Time for some crazy maths:

I'm going to use some current best guests and estimates, but don't let this subtract from the point I'm making.

Firstly we need to work out the number of stars in the universe. Our galaxy, the Milky Way, contains approximately two to three hundred billion stars. There are about one hundred billion galaxies, so (assuming all galaxies average at the same amount of stars as our galaxy) we have approximately 2x10(22).

Now we need to weed out a large number of these due to inhospitable zones; these are areas such as those close to black holes where the microwaves steralise the stars planetary systems, etc, etc. Current estimates base this as around 9/10 of stars in inhospitable areas, leaving us with 2x10(21).

From astronomical observations, it is noted that around 50% of all stars have planetary systems; so, we're now down to 10(21).

Fourth, many exoplanets likely do not possess the conditions we consider necessary to support life (water, appropriate temperature ranges, appropriate elements and minerals, energy sources such as sunlight or planetary heat, etc.). A reasonable guess might be that of those possessing planetary systems, only one star in ten will hold a planet that is habitable. This gives us 10(20) habitable planets.

Fifth, we do not know if life will always arise on habitable planets. If, as is turning out to be likely, the molecules from which life originates can form in space-ice, then probably all of the universe’s planets will have been inoculated by now. How much of this material then goes on to create life can only be a guess. Presumably, if the right conditions exist, eventually all will; but, to err on the conservative side, let us say that only one in a hundred habitable planets becomes a host to life. Thus about 10(18) (1,000,000,000,000,000,000 or one quintillion) life-bearing planets possibly exist in the visible universe.

I really like those odds.

yes it does. even the Hubble telescope cannot see the surface of other planets but there must be life on other planets if there is life on earth. there must be planets surrounding stars with the same size ratio as the sun and earth and that can support life.

Our universe is massive, and I think it naive to believe ours is the only world to creatures of intelligence such as ourselves. I recall there being speculation that life could have existed on Mars, and if that turns out to be true, than I'd say it's highly probably life exists elsewhere and perhaps has evolved much like ourselves.

Whether we've been visited by said life . . . well I'll leave that to the conspiracy nuts.