[mysterio]

That being the case, evolution on other worlds would probably follow the same rules and come up with a dominant life form that would look pretty much similar to what we developed into.

If their native planet was identical to Earth. What if it's bigger/much greater gravity? What if they don't breathe oxygen?

These aliens are never seen wearing space suits, so I assume they breathe oxygen. They have limbs like ours, so I have to assume their gravity is similar. So, we are left to believe somewhere out there beyond the stars there's a planet just like earth that produces space aliens who look nearly identical to us, yet cannot be photographed and leave no evidence of themselves.

Not likely.

[Ronin]

Who knows?

But think it through. If they didn’t breath oxygen, why would they bother visiting a planet where oxygen is used? The only reason we are mucking around with Venus or Mars is because those are the only planets we can reach.

If we had interstellar travel, we would be out looking for earthlike worlds. I would imagine that any alien society with star travel would look for planets as close to their own as possible. I doubt we’ll bother with Jupiter for anything.

It’s all speculation, and as a science fiction fan, I like to speculate. Also, as a science fiction fan, I find ufo freaks to be somewhat amusing and don’t take them seriously.

But I don’t discount them completely. Too many of those reports have been made by extremely serious folks.