Solar System;

With the advances of science and research, many things are very accurately determined nowadays. Not so the number of planets which has last been readjusted in 2006.
Under the geocentric model, the Ancient Greek considered the Sun and Moon to be a planet, while the Earth was the centre of the universe. In the 1600's, the lager moon of Jupiter and Saturn were mistakenly thought to be independent planets. And in the 1800's, some asteroids and dwarf planets were considered to be planets. It was not until 1930 when Pluto has been discovered and become the ninth planet. And it was not until 2006 when it has been reclassified as a dwarf planet.
Good old Pluto is present as is Saturn's ring, both not exactly planets but still visible. Also, while not a planet, the Sun certainly deserves a place as the centre of the solar system.