PRESS RELEASE ARCHIVES
NASA SATELLITE CAPTURES FIRST VIEW OF "NIGHT-SHINING"
WASHINGTON -- A NASA satellite has captured the first occurrence
this summer of mysterious iridescent polar clouds that form 50 miles above
The first observations of these clouds by the Aeronomy of
Ice in the Mesosphere (AIM) satellite occurred above 70 degrees north
on May 25. Observers on the ground began seeing the clouds on June 6 over
northern Europe. AIM is the first satellite mission dedicated to the study
of these unusual clouds.
These mystifying clouds are called Polar Mesospheric Clouds,
or PMCs, when they are viewed from space and referred to as "night-shining"
clouds, or noctilucent clouds, when viewed by observers on Earth. The
clouds form during the Northern Hemisphere's summer season that begins
in mid-May and extends through the end of August. They are being seen
by AIM's instruments more frequently as the season progresses. The clouds
also are seen in the high latitudes of the Southern Hemisphere during
the summer months.
Very little is known about how these clouds form over the
poles, why they are being seen more frequently and at lower latitudes
than ever before, or why they have been growing brighter. AIM will observe
two complete polar mesospheric cloud seasons over both poles, documenting
for the first time the entire, complex life cycle of PMCs.
"It is clear that PMCs are changing, a sign that a
distant and rarified part of our atmosphere is being altered, and we do
not understand how, why or what it means," stated AIM principal investigator
James Russell III, Hampton University, Hampton, Va. "These observations
suggest a connection with global change in the lower atmosphere and could
represent an early warning that our Earth's environment is being altered."
The AIM instruments are returning valuable information on
the global extent and variability of these clouds and preliminary information
on their particle sizes and shapes. Early indications are that the clouds
occur at high latitudes early in the season then move to lower latitudes
as time progresses. The AIM science team is studying these new data to
understand whether the changes in the clouds may be related to global
When the Northern Hemisphere summer season ends in mid-
to late August, the AIM science team will not have to wait long before
the Southern Hemisphere's season starts. This occurs about three months
later in mid- to late November. The Southern season lasts until approximately
mid-March of 2008. Early results from the AIM mission will be reported
at a major international conference focused on PMCs and other high altitude
layered phenomena to be held at the end of August 2007 in Fairbanks, Alaska.
The satellite was launched on April 25, only four weeks
before the first science observations began. During the satellite-commissioning
phase and now in routine observations, all three state-of-the-art instruments
have been working exceptionally well and returning high quality data.
The Cloud Imaging and Particle Size instrument offers a
2-D look at the clouds, collecting multiple views from different angles.
The cameras are providing panoramic PMC images of the Arctic polar cap
daily. The Solar Occultation For Ice Experiment is measuring new information
on cloud particles: their variability with altitude, the chemicals within
the clouds and the environment in which the clouds form. The Cosmic Dust
Experiment is recording the amount of space dust that enters Earth's atmosphere
to help scientists assess the role this dust plays in PMC formation.
The AIM mission coincides with the two-year, worldwide scientific
community's International Polar Year, and the mission is expected to make
unique contributions to the International Polar Year's objective of advancing
AIM is the ninth Small Explorers mission under NASA's Explorer
Program and is managed by the Explorers Program Office at the Goddard
Space Flight Center, Greenbelt, Md. The AIM Project Data Center is located
at Hampton University.
For related images on this story, please visit:
Dwayne Brown/Tabatha Thompson
Headquarters, Washington June 28, 2007
Goddard Space Flight Center, Md.
Hampton University,Hampton, Va.