They just discover what a planet is
2006/09/01 Elhuyar Zientzia Iturria: Elhuyar aldizkaria
In recent days there have been bowling: Will our solar system have twelve planets or eight? And what will happen to Pluto?
To answer these questions it was necessary to agree on a definition of planet. And in the end, the decision was made by the International Astronomers Union (at its general assembly held in Prague). A planet is a celestial body that fulfills three conditions: one, orbiting around the Sun; two masses sufficient for its gravity to overcome the forces of rigid bodies, that is, for the form to have a hydrostatic equilibrium (almost circular); and three, the orbit around it is "cleansed".
There are therefore eight planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Pluto, therefore, is out of this list: it will no longer be a planet. Pluto and the other three so-called planets (Ceres, Charon and 2003 UB313) say they are dwarf planets.
