Historic and revolutionary change in the world of science has occured. Astronomers have stripped Pluto of its planet status which means that Pluto is no longer the 9th planet of our solar system. WHEN ? ANSWER
: 24 th OF AUGUST 2006 this historic decision was announced to the world BY WHOM ? ANSWER:
About 2,500 scientists meeting in Prague have adopted historic new guidelines that see the small, distant world demoted to a secondary category. WHY? ANSWER:
The researchers said Pluto failed to dominate its orbit around the Sun in the same way as the other planets. Pluto's status has been contested for many years. It is further away and considerably smaller than the eight other "traditional" planets in our Solar System. At just 2,360km (1,467 miles) across, Pluto is smaller even than some moons in the Solar System.Its orbit around the Sun is also highly tilted compared with the plane of the big planets. In addition, since the early 1990s, astronomers have found several objects of comparable size to Pluto in an outer region of the Solar System called the Kuiper Belt. Some astronomers have long argued that Pluto would be better categorised alongside this population of small, icy worlds. The critical blow for Pluto came with the discovery three years ago of an object currently designated 2003 UB313. After being measured with the Hubble Space Telescope, it was shown to be some 3,000km (1,864 miles) in diameter: it is bigger than Pluto. 2003 UB313 will now join Pluto in the dwarf category, along with the biggest asteroid in the Solar System, Ceres.
Named after the god of the underworld in Roman mythology, Pluto orbits the Sun at an average distance of 5.9 billion kilometres (3.7 billion miles) taking 247.9 Earth years to complete a single circuit of the Sun. An unmanned US spacecraft, New Horizons, is due to fly by Pluto and the Kuiper Belt in 2015.