CREATE TABLE table_73580 ("No. in Series" FLOAT, "No. in Season" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "U.S. viewers  ( millions ) " TEXT)

When did the episode viewed by 10.50 millions of people in the US run for the first time?
SELECT "Original air date" FROM table_73580 WHERE "U.S. viewers (millions)" = '10.50'
SELECT "Original air date" FROM "table_73580" WHERE "U.S. viewers (millions)" = '10.50'