"Kizzy, Behold! The only thing greater than yourself!" cried Kunta Kinte, in the life story called "Roots". For a very long time before that 1970's TV series, a much younger Mark Willis had stared into the night sky and wondered what was out there.
Most people are humbled by the awesome majesty of the cosmos. Our tiny pale blue planet circling it's local star, called simply, the Sun, seems so fragile, like our own lives. The distance between our existence as living beings and being departed, seems so hair's breadth sometimes, when you reflect upon it. Our planet, being hurled around the Sun at 67,000 miles per hour, while we turn at 1,000 miles per hour, seems unreal. And yet, we live our lives, most of us, as though we are quite impervious to any dangers out there.
Kunte Kinte must have reflected upon what was in the heavens above him and his lovely daughter, like so many people before him and since. For centuries, people with inquiring minds, have always wondered that when they look at almost any star in the sky, it could well be the host sun to another planet like our Earth and on that planet too, there'll be people driving around in their cars, being late for work, getting married, getting sacked, dying and being born.
We cannot actually see stars that are the same size as our Sun, because our Sun, is a main sequence star. Our Sun becomes quite a lot dimmer, even just outside our own solar system, a few billion miles distant. Our Sun is a bit of a stellar nobody really. Not too small, not too big, but just right. I've learned that there are stars that are like ours, classed as a G2V star on the astronomer's stellar league table called the "Hertzsprung-Russell diagram".
It is fascinating to speculate on the possibility of life on other planets. What do we know so far? Well, from life in our universe, we know that in one solar system, 8 out of 9 planets, (I still count Pluto), seem unlikely to have life on them like us. One planet does have intelligent, (well the potential of intelligence at any rate), life on it. To look for life like us, it seems reasonable to look for another G2V star, with say, 8 or 9 planets around them. Find one planet that is, like Goldilocks and the three bear's porridge, not too hot, not too cold, but... just right.
Further, the same size, or nearly, as Earth and also, in order to have the porridge just right, be about 149 million kilometres or 93 million miles distant from it's Sun, which of course will have two different names. The name we've given it and also the name that the locals have given it.
With only one known planet bearing life, we simply have no way of being able to determine very intelligently, just how likely life is on other planets. It could be that there are 20, 100 or even 1,000 solar systems without any life in them at all. Equally, unlike our solar neighbourhood, there could be 5 out 8 planets inhabited with alien life.
There are stars about 11 light years away that are very like our own sun. Superimposing our own solar system knowledge over that 11 light years distant one, it might seem reasonable to assume that we could have another "Earth" quite nearby. If so, they may be able to, if they've developed technology like ours, be able to hear our radio and see our television, although with an 11 year delay. Programmes being broadcast today in 2007, therefore won't be picked up by them until 2018.
With only that one template of the only solar system we have, our own, to go on, it is very difficult to make anything but a best "educated" guess.
So from the dramatic proclaimation of Kunte Kinte, we end with Patrick Moore saying "Frankly, we just don't know!"
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