Clouds That Shine at Night

Noctilucent clouds are tenuous ice formations in the upper atmosphere. From the ground, they appear only during astronomical twilight.

These ice crystals exist 76 to 85 km above Earth. The mesosphere keeps its water budget tight.

Ice grains need temperatures below about minus one hundred twenty degrees Celsius to form. Summer upwelling makes the mesosphere coldest then.

Otto Jesse photographed noctilucent clouds first in 1887. He had studied Krakatoa sunsets the previous year.

Noctilucent clouds were first detected from space.

The AIM satellite launched on 25 April 2007. Dedicated images revealed shapes resembling ordinary tropospheric clouds.

Mars Express found carbon dioxide crystal clouds reaching 100 km above Mars. These remain the highest clouds over any rocky planet.

A suborbital rocket released water canisters over Alaska on 26 January 2018.