moonbow
noun [ C ] uk/ˈmuːn.bəʊ/ us/ˈmuːn.boʊ/ (also lunar rainbow, /ˌluː.nə ˈreɪn.bəʊ/ /ˌluː.nɚ ˈreɪn.boʊ/)
月虹（月光形成的虹，呈银色）
an arch (= curved shape) of white light seen in the sky when rain is falling and the moon is shining
Compare: rainbow