Moonlight
Moonbeam
noun
The moon light (not sunlight!) can be bright sometimes. This is night when you're stumbling home from a nomikai after work. What is this light from the moon called? It's moon light. This word can also mean a moonbeam as well.
げっこう
The reading is the on'yomi readings put together, though 月 is modified and shortened a bit. げつ goes to げっ. Make note of the different sized つ otherwise you'll be confused why you keep getting this one wrong over and over again!
そのよるは、月光がとてもきれいでした。
The moonlight was very beautiful that night.
一りんの白い花に、月光がさえざえとふりそそいでいた。
The bright moonlight was beaming down onto a white flower.
月光に照らされた彼女は、とても美しかった。
She looked so beautiful in the moonlight.