Day and night are as cool as water. Which of our traditional festivals does it refer to?

Hello! The poem comes from Du Mu's Autumn Night, and the next one is "Sit and watch the morning glory and weave the stars." It is related to the traditional festival Begging for Skills Festival in China. The whole poem is as follows: Qiu Guang drew a cold screen with a silver candle, fanning a small fan and pouncing on fireflies. Day and night are as cool as water. Sit and watch the morning glory and Vega. This is about the loneliness and bitterness of a frustrated girl's life. The first sentence is about autumn scenery, and the word "cold" is used, which implies the crisp atmosphere in autumn and shows the inner loneliness of the hero. Write two sentences to kill time and relieve depression by flapping fireflies. Three words: I can't sleep at night, waiting for good luck, taking the street as water to compare your love as ice. In the last sentence, I admire the Cowherd and the Weaver Girl to express my grief. Heng Tang retired and commented: "Layers of scenery are a painted figure painting. Just the word' lying down and watching' will make you feel smart. " Thanks for reading!