.com is great at explaining it into more detail. But the phenomenon is not yet fully understood (why it can be seen lower in the south in recent years for example), which makes it even more interesting

Fascinating.

[nocturnal]

I woke up at 2.30am a few days ago, went out the back and I was astounded at the noctilucent clouds to the East over the city. Unfortunately my camera gear was in another house :-(

These clouds are at their peak now and especially this year and in my view as beautiful as the aurora.

[slowpez]

You learn something new everyday. Those clouds are beautiful.