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Our sun is a typical star, right? Nope, you couldn’t be more wrong, but your opinion is entirely understandable, since that is how it is often portrayed. In fact our sun is more massive than 95% of all stars. Stars without our sun’s mass are incapable of holding habitable planets in orbit, immediately eliminating them from contention for the possibility of sentient life.

So what about the 5% of stars that have our sun’s mass, or greater? Surely they could hold planets? True, and in fact a number of planets have been detected around stars more massive than our own. But their size is their nemesis. More massive stars are hotter and radiate substantially more ultraviolet light than our sun. Ultraviolet light breaks the bonds of biological molecules and UV light is itself disastrous for the formation of an atmosphere. Our sun emits less than 10% of its energy as UV light, making our sun very rare indeed.

But it is not only our sun’s mass and the nature of the radiation that it emits rare, but so too is its stability. Unlike many stars, our sun has singularity. Many stars are binary, and the nearest ‘one’ to us, Alpha Centauri, is in fact three stars in close proximity, making life impossible. Nor is our sun variable, as most stars are, emitting a change in the amount of radiation produced over time. Our sun is remarkably dull in this department, with almost a negligible variation in radiation emitted. Apparently this radiation is not only stable, it has been consistently so for a remarkably long period of time, perhaps as much as 5 billion years and will remain so long into the future, as much as another 5 billion by some estimates. These factors: distance from the cataclysmic center of the galaxy,  high mass, consistent radiation, low incidence of UV radiation, singularity and longevity make our sun almost unique in the galaxy.

Speculating about life around other suns is fun, and I love a good science fiction story as much (and probably more) than most. I will see the new Star Trek movie as soon as it hits the screens in KL. Aside from driving movies and science fiction novels, keeping the notion of extra-terrestial life alive is also a good funding strategy for NASA and other science agencies that depend on public acceptance for their financing. But beware of public opinion on this subject. It can be manipulated for purposes that serve the needs of the few, at the expense of the understanding of many. The Earth is rare, and perhaps unique.

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