Our home galaxy, the Milky Way, is said to contain approximately 300 billion stars. This alone is beyond my tiny little brain's capacity of comprehension. Scientists are now discovering other planets whizzing around some of those distant stars in just the same way as our Earth orbits the sun. The more the scientists gaze out with ever more sophisticated technologies, the more of these so-called exoplanets they find.
To date, around 4,000 exoplanets have been discovered in The Milky Way alone. Considering that there are approximately 200 billion other galaxies in the known universe, it kind of seems unlikely that life has only managed to flourish here on this one tiny planet - Dr Carl Sagan's 'pale blue dot'. Even a boring old sceptic like me understands the probability that there could be some kind of extra-terrestrial life out there.
Exploring such mind bending facts was the last thing I'd intended to do after arriving in central Portugal. Far from it. My intention had always been to arrive at the beautifully tranquil town of Constância and simply chill for a few days. As sure as eggs is eggs, the Constância sun was shining, it felt wonderfully warm and there was always a shady riverside promenade to cool down if it got too sultry. Of course, Constância boasts some equally wonderful riverside cafés to help with that uniquely Portuguese relaxation process.
My choice of hostelry was Quinta de Santa Bárbara which is conveniently located on the outskirts of Constância. This is a 15th Century Manor surrounded by landscaped gardens. Originally owned by a friend of Camões, Portugal’s most renowned poet, the hotel is a place steeped in history. Later, in the 18th century, the Quinta became the property of Jesuit priests who lived there until 1759.
But more to the point, the hotel is a mere five minutes away from Centro Ciência Viva de Constância (Astronomy Park). This makes Quinta de Santa Bárbara an ideal base for Astronomy boffins from all over the world to congregate and mull over the many wonders of Portugal as well as pondering the wonders of the wider universe!
It was whilst staying in the company of such astro-boffins I learned how scientists already know about hundreds of potentially habitable planets. Apparently they are able to measure the atmosphere on such far away worlds by using a method known as spectroscopy. Starlight passes through alien atmospheres allowing experts right here on planet Earth to perform a series of chemical analyses. Should they happen to detect the kind of substances found within Earth’s atmosphere, they don't immediately presume the presence of life. However, such findings may well provide a strong indication that alien life is actually possible.
A talk given at the planetarium revealed that life on Earth has been discovered in some extremely forbidding places. Areas where only a few years ago no one ever thought that life could possibly flourish at all. So now, when scientists contemplate the existence of life beyond our own planet, they look at how science has discovered microbes inhabiting places here on Earth where the notion of survivability was once inconceivable.
Whilst all terrestrial lifeforms share familiar DNA profiles, some have managed to evolve in such a way that they can eke out an existence in deep ocean trenches where there is no available sunlight. Scientists once thought that life could only exist on planets that were a certain distance from their local star which might provide enough light radiation for simple life to develop. Discovering life flourishing in environments where it once didn't seem feasible has opened up the possibility that there might be planets or even moons that may be able to support life.
Microbial life swimming in some kind of alien primordial soup or hiding under an extra-terrestrial rock is one thing; finding intelligent life living in complex societies or even in technologically advanced alien civilisations is quite another. Even if such advanced beings do exist, they will be subject to the same laws of physics as humanity faces in our own solar system and indeed right here on Earth itself.
Extra-terrestrials would face the exact same constraints when it comes to the complex business of interstellar communications as we do. Sheer distance poses the same obstacles. Even communicating with a civilization in the centre of our own Milky Way, some 25,000 light years away, would be nigh-on impossible. Any messages sent would take roughly 25,000 years to reach them and then a further 25,000 years for us to hear their reply. That would be one frustrating 50,000 year long WhatsApp exchange! Then, try messaging other galaxies! I think you'll appreciate the difficulties here.
As things stand, it's largely beyond human capabilities to even send a large spacecraft to Mars, our nearest planet. Any notion of human interstellar travel only lives in the fantastical imaginations of Hollywood movie makers.
Even if any alien civilizations possessed all the right technologies to survive a trip to Earth, they would surely need to be desperate to ever contemplate embarking on such an odyssey. I dare say, their astronauts would not be overly enamoured by the thought of traveling for tens of thousands of years simply to perform a meet and greet exercise. If they somehow did know what our Earth looked like 25,000 years ago when they set off, what they'd behold here today would be an absolute shocker.
My own home-grown hypothesis indicates that if such an advanced race did exist, it would surely have been formed by entities who possess a degree of logic? My own simplistic logic denotes that humanity surely doesn't possess anything that such a hypothetically advanced race could ever possibly want or need. And this is why I suspect that E.T. (if he exists at all) will never bother dropping by planet Earth. Aliens would simply be happier, safer and way better off by staying where they are - on planet Zorgg.
On my last evening in Constância, I sat on a camp chair by the planetarium amidst a bunch of Astronomy boffins. We all gazed at the magnificently clear Portuguese night sky and contemplated the sentiments of the late, great Dr Carl Sagan. He wrote the following amazing words after studying the famous 'pale blue dot" image taken by the Voyager spacecraft as it spun around to take one final glance at 'home' before leaving our solar system forever:
"It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known."
Tell that to the politicians!