Starwatch: noctilucent clouds are a huge summer spectacle – Guardian

It is the week of the summer solstice in the northern hemisphere. The longest day of the northern three hundred and sixty five days falls on 20 June and by big traditions, this marks the muse of summer.

In the southern hemisphere, this is the wintry climate solstice, marked by the longest evening.

Whereas such long days lower down the hours for ancient stargazing, other targets offer their very have outlandish spectacles. Early summer is big for sighting noctilucent clouds (NLCs). They’ll appear about 30 minutes after sundown in the west. This week, from London, the solar objects at about 21.20 BST.

NLCs are the very best known clouds that originate in Earth’s ambiance, present at an altitude of about 50 miles (80km). They’re conception to be in actual fact pure phenomena made of ice crystals, even if how the water molecules attain so high in the ambiance is a mystery.

The clouds appear as excellent-making an try white or faded blue streaks all over a shadowy sky. They eye somewhat like cirrus clouds but can even be celebrated because cirrus clouds put not glow and so are visible most sharp in the daylight. NLCs manufacture an even making an try, if eerie watch, shining brightly in opposition to the darkness of the evening sky.