CREATE TABLE table_63544 ("Children of Earth" TEXT, "Run time" TEXT, "Writer" TEXT, "Director" TEXT, "Original airdate" TEXT, "Viewers  ( including HD )  in millions" TEXT)

How many viewers were there for Children of Earth of 'day one'?
SELECT "Viewers (including HD) in millions" FROM table_63544 WHERE "Children of Earth" = 'day one'
SELECT "Viewers (including HD) in millions" FROM "table_63544" WHERE "Children of Earth" = 'day one'