The announcement of the discovery of exoplanet Alpha Centauri Bb
on Oct. 16 is a testimony to how far planetary detection
techniques have come over the last few decades.  It brings the
total of confirmed exoplanets -- or "extra-solar planets" -- to
a staggering 825.  However, the search for planets in our own
solar system has subsided since the pioneering days at the end
of the 18th century with the discovery of Uranus and almost one
hundred years later with the identification of Neptune. The idea
of another planet, dubbed 'Planet X,' inspired astronomers to
keep searching for yet another 100 years in a hunt that was full
of twists and turns.    ANALYSIS: Is 'Planet X 2.0' Lurking
Beyond Pluto's Orbit?  The hunt for Planet X began in 1781 when
British astronomer Sir William Herschel was studying stars in
the constellation of Taurus and noticed one star seemed slightly
fuzzy or nebulous in appearance. A few days later it seemed to
have moved position -- he concluded it was a comet. Further
study revealed it wa