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Are we alone?

Tom Feilden | 08:09 UK time, Thursday, 5 March 2009

Just how special is planet earth?

It's a question that's been asked since people first raised their eyes to contemplate the stars, one which touches on the most profound issue of existence: are we alone in the universe?

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It's a question NASA's Kepler Space Telescope - which blasts off from Cape Canaveral tomorrow - hopes to answer.

It's the space agency's first mission capable of finding earth-like rocky planets around distant stars. For the next three-and-a-half years Kepler will stare, unblinking, at a small patch of the Galaxy (actually incorporating some 100,000 stars between Cygnus and Lyra) waiting for the tell-tale dip in brightness as orbiting planets pass in front of them.

Bill Borucki, the principal Investigator on Kepler at NASA's Ames Research Centre, hopes to find hundreds of earth-like planets, and dozens in the habitable or "Goldilocks" zone, that's neither too hot nor too cold to support life.

"Although Kepler will not find ET we are hoping to find ET's home," he says.

If that sounds too good to be true, others are even more optimistic. According to the author of Crowded Universe:The Search for Living Planets, Alan Boss argues that earth-like planets may be the norm rather than the exception.

Extrapolating from the data we already have from ground-based telescopes, and combining that with what we know about the processes of planetary formation, Boss comes up with a figure of 10,000 billion billion earth-like rocky planets in the observable universe.

It has to be said that few at NASA are quite as optimistic as Alan Boss. But even if the Kepler Space Telescope only spots one tiny pale blue dot spinning round a distant star, that will still be pretty exciting.


  • Comment number 1.

    All very interesting, but those who hope to contact alien civilisations should not get too excited. There is a reducing factor, which might be called "Temporal Simultaneity". To communicate, two civilisation have to be technologically active in the same period of time.

    The duration of human beings in relation to earth time has been likened to the thickness of a piece of cigarette paper placed on the topmost railing of the Eiffel Tower, earth time being the Eiffel tower, human history being the paper.

    The search for extraterrestrial intelligence assumes that two pieces of paper exist at exactly the same height, but the planetary towers on which we stand are in fact of hugely different temporal dimensions. Our Sun is a relative late-comer in the family of stars. Civilisations may have appeared on other solar systems in other star generations, but they may not still be around now.
    If a civilisation capable of sending electromagnetic signals continues for hundreds of thousands of years, the paper becomes a little thicker and the likelihood that it will exist simultaneously with another transmitting/receiving civilisation is increased. If however, our civilisation destroys itself through nuclear war or as a result of uncontrolled releases of greenhouse gases and other erosions of our life support system, and if other civilisations have the same proclivities, then the probability of two competent civilisations coinciding in time and making contact with each other becomes vanishingly small.
    I take no pleasure in putting this thought forward, but just suggest that it is something that we have to take into account. And maybe it will provide some further small motivation to abolish WMDs and decarbonise our economy.

  • Comment number 2.


    Just how special is planet earth?

    To answer your question....It is very special, planet earth....

    ~Dennis Junior~

  • Comment number 3.

    There's billions of stars out there in the galaxy so of course we'll detect earth-like planets as our ability to see into the distance improves. But the fact is that our solar system does lie in a galactic backwater and the distances involved getting to, well, anywhere, seem at present overwhelming. Maybe in the future mankind will crack "time travel" and then we'll stand half a chance of communicating with other life in the galaxy. Until then we'll likely always be on our own.


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