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SCIENCE
MISSION SUMMARY - 1
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The Aeronomy of
Ice in the Mesosphere, or “AIM”, experiment is a NASA
space mission designed to study the highest clouds in the Earth’s
atmosphere – clouds at the edge of space. These
clouds are made of frozen water, or ice crystals, just like some
of the clouds that appear in the sky every day. Unlike more common
clouds that form up to 5 miles above the surface of the Earth, these
clouds are 50 miles high in a layer of the atmosphere called the
mesosphere. Also unlike normal clouds, these clouds can only be
seen near twilight, when the sun is just below the horizon and the
sky is |
Above: Noctilucent clouds photographed by
Pekka Parviainen.
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dark. For this reason, they are often called “noctilucent”
clouds, or NLCs, because the word noctilucent means “night-shining”.
Scientists also call these clouds “polar mesospheric clouds”,
or PMCs for short, because they usually form only at high latitudes
near the north and south poles. In recent years, however, several people
have reported seeing NLCs at lower latitudes,
even as low as 40°N
Above: A PMC is observed and
photographed at 40 degrees latitude
for the first time! Photo by AIM
Co-Investigator Dr. Michael Taylor.
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in
the continental United States, in Utah and Colorado. Also, NLCs seem
to be getting brighter over time. Scientists do not understand why
this is happening, and would like to find out. In particular, they
wish to determine if these changes are caused by natural variations
in the Earth’s atmosphere, or if they are influenced by human
activities. |
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