Light echoes are reflections of light from distant objects in space. But what do they look like and how can they best be seen? Sir Patrick Moore and his guests Professor Mike Bode and Dr Tim O'Brien explain all.
Chris Lintott helps to construct a new radio telescope in Hampshire while Pete Lawrence and Paul Abel preview what is on view in the October skies.
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Ready to Watch The Sky At Night, Season 2010, Episode 10?