This striking astronaut photograph shows polar mesospheric clouds over the Southern Hemisphere on January 30, 2010. These clouds occur over the high latitudes of both the Northern
and Southern Hemispheres during their respective summer months at very
high altitudes (approximately 76 to 85 kilometers, or 47 to 53 miles).
They are most visible during twilight, when the clouds are still
illuminated by the setting Sun, while the ground is already dark.
Polar mesospheric clouds are also known as noctilucent
or “night-shining” clouds—a property that is clearly visible in this
astronaut photograph. The clouds exhibit thin, wispy light blue forms
that contrast with the darkness of space (image upper right). Lower
levels of the clouds are more strongly illuminated by the Sun and
appear light orange to white. Clouds closest to the Earth’s surface are
reddish-orange (image center).
The image was taken approximately 38 minutes after midnight
Greenwich Mean Time (GMT), while the International Space Station was
located over the southern Atlantic Ocean. At this time of year, the Sun
never sets over Antarctica, but rather traces an arc across the local
horizon, allowing polar mesospheric clouds to be observed near local
The International Space Station (ISS) orbit ranges from 52 degrees
north to 52 degrees south; combined with the highly oblique
(“from-the-side”) views through the Earth’s atmosphere that are
possible with hand-held cameras, the ISS is an ideal platform for
documenting transient, high-altitude phenomena like polar mesospheric
clouds. Another NASA mission, the Aeronomy of Ice in the Mesosphere
is dedicated to the study of polar mesospheric clouds, and the
satellite is providing daily information about their formation,
distribution, and variability.
Astronaut photograph ISS022-E-52281
was acquired on January 30, 2010, with a Nikon D2Xs digital camera
fitted with a 70mm lens, and is provided by the ISS Crew Earth
Observations experiment and Image Science & Analysis Laboratory,
Johnson Space Center. The image was taken by the Expedition 22 crew. The image in this article has been cropped and enhanced to improve contrast. Lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab
to help astronauts take pictures of Earth that will be of the greatest
value to scientists and the public, and to make those images freely
available on the Internet. Additional images taken by astronauts and
cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by William L. Stefanov, NASA-JSC.