But maybe there's a simple answer.
The argument as presented by skeptics goes something like this: If UFOs were "real," the most would be seen and reported by those people who spend the most time watching the sky. Originally, the group of people that were considered most likely were astronomers, but it was quickly pointed out that most professional astronomers are too specialized and involved in academia to do much observing.
But amateur astronomers, on the other hand, do spend a lot of time observing the sky. They're the ones who really know what's up there.
A case in point: Ian Shelton made Time Magazine for discovering Supernova 1987a, the brightest of its kind. I went to school with him, and had the opportunity to talk with him about his discovery. When we were in undergraduate astronomy in university, we were in a hallway and saw a poster advertizing a job for a graduate student in Chile, maintaining the University of Toronto's observatory literally on top of an isolated mountain. Already a family man by that point, there was no way I could have considered it, but Ian looked wistful and said, "That sounds neat." He applied and got the job.
Several months later, he was walking between domes on the Chilean mountaintop when he happened to glance upward. Now, you have to understand that Ian was (and is) a very good astronomer. He spent a lot of time observing the sky. He was the best at star-hopping and finding Messier objects and galaxies by eye, and could pick out comets like nobody's business. He looked up into the Chilean sky and knew that one particular star, out of the thousands visible, was out of place.
Ian had discovered a supernova. But he was an amateur astronomer, since he did not have a PhD yet.
It's amateur astronomers who spend time with their eyes glued to eyepieces at 40 below (like I did in my undergraduate years) mapping the Moon's surface. Looking for comets. Timing occultations. These days, a lot of the chore is done by computers and digital imaging devices, but it's usually amateurs who monitor the equipment.
A friend of mine, Dave, is a brilliant amateur astrophotographer. (The qualifier "amateur" hardly seems appropriate.) His photos of the Owl Nebula, the Horsehead and Jupiter's bands are poster-quality. I asked him about his process, and he said that he sets up his equipment in his dark site in Texas before dusk. He waits for darkness, punches the coordinates of the star or galaxy he wants to photograph into the telescope's computer, and makes sure it's centered and focused... and then goes into his warmup shelter and has a beer. Or three. The methodology guarantees success.
But I digress...
It's true; amateur astronomers watch the sky more than most people. Of course, there's fewer of them than there are other people who might casually or accidentally watch the skies, so that's why most UFO reports come from anyone other than amateur astronomers. The other reason is because, as skeptics point out, amateur astronomers can identify most UFOs they see. That is, if the see an object they can't immediately identify, it only takes a minute or two to determine it is a satellite or fireball, of something else. It is true, however, that even experienced amateur astronomers file UFO reports about unusual objects they have seen whilst doing their observing.
But skeptics insist that most "real" UFOs would be reported by amateur astronomers. The reasoning is that if there were any real alien spacecraft approaching Earth, then they would be observed by amateurs' Earthbound telescopes. Also, since amateurs are often blogging or emailing each other about their observations, the news of an anomalous object heading for Earth could not be kept secret. That's how comets are discovered; similarly, asteroids and wayward satellites.
No such discovery has been bouncing around the astronomy ListServs, therefore, there are no alien starships coming to Earth.
UFO buffs, however, note some flaws in the reasoning. First, if we assume aliens are advanced enough to have conquered interstellar space travel, their technology may be more advanced than we can understand. In fact, why couldn't they be here or have come and gone already without our detection? It's kind of Stephen Hawking's suggestion that if aliens are technologically advanced, then they may be very technologically advanced; not just a few hundred years, but tens of thousands, or a million? If our own civilization lasted a million years, can we even conceive of what it would be like?
Secondly, amateur astronomers may be good observers of astronomical objects, but would they be able to identify objects within their own frame of reference? If a UFO flew over their observing site, would astronomers notice it, and if so, report it?
Some note that the tenet that "UFOs are nonsense" among the scientific community is very strong in astronomy circles. Amateurs might be very hesitant to report their observations, thus the percentage of UFO reports among this demographic might be artificially lower than the general population, which has less of a social stigma in this regard.
But another possible explanation was recently noted by my wife, whose insights are always significant. In her research on an unrelated subject, she came across a reference to a famous psychology experiment that may be relevant to this issue.
The experiment was performed and results published by Daniel Simons and Christipher Chabris in 1999. (Simons D J, Chabris C F, 1999, "Gorillas in our midst: sustained inattentional blindness for dynamic events." Perception 28(9) 1059 - 1074.) They noted:
Our results suggest that the likelihood of noticing an unexpected object depends on the similarity of that object to other objects in the display and on how difficult the priming monitoring task is.
For the experiment, they filmed a scene of several people passing a basketball to one another, and showed the film to a group of participants in the experiment, asking them to note how many times the players in white shirts passed the ball. As much as 70% of the time, the viewers counted the passes correctly, but failed to see the guy in a gorilla suit walking through the scene.
View the clip at: http://viscog.beckman.uiuc.edu/media/ig.html
The phenomenon of inattentional blindness occurs when people are focused on a specific task and ignore other things around them. This could be one reason why so many people can be out observing the sky and fail to see something out of the ordinary flying overhead. This would be most relevant for professional observers of the sky, like pilots, meteorologists and astronomers.
In other words, an astronomer observing the night sky, looking for comets or simply tracking a planet's progress for astrophotography, might not observe a UFO moving in the area. It;s the focus of one's attention that prevents observation of things not of interest. And UFOs are definitely not of interest to astronomers.
