"The Lubavitcher Rebbe pointed out that there is support in Torah for the notion that life exists on other planets. Furthermore, we can know something about that life through deduction from what the Torah tells us. Here is his argument:
In the Book of Judges 5:23, Devorah the prophetess sings about the victory of Barak over Sisera. In her song, she says, "Cursed be Maroz! Cursed, cursed be it's inhabitants, says the angel of G-d!"
Where is Maroz, and who are it's inhabitants. The Talmud gives two explanations, one of them being that Maroz is a star or planet. The heavenly bodies had also come to help the Israelites, as Devorah stated just one verse earlier, "From the heavens they fought, the stars from their orbitsâ€¦". This star, however, which was the dominant star of Sisera, apparently did not come to their aid. And so, General Barak penalized Maroz--and it's inhabitants.
Are these inhabitants intelligent? Intelligence is defined by Torah to mean the capacity to make decisions with free will. Free will is only possible where there is Torah, whereby the Creator offers His creatures more than one possibility and asks that they make the appropriate choice.
So, if there would be intelligent life elsewhere in the universe, those creatures would have to have Torah. Could they have a different Torah than us? This is not possible, since Torah is truth, and there cannot be two truths.
Could they then have the same Torah as us? This also seems impossible, since the Torah itself describes in detail how the Torah was revealed on this planet, and that account itself has strong impact on how the Torah is to be fulfilled.
It therefore appears that, although it is quite possible that there is life on other planets, however that life would not be intelligent in a way to similar to human life and culture."