Tau Ceti has been a focus of the science-fictional imagination for decades. Because we knew nothing about exoplanets, because we believed that binary star systems were unlikely to have room for planets in stable orbits, because we believed that life-sustaining planets were not possible around red dwarfs (neither of which are believed to be true now), we focused on Tau Ceti — a G-type yellow sun much like ours (though smaller) less than 12 light years away, with no stellar companion — as the most likely candidate for nearby habitable planets. Later theories discounted the possibility, citing the star’s low metallicity (which reduced the likelihood of rocky planets).
By now you’ve probably heard, though, that Tau Ceti may — may — harbour at least five planets, if what has been found through a new detection method is in fact signal and not noise. If correct, the planets range from two to more than six Earth masses, with orbital periods ranging from 16 to 640 days. At least one of the planets falls within the star’s likely habitable zone. Article, press release.
It’s fuel for the imagination, like Alpha Centauri’s planet, and the fact that Tau Ceti is both visible to the naked eye (magnitude 3.5, easy but not particularly bright) and visible from the northern hemisphere doesn’t hurt. I’ve seen it, and wondered, myself.