[Moonman62]

There is only one data point. And that is us. All else is speculation. However, using probability, we can make some predictions. Thusly was born the "Drake Equation".

What about all the other lifeless planets and moons we can observe in our own neighborhood?

[RadioAstronomer]

What about all the other lifeless planets and moons we can observe in our own neighborhood?

They fall out side the life zone and/or are not the correct size to sustain an atmosphere. We are just beginning to explore our own neighborhood. I remember a professor telling us once that he never expected us to find any extra solar planets. Well, we have more than 100 now. For the record, I do not believe there are life bearing planets out there; however, I do suspect there are.