הַשֶּׁ֙מֶשׁ֙ יֵהָפֵ֣ךְ לְחֹ֔שֶׁךְ וְהַיָּרֵ֖חַ לְדָ֑ם לִפְנֵ֗י בּ֚וֹא י֣וֹם יְהוָ֔ה הַגָּד֖וֹל וְהַנּוֹרָֽא׃
The sun shall be turned into darkness, And the moon into blood, Before the great and terrible day of the LORD come.
Rashi on Joel
shall turn to darkness—to embarrass those who prostrate themselves to the sun.