“IT’S LIFE, JIM, BUT NOT AS WE KNOW IT”
Fifty years ago, that great American astronomer, cosmologist and astrobiologist, Carl Sagan, pioneered and promoted the Search for Extra-Terrestrial Intelligence (SETI) project.
Sadly, Sagan died in December 1996 and never saw any success in his quest.
It seemed like an impossible task, to find another Earth-like planet out there, one that might be able to support life among the billions of stars. But on the 21st of April 2009, Swiss scientists did find one. It was chance in several billion, but there it was. Orbiting the red dwarf star identified at Gliese, located north of the brightest star in the constellation of Libra, about 20 light years distant, within what they call “the habitable zone”, was a planet of Earth size which they designated Gliese 581C. It was a first, and they were very excited. But they found others, including Gliese 581D.
So-called habitable zones are at a distance from a star where the climate might be relatively temperate and there would be a possibility of water. Take our own solar system as an example. Venus is too close to our star, the Sun, and is unbearably hot under a thick noxious greenhouse atmosphere; Mars is too far out and temperatures are too cold. But in the space between these two lies the Earth, in the midst of a zone where the sun is not too hot to kill us or to evaporate off all of our water, and where life can grow. All kinds of life: animal, vegetable, microbial – everywhere you look on Earth, in every possible niche, some living thing finds an existence. That’s the point. Wherever life can find a place to live, it does. Life thrives. So why just here on Earth? Given the millions of potential places it could exist in some form, why would we think it could only happen here?
The question is this. Is our blue planet unique in the whole universe? Are there other Earths out there? Scientists, following Sagan’s hypothesis think there are – they reckon there to be at least 10,000 Earth-like planets out there. The problem is finding them.
It has been calculated that our own Milky Way and the neighbouring Andromeda galaxies have about 100 billion stars between them, and the known universe may have in excess of 100 billion galaxies. Multiply 100 billion by 100 billion, and you get some idea of the magnitude of the problem! Truly astronomical! The chances of finding a suitable planet are billions to one against, yet we seem to have discovered plenty in the last few years. It’s taken over 50 years, but hey, Rome wasn’t built in a day. And, the slim chance of winning our National Lottery is about 14 million to one, but I still buy my ticket every Saturday. As they say: “You have to be in it, to win it”.
NASA realised that rather than look around the night sky haphazardly, better to focus in on a small sample area. Latest technology is far better than that which Sagan had at his disposal. Hence, the new Kepler Telescope. Like it’s Hubble predecessor, The Kepler Discovery Mission 10, works from space, where it’s not hampered by air pollution. It was specifically designed to survey our region of the Milky Way galaxy to discover hundreds of Earth-size and smaller planets in or near the habitable zone. To date it has discovered over one thousand.
The chances of any of these having intelligent life are still remote. If any do have water, the must have ingredient for life, most would probably be simple microbes, algaes and other single-celled organisms. A bit like the Earth would have been 3 and a half billion years ago. Anybody discovering the Earth that far back would have concluded that this planet did not have any intelligent life forms. Other suitable planets could exist where intelligent life forms may once have existed, but became extinct eons earlier.
We may find the right planets, and the signs are promising, but are we at the right time? As Mister Spock might have put it: “It’s life, Jim, but not as we know it”.