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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

A photograph of noctilucent clouds and their reflection.
Above: Noctilucent clouds photographed by Pekka Parviainen.

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

A photograph of noctilucent clouds over Utah, U.S.A.
Above: A PMC is observed and
photographed at 40 degrees latitude
for the first time! Photo by AIM
Co-Investigator Dr. Michael Taylor.

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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NASA Fact Sheet

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Objectives and 2011 Report

AIM and YouTube Videos
Library: Video
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Science at NASA
AIM Mission

STS-119 NLC Cloud
Space Shuttle Created NLC

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NASA Aeronomy of Ice in the Mesosphere

More on the Web

Laboratory for Atmospheric and Space Physics, University of Colorado (2015) Aeronomy of Ice in the Mesosphere—CIPS Instrument. (2015) Realtime NLC Gallery.

NASA Earth Observatory (2013, June 25) Early Start for Noctilucent Clouds.

NASA Earth Observatory (2011, January 27) Night-Shining Clouds Are Getting Brighter.

Space Weather News

Strange Clouds
Astronauts onboard the International Space Station have been observing electric blue "noctilucent" clouds from Earth-orbit.

A view of noctilucent clouds from the International Space Station.

Above: Electric blue clouds viewed from the ISS. Photo credit: Don Pettit and NASA TV.

Mysterious Summer Clouds of the Night

NASA's Sun-Earth Education Forum Logo

The AIM mission is a part of
NASA's Sun-Earth Connection Education Forum.

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