Our nearest star has a planet:
I still remember the times when the question of our loneliness in the universe was encircled by puzzling questions on the same train of thought about the solar system and its uniqueness. We saw many stars, as we always did, but no other planets other than the one in the solar system. That made us think we are a "special" one, and being (so far, at least) the only one with life in our solar system made us even more pretentious on being unique. There was no clear answer for why apparently only our sun had planets. There are trillions of sun in a galaxy and trillion of galaxies in the universe. Why didn't we see more planets around us? That made us feel astronomically lonely and misunderstood.
It was no more that two decades ago when the first confirmed planet outside the solar system was discovered. Since then, more than 800 extrasolar planets have been discovered. The planets were there, but our technology wasn't good enough to see them, next to the luminosity of stars, often many orders of magnitude brighter than ours. The science of looking for exoplantes has increasingly become a very hot topic in astronomy. Techniques are becoming finer and astonishingly precise.
This month, it has been announced that even our closest neighbor, Alpha Centauri, just 4.3 light years distant, has a planet. And it is a small and rocky one, even if too close to the star to be habitable and to even host water in liquid form. Nonetheless, it is an amazing discovery. Alpha Centauri - being the closest star - was heavily studied and it was the natural first place to look for another planet. Yet it was never found, because its planet is very close to the star and moving quickly.
This news not only is amazing for sci-fi lovers, for which Alpha Centauri has always been target of the creative fantasy of films and books writers, and still not only from a philosophical point of view, giving hints toward a more planet-populated universe, but also for scientists. The technique to make the discovery certain had to deal with measurements with precisions on the scales of half-a-meter per second. That is slower than walking speed. And remember that those measurements are from a source 40 millions of millions kilometers away from us.
From the uncertainty of having other planets at all in the universe to the certainty of having one on our closest star, it only took twenty years. How long will it take to discover the first one in the habitable zone and with life on it?
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