"WE must not presume too much upon our own importance," said Benjamin Franklin when told one day in 1757 that the world might collide with Halley's Comet. "There are an infinite number of worlds under the Divine government, and if this one was annihilated it would scarce be missed from the universe."
A question of perennial interest over the years has been whether intelligent life exists on even one of this infinity of other planets. The obvious place to start the search was in our own solar system and in the late 19th century numerous false alarms were sounded as "canals" were discovered on Mars, and various other "signs" of life were noticed on the planet Venus and elsewhere. But as we got to know the solar system better, the likely contenders have been ticked off and eliminated one by one.
That just leaves the universe at large. The problem here is that while a myriad of stars that bear a passing resemblance to our sun can be identified, it has proved impossible until recently to detect which of them, if any may have planets. Last October, however, two Swiss scientists, Mr Michel Mayor and Mr Didier Queloz, caused quite a stir in the astronomical fraternity when they announced that they had discovered a massive planet in orbit around a distant star.
Mayor and Queloz used the "wobbly star" technique. Contrary to our conceptual model of the situation, planets in the solar system or elsewhere do not circle in a simple away around their parent sun instead the whole system revolves around its combined centre of mass. A revolving planet induces a slight displacement of its parent star in the same way as an athlete, preparing to hurl the hammer, has to move in a small circle to counterbalance the weight he whirls around his head. This continual displacement of a planet bearing star appears as a tell tale "wobble" as observed from Earth - a wobble whose rate of oscillation corresponds to a "year" of the orbiting planet.
Using advanced radio astronomy techniques, Mayor and Queloz were able to demonstrate that star 51 Pegasi had such a wobble and, therefore, had a planet. In the following months, other astronomers confirmed their observation and, indeed, discovered that several other stars were also wobbling.
So far, a total of seven distant planets have been spotted and it seems likely that, as techniques improve, more and more of these bodies may be identified in orbit around other stars.
Who knows but that one of them may have just the right regime of temperature to make the existence on it of intelligent life a plausible hypothesis.