BALTIMORE — A Nasa satellite mission will be launched this year to study the highest and most mysterious clouds on Earth. Noctilucent, or ‘night-shining’, clouds appear as thin bands in twilight skies, some 80km (50miles) above the surface. Recent records suggest they have become brighter, more frequent and are being seen at lower latitudes than usual. Scientists cannot say for sure but they suspect human activity may be altering the conditions in the mesosphere that drive the clouds’ formation. ‘Noctilucent clouds were first seen in 1885 by a British amateur astronomer, Robert Leslie,’ explains James Russell from Hampton University, Virginia, US. The changes in frequency and brightness have been observed over the past 20 years Normally confined closer to the poles, they have been seen as low as 50 degree North ‘They’re very beautiful. They have distinctive features – bands, and ripples we call billows – and form right on the edge of space.’ Russell is the principal investigator on the AIM (Aeronomy of Ice in the Mesosphere) spacecraft, which will be lofted to 600km (370 miles) to make a detailed study of the clouds. The 195kg (430lb) satellite will be put […]

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