We're now well into June, so please, PLEASE keep your eyes open for displays of noctilucent clouds - "NLC" - on any clear nights between now and the end of July.

Noctilucent clouds are clouds of icy dust that only form in summer, in the very highest reaches of the atmosphere, when conditions are just right.

We don't see them at any other time if year, and can't predict with any real accuracy when they will appear - all we can do is look to the north after 11:30pm on any clear nights and hope to see them.

Unlike "normal" water vapour clouds which appear as dark patches silhouetted against the bright summer sky, NLC appear as bright silvery white or even electric blue streamers and ribbons, often behind any dark clouds that might be visible.

A really good display of NLC can last from sunset to sunrise, filling the sky with beautiful billows, whirls and swirls of light that look like an energy field from a big budget science fiction film.

The most vivid displays can be bright enough to cast shadows.

You don't need any equipment to see NLC, they are clearly visible to the naked eye.

However, of you have a pair of binoculars you should definitely take them with you if you go out on an NLC hunt, as they will show you lovely fine detail and structure within the clouds that our eyes can't pick up.

By the time you read this there should already have been a few good displays, perhaps even a major one.

But there will be many more to come before the NLC season ends at the start of August. so good luck.