'Blue moon' appears for a second time in 2018
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Photo taken on Saturday, March 31, 2018 shows the blue moon above West Lake in Hangzhou, in east China's Zhejiang Province.A 'blue moon' appeared for the second time this year on Saturday, March 31, 2018. A blue moon is means a second full moon within one a calendar month, which is quite rare. The next blue moon is due in October 2020. [Photo: IC]