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AstroCappella: Noctilucent Cloud

The AIM Mission

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noctilucent clouds The Aeronomy of Ice in the Mesosphere (AIM) mission is the first detailed exploration of Earth's unique and elusive clouds that are literally on the "edge of space." Other space-based and ground-based measurements have probed some aspects of this unusual phenomenon in Earth's mesosphere (the region just above the stratosphere), but very little is known about how these clouds form over the poles, why they are being seen at lower latitudes than ever before, or why they have been growing brighter and more frequent. Some scientists have suggested that these polar mesospheric clouds may be the direct result of human-induced climate change.

AIM in the cleanroom Over the course of its two-year mission, AIM will help answer these questions by documenting for the first time the entire complex life cycle of these clouds. With this information, scientists will be able to resolve many of the mysteries about how these clouds form and be better able to predict how they will change in the future.

AIM was successfully launched on April 25, 2007.

Observing Tips


Look west 30 to 60 minutes after sunset when the Sun has dipped 6 to 16 degrees below the horizon. If you see luminous blue-white tendrils spreading across the sky, you've probably spotted a noctilucent cloud. Although noctilucent clouds appear most often at high latitudes such as Scandinavia and Canada, they have been sighted in recent years as far south as Colorado, Utah and Virginia. NLCs are seasonal, appearing most often in late spring and summer. In the northern hemisphere, the best time to look would be between mid-May and the end of August.

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