No one has really given a logical answer to this question lol.
There are multiple planets (moons) in our solar system that scientist believe contain "living life forms". Now depending on what your idea of a "life form" is, this could be pointless.
There are a couple moons that circle Saturn (and maybe Jupiter) that scientist believe could contain life, or contain attributes to maintain human life. One of which is completely covered in a thick layer of ice that they believe has water underneath, which could lead to an underwater species, or bacteria that could survive in that harsh conditions.
Another, named Titan, shows an atmosphere such as that of earth (eh, similar). Which could contain life forms.
So are there "aliens" out there? Very possibly, heck if were the smarted thing in this universe, we're in trouble :dodgy: