The moon was casting a rainbow through the spray from the waterfall.

月亮在瀑布溅起的水雾中映出了一道彩虹。

《柯林斯英汉双解大词典》

"A moonbow is just like a rainbow but is caused by the moon reflecting off rain mist at a certain Angle," says Pacholka.

一道月虹就像一道彩虹，它是由月光在湿度大的薄雾中经过一定角度反射形成的。

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In the case of the rainbow, sunlight produces its effect directly. In the case of the moonbow, however, that sunlight is first reflected off the surface of the moon and then shines back down to Earth.

彩虹是在阳光直射下产生；而产生月虹时的阳光是由月球表面反射到地球的。

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Vasco travels over the ocean and over the rainbow, where he meets Judy Garland and the Tinman, to say nothing of Miss Universe perched on the moon in a gorgeous light (the part was gorgeously sung by Janice Felty).

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