Is there intelligent life on other planets? Yes, there’s life out there, say the sages of the Talmud and the Zohar HaKodesh – but it’s not so intelligent. The sages name seven “earths”, but ours is the one where Hashem created Adam, gave the Torah, and will establish His Beis Hamikdash (the Holy Temple) in Jerusalem.
Meanwhile, living on at least one of the other six inhabited planets are humanoid descendants of Cain, who was sent wandering in separate dimensions and far-flung corners of the universe as a punishment for killing his brother. Rabbi Zvi Aryeh Rosenfeld z”l describes this and much more in a lecture he gave over forty years ago.
ENTIRE LECTURE: Ein Yaakov – Lesson 177a