Look up an hour or two after sunset and before sunrise over the subsequent few months and you might see ethereal blue, silver or golden streaks within the Northern Hemisphere’s northern skies.
Called noctilucent clouds (meaning “night-shining” clouds in Latin)) or NLCs, these strange-looking patterns within the sky are the best, driest, coldest and rarest clouds on Earth, in response to a 2018 study of the phenomenon.
These shimmering, night-shining clouds appear within the mesosphere — a layer of Earth’s atmosphere above the stratosphere and below the thermosphere, about 47 to 53 miles (76 to 85 kilometers) above Earth’s surface. Sometimes dubbed “space clouds,” NLCs form slightly below the invisible boundary where Earth’s atmosphere ends and outer space begins, roughly 62 miles (100 km) above the planet’s surface, in response to NASA.
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NLCs occur when water vapor freezes into ice crystals that cling to dust and particles left by falling meteors high within the atmosphere, which reflect sunlight. The height season for observing NLCs from the Northern Hemisphere is across the summer solstice in late June through the tip of July, once they’re most easily visible from about 50 to 70 degrees north latitude, in response to Windy. Nonetheless, some NLCs have already been spotted this month in colder, northern regions like Denmark, in response to Spaceweather.com.
NLC sightings were at a 15-year high last summer, in response to the Washington Post. Sightings have grow to be more frequent in recent times and at lower latitudes, possibly because climate change generates more water vapor within the atmosphere consequently of increased atmospheric methane, in response to NOAA.
For the most effective probability to see some NLCs within the evening, you’ll have a great view low to the northern horizon as the celebrities begin to shine in late twilight. It’s typical to see displays in the underside 20 to 25 degrees of the northern sky, in response to Sky & Telescope. Naked eye viewing is the most effective option to find noctilucent clouds, but with a pair of the best binoculars for stargazing, you may get a wonderful close-up of the structure of one in every of the summer’s most elusive and impressive sky sights.