From 19-21 February 2013, noctilucent clouds were observed in the UK, Denmark, Norway and the Netherlands. Since these clouds are usually only seen in summer, it is suspected that they may be the result of comet dust deposited in the upper atmosphere by the Chelyabinsk/Chebarkul meteor or comet fragment explosion over Southern Russia on 15 February.

The following images were submitted to spaceweather.com
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© Terry ParkerImage taken by Terry Parker on Feb. 20, 2013 from above Birmingham, UK. 'I am an airline pilot in the UK and I occasionally see noctilucent clouds. Usually during the summer at about midnight looking North. But yesterday (20 Feb 13) I was very surprised to see them looking south towards France and so close to sunrise.'

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© Tom AxelsenPhoto by Tom Axelsen, Copenhagen area, Denmark

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© Henrik BondoPhoto by Henrik Bondo, Denmark

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© Jan TrompTaken by Jan Tromp on February 21, 2013 @ Beverwijk, Netherlands

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© Margaret HughesTaken by Margaret Hughes on February 19, 2013 @ Askam-in-Furness, Cumbria, England.