A while back I saw a news item about the discovery of a visible planet orbiting the star Fomalhaut. Television news showed a brief video clip simulating the planet's orbit. It seems to be following an eccentric orbit around the star and approaching quite close to the star. It's not a plausible candidate for supporting life of any kind but it should finally settle the hash of any remotely sane skeptic on the topic of the existence of planets outside our solar system. That is, if all the gravity-distortion data hasn't convinced them already.
It was only a few years ago that there were astronomers seriously proposing that our solar system may be the only one in the universe with planets or that ever has or will have them. How anyone could be that far into solipsism beats me from here to Brisbane. Was it ever remotely likely that in all of space and time our star system was so defiantly unique? As a hypothesis it really should have been relegated to the category of the infinitesimally probable during the nineteenth century.
I don't put much stock in the prospect of aliens pestering us in the recent past or future but I think it would be ill-advised on the same scale as the "no other planets" hypothesis to hold to an absolute denial of their existence. Of course, most other life in the universe will be of the sort which existed hundreds of millions of years ago on this planet. Other types may have progressed in a more benevolent star's orbit, where the extinction events which have disrupted the history of our planet may not have occurred. This could put them ahead of us intellectually and technologically. Of course, Nature being capricious, a planet which has been subjected to great plagues of extinction events may be harbouring a supremely adaptive and relentless species which is just about to take over the Universe. (In which case, let me be the first to welcome our new overlords.)
I was reflecting today on the indifference of these facts of Universal life to our opinions and perceptions. These alien planets have been there through all of recorded history and well before it. If they are trees in the Galactic forest, no human observer has been required to permit their growth or fall to occur. And there are probably wonders and mysteries out there which we may come and go without ever knowing or even imagining the existence of.