Nozomi and I enjoy our evening walks in the park just shortly after the sun sets for the day. This is generally the best time as most people are home having dinner, the air is cool but not cold, and the sky can still carry faint hints of sunlight reflected through the atmosphere before the Earth's rotation moves us further into the night. Nozomi, being the puppy she is, generally keeps her nose to the ground. I, being the fool I am, generally look up at the endless expanse above. While the odds are beyond the infinitesimal, I would very much like to observe a vehicle from another world as it flies through our atmosphere.
Unfortunately, this will likely never happen.
There is no doubt in my mind that intelligent life does exist somewhere else in the universe and that our own galaxy should be teeming with life as well. I have no evidence for this assertion, of course, but the math in Frank Drake's equation — even at its most pessimistic — posits that there could be as few as 1000 different intelligent species in our Milky Way galaxy, and there are trillions of galaxies in the observable universe. Given the age of the universe, there's a good chance that some of these intelligent species will be vastly more technologically advanced than we are, and there will be some who are vastly less technologically advanced as well. Given the opportunity, I would become a xenosociologist and xenohistorian to learn everything I could about every one of them. Their culture, history, food, behaviour patterns, pastimes, likes, and dislikes would be absolutely fascinating. Even if a planet were found to have a population of people who look and act just like us — which is mathematically feasible, given the size of the universe — observing these people would reveal so much about ourselves as well.
This desire to learn about other species is likely not limited to humanity alone, which means that, given the means, extra-terrestrial visitors would undoubtedly want to learn as much as they could about us. Given that we've been on the cusp of interplanetary travel for several dozen orbits of our home star, this should make us a very interesting subject. Would an interstellar group of scientists travel all this way to study us in our natural environment only to spoil that study by revealing their existence to us, though? Most likely not.
When someone is being observed, their behaviour patterns change. Countless studies show that this is true in most mammals on this planet, not just humans. So if a vehicle from another star system were to enter our atmosphere, let alone get close enough to a population armed with cameras, they would need a rather pressing reason to do so. Alerting the world that we're all specimens for a technologically-superior group of aliens would not sit well at all with a large number of people. We would enter another technological arms race. Could we develop the technologies and tools necessary to combat vehicles that clearly have the technology and energy required to safely cross trillions of kilometres of interstellar space within the lifespan of the vehicle's occupants? Could we learn to hack their computers? Could we learn to communicate with them? Could we open a mutually beneficial dialog that would open the possibility of friendship?
Any intelligence that has been watching us for more than a season would see that we are a paranoid, violent species. Any knowledge of their existence would need to be kept under wraps until such a time as first contact — assuming there is a protocol — is initiated. Just going by recent history, if we were being watched, we'd find a way to hunt these visitors down, take their technology, and use it against them. Some might say this has already happened at Roswell and other locations around the world, but too much just doesn't add up when looking at those "recovered craft" stories.
Rational considerations aside, I will still look up at the night sky when walking outside with Nozomi. Even if I can't see a remarkable machine from beyond our solar system, there is still a lot of other wonderful things to look at and enjoy.