If you’ve looked up at the sky just after sunset over the last few days, you may have spotted a stunning display of unusual glow-in-the-dark clouds.

These extremely rare ‘noctilucent clouds’ are currently appearing over much of the northern hemisphere.

In fact, they’ve put on their most intense display for 15 years, according to data from Nasa.

Skywatchers across the UK have been seeing them everywhere from Yorkshire to Wales to Dundee.

And they’ve been flooding social media with pictures of the beautiful bluish and silvery streaks in the sky.

In the early hours of Tuesday morning, Queen legend and astronomer Brian May shared his own video of the clouds on Twitter and Instagram.

Noctilucent clouds, which tend to appear in clear summer skies, are only visible from countries that sit within between 45 and 80 degrees north latitude, according to the Met Office.

They form at equivalent latitudes in the southern hemisphere as well, but there’s hardly any land to watch them from in this region. Down south, you can only see them at the southern tip of Argentina and Chile, as well as the Antarctic.

But in the northern hemisphere, they’ve been spotted everywhere from Seattle in the US to Szubin in Poland over the last couple of days.

What are noctilucent clouds?

Noctilucent clouds are collections of ice crystals that linger high up in the mesosphere: a section of the atmosphere sometimes referred to as ‘the edge of space’.

Because they’re so high, they can still reflect sunlight after sunset and before sunrise. This means they can glow brightly against they dark evening sky.

They form when water vapour and dust gather in the very cold mesosphere. They’re so rare because this material is in short supply in this region of the sky.

Some of the dust that collects so high up may come from tiny meteors, the Met Office states. But it’s likely much of it has less exotic origins, like volcanoes and even man-made pollutants.

NASA’s AIM satellite is studying the clouds to find out more about how they form and whether they’re linked to climate change.

As you can see from the chart below, AIM data shows this most recent display has been particularly intense.

A SUDDEN INCREASE IN NOCTILUCENT CLOUDS: NASA’s AIM spacecraft has just detected a surge in noctilucent cloud (NLC) activity–the biggest spike in 15 years. If this continues, NLCs could be easy to see over the long 4th of July weekend. https://t.co/IcDkOot3K6 has the details. pic.twitter.com/mSOfyTDvrh

Atmospheric physicist Cora Randall from the University of Colorado Boulder, who works with AIM data, says this particular spike might be linked not to climate change, but to space rockets.

She told Spaceweather.com: ‘We’re speculating that the spike might be due to extra water vapor transported to higher latitudes from rocket launches. But much more quantitative analysis would be required to confirm that or not.’

Source: Read Full Article