Noctilucent Clouds: Every summer, something magical happens in the Irish night sky that most people have never heard of. Right now, as you read this, clouds made of ice crystals are forming at the very edge of space. And on a clear night, you can see them glowing blue-white from your back garden.
They are called noctilucent clouds, which is Latin for “night shining.” And June is the best time in Ireland to spot them.
Noctilucent Clouds: What exactly are they?
Ordinary clouds, the grey ones that block your sunshine on a Bank Holiday, float a few kilometres above the ground. Noctilucent clouds are nothing like those. They form roughly 80 kilometres up, in a layer of the atmosphere called the mesosphere. That is nearly ten times higher than a passenger plane flies, and right at the boundary where Earth’s atmosphere meets space.
Up there, temperatures drop to around minus 120 degrees Celsius, colder than anywhere on Earth’s surface. In those extreme conditions, tiny water vapour particles freeze around specks of dust, forming microscopic ice crystals. When enough of them gather together, they catch the light of the sun. Which, at that height is still shining long after it has set for us down on the ground, and they glow. Brilliantly. In shades of electric blue, silver, and white.
Noctilucent Clouds: Why can you see them in Ireland?
Ireland’s latitude is ideal. Noctilucent clouds are most visible between about 50 and 65 degrees north. And Ireland sits right in that sweet spot. The long summer evenings help too. Around the summer solstice (June 21st this year), the sun barely dips below the horizon, which means it can light up those high-altitude clouds for hours. Sightings have already been reported this season in Northern Ireland and across northwest Europe.
How do you spot them?
You do not need a telescope, binoculars, or any special equipment. Here is what to do:
Go outside between midnight and 2am on a clear night. Face north. Look low on the horizon. If noctilucent clouds are present, you will see a pale, rippling glow, often described as looking like blue-white waves or cobwebs shimmering in the dark. They move slowly, shaped by high-altitude winds that travel at around 400 kilometres per hour.
The key is darkness and a clear northern horizon. Get away from town lighting if you can, and give your eyes about 15 minutes to adjust.
Why right now?
The season runs from late May to mid-August, with June and July being the best months. This week, the season is in full swing. Sightings have already been confirmed in Northern Ireland and across northern Europe. The nights ahead, particularly around the summer solstice on June 21st,- offer some of the best viewing of the year.
So tonight, if the sky is clear, set an alarm for midnight, step outside, and look north. The edge of space is putting on a free show.
