updated 8/18/2011 3:49:06 PM ET 2011-08-18T19:49:06

I'm fed up.

Yet again, a few days ago, someone told me they saw a UFO in the early morning sky and immediately assumed it is unquestionable evidence that aliens exist and that they are visiting Planet Earth, raping and pillaging the locals!

After a big sigh, and a little sly questioning on my part, we discover they had witnessed nothing more than Venus rising in the dawn sky and the flashing lights were the distorting effect of the atmosphere.

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A few months ago, at our street party celebration for the Royal Wedding, I convinced the neighbors to launch some Chinese lanterns. It turned out that the fleet of orange lights floating silently across the sky was mistaken by an alarming number of residents nearby as a whole invasion from bog-eyed monsters! I mean, really...

There seems to be an alarming increase in UFO sightings (and UFO hoaxes) and sadly, less common sense being applied to possible explanations.

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I can't help but hark back to the fact that I'm an astronomer, have been looking at the sky lots -- and I mean lots -- over the last 20 years, and have yet to see anything that has aroused my suspicion. I think it's fair to say that all of my astronomically-minded friends and colleagues have never seen anything that makes them think we are receiving visits from out interplanetary cousins either.

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I am, however, very aware that there is a whole host of professionals, from police officers to airline pilots, who have seen something out of the ordinary. UFOs? Of course! After all, these things seem to be "flying" and are "unidentified"; but little green men? I think not.

For me, it's a matter of numbers. The Universe is around 14 billion years old, yet life on Earth has only been in a position to travel in space (and pretty slowly at that) for the last 50 years or so. Work out the numbers and the only civilization we know of has only been space 'savvy' for the merest fraction of the age of the Universe.

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Also consider the size of the Universe: it's BIG! What are the chances that two civilizations emerge at approximately the same time, and in reasonable proximity to each other, and develop the technology to travel in space, or even communicate with each other? The answer, all be it a qualitative one, is a very, very small number.

It's perhaps an appropriate aside to think briefly about the evolution of the Universe, too.

Many of the atoms inside our bodies are 'heavy' elements, carbon and iron for example. These elements were produced inside the core of the first generation of massive stars and were spread throughout the Universe when these stars exploded as supernovae.

Eventually, over many millions of years, a "second generation" of stars formed with planets made out of those heavy elements, and with that came the possibility of life. So it's perhaps reasonable to conclude that any other civilizations might only just now be evolving to a sufficiently advanced level to take those first tentative steps into the Cosmos. This might increase our very, very small number by a tiny bit, but not a lot.

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Even if ET is out there and zipping through space, I find it hard to imagine that they would make the effort to come all this way and not make more of the opportunity to engage with us.

No, I think that UFOs being of alien origin is highly unlikely. I'm not disputing the countless sightings, just the irrational assumption that they're alien in origin. I think it's much more likely something that has just been misidentified or the result of some very advanced earth based technology.

If I'm wrong, then I'll eat my hat!

© 2012 Discovery Channel


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