CREATE TABLE table_1559 ("No. in series" TEXT, "No. in season" TEXT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. viewers  ( millions ) " TEXT)

Name the original air date of 1/2 in season
SELECT "Original air date" FROM table_1559 WHERE "No. in season" = '1/2'
SELECT "Original air date" FROM "table_1559" WHERE "No. in season" = '1/2'