The galaxy is 100,000 thousand light years across and rotation occurs at 200 Million years. If an intelligent extraterrestial species were to exist, the key question is what evolutionary stage exist within their society? Humans have only had advanced technology for the last 100 years, the understanding radio waves. If an extraterresial civilization existed, would it be analogus to "Hunter and Gather" or "Egyptain/Roman" or "Pre Industrial" or advanced to "Planetary Terraformers"?
Even if intelligent extraterrestial life exists, for communication to occur--it would have to be near by--within 50 light years. Wherein, generational messages would be exchanged between humans and 'them'.
It is a assumption, that as a intelligent species society developes, the attempt to find another intelligent species would occur through the use of technology, and that the two would share open discussion of knowledge. For example, was there an exchange of knowledge between Humans and Neanderthals, or the extinction of a species by another?
What if the extraterrestial intelligent species is 2,000 light years away--would they want to "Make Contact" with humans and Why?
Human history includes "The Dark Ages", when our society collapsed after the Roman Empire fell. This could occur in our future, as well, from Global Warming and the spread of bacteria across the globe--a world wide population crash. Which did occur 74,000 years ago with the human species.
Intelligent Extraterrestial life, will have had simular events in their own history, if 'they' exist.
If 'they' existed with advanced technology, they probably looked out into the galaxy--didn't find any signals or possible indications of primative non technological life. They therefore, would begin terraforming activities on some nearby worlds and planets or solar systems. The solar system society that occurred, could have further advanced or collapsed.
Human scientific minds, collectively might discover extraterrestial life--bacteria on Mars, Venus, or Europa, all within the next 20-40 years. They might find, an extrasolar planet with potential extraterrestial life, within the next 20-40 years. Intelligent Extraterrestial life...humans probably will evolve into what is being sought, over the next 50,000 years.
So, why worry about some "Greys" in spaceships, or Darth Vadars--they don't exists. Worry more about the bacteria and viruses from this world, as a population crash could occur from global diseases.

I liked the show very much. Finding these "earth-like" planets is very exciting. The concept of planets like Aurelia with only partial areas available for life to exist was amazing (the rest being taken over by freezing temperatures and hurricane tempests!). I also appreciated the animal concepts contrived by the scientists, however the show did raise a few questions for me on these fantastic creatures and how the scientists chose the anatomies of the fantastic creatures, such as the 'stinger fans' and 'gulphog', resembling the ostrich on earth.

I'd like to hear from the scientists a differentiation between aspects of the anatomy which would be required to exist on the alien world, and those aspects which would be very similar to life here on Earth. In other words, what makes these creatures alien, other than the fact that they don't exist on our planet? What causes these changes in evolution to take place? Distance from the sun? Composition of the atmosphere? I appreciated, for example, the analysis of creatures in "Planetary Investigation Lab" on the Blue Moon, which would be able to navigate between water and air as a result of the thick atmosphere. I liked the data compilation of these planets especially, and their presentations, but I wonder if the scientists couldn't flesh out a bit more the differences geographically between Earth and these planets and how those differences transfer to the life forms? For starters, which of these aliens could not exist on Earth and are there many animals on Earth which could exist under these conditions?
-BB, student of Astronomy at Middlebury College in Vermont

An excellent show. Me and my son enjoyed it very much. We must remember that we are just getting started in the search to understand our place in the Universe. It was not long ago that we thought the Earth was at the center of the Universe. Indeed, many religious organizations would like nothing more than to keep teaching us this self-centered belief system. Intelligent life with the ability to create machines that can study the Universe around them is probably very rare, but life in less intelligent forms is probably common. Given the right conditions, life will take hold and Evolve. Those people who say that there is no other life in the Universe are in for a surprise; Those days are as numbered as when Culombus was ready to set sail. Will they finally be willing to learn?

it has been seen by many of us to be true already that truth often is far stranger than fiction.so it only stands to reason that since there are more stars in the universe than grains of sand on our own planet that if each star had only one single planet,that more than a small handful might be at the right distance from their star to produce lifeforms.taking that as a starting point,the forms of intelligent life that might be out there and what they look like should prove to be more diverse than ones own imagination could conjure up.how arrogant and naive would we be to think ourselves the only intelligent species in the universe,after all wasnt it mankind who once thought the earth was flat,or maybe the time we thought the earth was the center of our solar system-hmmm think about that...........

The existence of Extra-Terrestrials assumes that the THEORY of evolution is true. Believe it or not it is just a theory...funny how it's taught as fact in every institute of learning on this planet. I have just as much fun dreaming about life on other planets as the next guy. But if evolution WERE true we would be finding life of all sorts in our own solar system. That's why scientists are so eager to find it life it would give a scrap of credibility to a THEORY. Which is as of yet, not proving true on the planetary level. So what’s wrong here? Where is all the evidence?

Hello There!
I am amazed of the imagination of human being.
Imagination has done all the advances in technologie and science and it is costing our own destruction.
Imagination has produced that human beings be away from their own environment. We are always dreaming; there are millions and millions of alive things just around us and we are wondering if there is life far away at the stars.
Please humans go down on Earth, wake up, leave sky and try to save the live here on Earth and even we dont know but we are destroying every minute.

I do not understand why we are so fascinated with extraterristrials? Why don't we do something about preserving what we have on earth and getting rid of violence and hatred among humans.

I couldnt find an appropriate place to comment on the show, so Im posting here. I watched 20 minutes of Extraterrestrial and turned it off. It was awful. I might watch the rest, but I was dumbfounded by what I saw. Please note, before I get flamed, I only watched 20 minutes. First, the fancy Star Wars holograms of the planet. Please, you arent Industrial Light and Magic. Put your effort into the science, not special effects. Second of all, they never explained why they werent looking for start similar to out Sun. Fine, red dwarfs might support life, but we have a perfect model for supporting life in our own Sun. They never explained that. Also, the fans, or whatever they were called... they made no sense. If we are to assume that Darwin's Law of survival of the fittest applies to all life. Wouldnt the faster and stronger fans have evolved? Not these slow moving tree like things. Either force your way to the best spot with power, or hold your spot like roots of a tree. And im no biologist, but with a beating heart and moving muscles, wouldnt it take a lot more energy then solar power could provide? Seemed to unbelievable. And the predators, whatever they were called. If those fans or animals, why didnt they get eaten? It would seem to me go for the easy slow moving meal which was quite large and quite plentiful.

Sorry, just my thoughts. Maybe I will watch the rest of the show. I dunno, it would seem to be a waste of our tax payers money to fund NASA scientests to come up with things that an elementary school student could poke holes in.

Another question runs to size and the amount of energy available. With the question of nitrogen (ammonia) - based life, or whether or not Titan is too cold to be anything but pre-biotic, it does raise questions about convergence and biomechanics.

As implied in the special, dimensional analysis and fundamental physics suggests ideas about scale in varying environments. I don't know enough about the fundamental equations, but could it suggest that by varying temperature, we could get viable figures for creatures of a different size?

The other thing that did pop into my mind during the show is what about the notion of habitable planets with very high axial tilts (approaching 90 deg), you get the same effects as tidal locking, but I would imagine the corolis effects would make the central hurricane problem just monsterous. On the other hand, it might generate enough circulation to keep some portion of the night-side warm.

If nothing else, the whole concept of a central cyclone on a tidally-locked or high-axial tilt planet is interesting because of the implications for fresh-wtaer hydrology.

All in all, good food for thought.

Keep blogging (even if you don't have time for comments)!!!

I cannot believe that leading astrophysicists or climatologists would agree with the potential that the two "worlds" presented here could sustain advanced life forms.

The first planet, what was it, Ariel? A planet with no rotation. Yet is has liquid water. How, all evaporating water would parcipitate on the frozen side. Also with the source of heating and cooling being stable, the wind speeds generated by basic thermodynamics would be so great as the "Stingers" fronds would be ripped to shreads. And to top that off the UV-A radiation generated by the red dwarf would decimate the life before it could reach multi-cell level. There would have to something similar to the upper atmospheric phenomon as can be found on earth. Granted a gelogically active planet would also have to have a electromagnetic field as well as some form of an ozone shield to support carbon based life. The ozone shield would more then likely be present not due to the gelogical events; but due to the ionizing energy given off its sun. Yet, what is the liklyhood of a duplicaton of earths atmospheric
characteristics, about the same as there is for life on other worlds.

As to the second world, "Blue Moon". Advanced life requires stability in temperature with the moon in an equatorial orbit around a Gas Giant is diametrically opposed to this possibility. Now if the "Moon" was in a Polar orbit this may be a possibility. However the electrmagnetic and ionizing energy would be so great from the Gas Giant and to make carbon based life nearly improbable.

I understand that there are great variations and that life can exist in a number of unusual environments; however, for advanced life beyond single or minor multi-celled organizisms, it seems fairly unlikely except in extreamly rare cases. Even then the chances for the perfect ballance to exist long enough for advanced life to from, it makes the chance of finding life on our same time scale very unprobable. But, who knows...

This experiment in fantasy is too much fantasy and not very deeply based in actual science. But, that is only my opinion. I guess I should not tread on other people trying to spread their wings of the possible. I just think keeping in mind more basic science before building a fantasy non-existant world would better serve a international periodical of science and discovery.

((Can't Wait to see the show tonight))

There IS life out there, the sun is a star and there is a massive
number of stars, and the sun gives life (warmth for life) and in the infinite space, there has to be life.

The whole concept is natural to me. I am a qualified chemist and it occured to me when I was about 20 (7 yrs ago) that it is all dependant on chemistry. It was an X-file that got me thinking, it was the one at Antarctica with the Ammonia based life form...you may remember it. Anyway life on Titan seems 'weird' to us, who occupy 30 deg C, with plenty of liquid water around, but it is just as conceivable that life exists outside of this relm of chemistry. Of course there are things that are definate precursors, and these I believe are:

Some sort of building block, for life on earth it is carbon, and it is most likely to be carbon elsewhere, but Silicon is another possibility. Its symmetrical and the bond is strongest in carbon - think diamond.

Liquid water - for obvious reasons but for those who do not know water has unique chemistry

The last one is temperature. The hotter (within reason) the faster things will evolve. I predict that with all things being equal, a more intelligent life form will evolve faster and come to us from a hotter environment, which of course poses more problems thaan we currently have with regard to space travel. For this reason life on colder planetary bodies is likely to still be in the very primitive form of micro organisms - the most probable birth place of any advanced life form.

As for convergent evolution, I have never thought it weird to consider the dinosaurs may have evolved (given the chance) to look alot like us in stature and shape given long enough. When I realised that we nearly had 'aliens' on our planet, it all just seemed to fit together easier.

Just a few thoughts, hope you enjoyed.

sencerily my dear fellows, if there are other race as or more intelligent than us in space I think the will also have the same curiosity to know what else in space and maybe they would already make contact with us. The fact that we have not have signals of intelligent races in other planets just probes that if there is any life out of the earth, they are no less stupid(or even more) than we are.

In the infinity of space and the billions of years that the universe has been expanding- one can only conclude and aspire to something more than what we know...
if there is life out there I would like to know...
I wonder that if we we were to discover life-more intelligent than our own-that we would percieve it as a potential threat.
Burrying one`s head in the sand is probably natural.
our whole existance and curiosity are what makes us what we are...
Where did we come from?
perhaps the answer to the future lies with our past..

just a thought

Since I can remember seeing Sputnik in the sky when I was a small child I have always been fascinated with what is out there. As an adult I happened to work in an industry that make communication devises for the space program in the 70s. Those years were some of the greatest of my life. All of the people I worked with were so excited about the space race and the possible chance of discovering aliens on other worlds. I even had dreams of someday that my grandchildren would vacation on the Moon. Of course, now my grandchildren are here but we are no where ready to vacation on the Moon. As technology expands and as the world's people come together through better understanding I still have hope that the next generations will discovery that we are not alone in the Universe. It is mankinds destiny to explore it is built into our genes.

I have noticed that as humans we can be very arrogant and so it is natural to think that we have the ultimate body type, but now it is time for us face the facts, we must accept that there is no ultimate body form, it depends on the enviroment of the being's habitat, forms of communication, and the food it eats. An intelligent being may be eight feet tall, have octapedal locomotion with a skid for a tail, communicate using bioilluminessence, and have a skewer-like beak for killing its prey and then sucking it dry and that could be the prime form for that planet. I don't care about what Steven Hawking says about "keeping our heads low" as "the history of more advanced civilizations meeting more primitave civilizations [not being very happy]", there is nothing to say that the other advanced civilizations out there are war-hungry monsters. There is some evidence of an advanced civilization (I do not know the name of the signal) that was picked up at The SETI Institute that was clearly artificial. I know there is something out there, and I know we will find it.

It goes against mathematics to think we are the only 'intelligent' civilization in this Universe, let alone this Solar System.

BY THE WAY WE SAW THIS CRAFT IN BROAD DAY LIGHT THE TIME WAS 7 PM
STILL DAY LIGHT HOURS, AND ONLY A MILE AWAY, YOU COULD SEE IT WITH NO PROBLEM.WHY THIS CRAFT STAYED THERE THAT LONG FOR US TO SEE IT I DONT KNOW. BUT IT WAS TRUELY AMAZING. SO YES THERE IS LIFE OUT THERE. AND THE MORE I TALK WITH OTHER PEOPLE ABOUT THIS, THEY SAY THAT THEY SAW SOMETHING LIKE THIS TOO. BUT THERE EXPERIANCE WAS DIFFERNT THAN MINE. SO THERE YOU HAVE IT.

WE ARE NOT A LONE ON THIS PLANET.

IS THERE LIFE OUT THERE?
WELL I CAN TELL YOU ME AND MY SON PERSONALY WITTNESSED A VERY LARGE CRAFT JUST A MILE FROM MY HOME. AND IT HOVERD IN ONE PLACE FOR ABOUT 5 TO 10 MINUITS AND WITHOUT A SOUND. YOU WOULD THINK BEING THAT CLOSE AND THAT BIG THE SIZE OF 2 LARGE HOMES IT WOULD OF BEEN VERY LOUD , NOT A SOUND CAME FROM THIS CRAFT. IT STAYED THERE LONG ENOUGH TO DETERMINE WHAT IT WAS. OF COURSE I DIDNT GET A PICTURE BECAUSE I DIDNT HAVE ANY FILM. BUT I AM A SCEPTIC YOU CAN SAY , BUT WHEN I SAW THIS CRAFT, ALL I CAN SAY IS I KNOW WHAT I SAW AND IT WAS A SPACE CRAFT, A VERY LARGE ONE, AND NOW I KNOW FOR SURE WE ARE NOT A LONE. I DIDNT SEE WHAT WAS FLYING THIS CRAFT. AND BELIEVE ME IT WAS NOT A WEATHER BALLOON OR THE STEALTH EITHER. BUT THE ONLY THING I CAN THINK OF IS E.T. WHAT ELSE COULD FLY SUCH A CRAFT. BUT I KNOW WHAT I SAW, AND THAT'S ALL I CAN SAY. I DONT CARE IF ANY ONE BELIEVES ME ARE NOT. SEEING IS BELIEVEING ENOUGH FOR ME.

I can't wait to see the special. I have always had an interest in life on other planets. I just can't imagine the creator of the universe creating all of the stars and planets and have life only on one planet. Why create such a vast number of planets that would be of no use. We here on earth are a part of something bigger than we could possibly know. Maybe one day we'll know why we are in that great plan and who else is included.

Wish my cable provider had The Nat Geographic channel, I'd like to see this. It seems similar to a show recently shown on The Discovery channel called 'Alien Planet'. That was more science fiction or fantasy than it was science though, but it was pretty good.

Anyhow, I guess Ill have to wait till this is shown on another network, one that's part of my cable lineup.

Good job, Seth - your a voice of reason about this stuff, even when you're on the... nutty Coast-to-Coast radio show.

Regarding optimal design, there may be good reason to think that the features we share with intelligent extraterrestrials may be a result of the old prey/predator relationship. The animals on earth with the highest I.Q.'s seem to all be predators (majority anyhow) that need the better stereoscopic vision, hearing, more effective grabbers, etc. The optimality you mentioned must be optimum for a purpose, usually that is grabbing a meal that is trying to get away.

"...ferrying snacks to our mouths."
That's Funny.