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This phenomenon seems to be flourishing during solar minimum.

June 23, 2020: On June 21st, something rare and magical happened in London. The skies of the great city filled with noctilucent clouds (NLCs). Phil Halper noticed the display, grabbed a camera, and raced from one landmark to another, hurriedly recording pictures like this:

“Even the bright lights of the London Eye on the river Thames couldn’t drown out the display,” says Halper. “These were the most spectacular NLCs I’ve ever seen.”

If NLCs look alien–that’s because they are. The clouds are seeded by meteoroids. They form every year around this time when summertime wisps of water vapor rise up to the mesosphere, allowing water to crystallize around specks of meteor smoke.

Usually you have to be under a dark sky at high latitudes to see these rare clouds–but 2020 is not usual. Record-cold temperatures in the mesosphere are boosting NLCs, brightening them enough to see from places…