In June and July, turn your head to the north as the stars come out for a
chance to observe the extremely uncommon noctilucent clouds, often known as
"night-shining" clouds.
Over the next several months, look up an hour or two after sunset and
before sunrise to observe ethereal blue, silver, or golden streaks in the
northern sky of the Northern Hemisphere.
According to a
2018 study
of the phenomena, these strange-looking patterns in the sky are known as
noctilucent clouds (abbreviated NLCs), which means "night-shining" clouds in
Latin.
About 47 to 53 miles (76 to 85 kilometers) above Earth's surface, in the
mesosphere, a region of the atmosphere above the stratosphere and under the
thermosphere, are these shimmering, night-shining clouds. NLCs, often called
"space clouds," are thought to develop around 62 miles (100 km) above the
surface of the planet, just below the invisible line that separates Earth's
atmosphere from space.
NLCs develop when water vapor condenses into ice crystals that stick to
meteor debris and dust high in the sky, reflecting sunlight. According to
Windy, the best time to observe NLCs from the Northern Hemisphere is late June
through the end of July, around the time of the summer solstice, when they
are easiest to see from 50 to 70 degrees north latitude. However, according
to Spaceweather.com, some NLCs have
already been seen this month in colder, northern locales like Denmark.
The Washington Post
reports that last summer saw a 15-year peak in NLC sightings. According to
NOAA, sightings have risen recently particularly at lower latitudes, presumably
because climate change causes more water vapor to be produced in the
atmosphere due to an increase in atmospheric methane.
You'll need a clear view low to the northern horizon as the stars start to
come out in the late twilight hours if you want to have the best chance of
seeing several NLCs in the evening. According to
Sky & Telescope, displays are often visible in the lower 20 to 25 degrees of the northern
sky. The best method to see noctilucent clouds is with your naked eye, but
using the best stargazing binoculars will give you an incredible up-close
glimpse of one of the summer's most elusive and magnificent sky views.
