Free Astronomy Magazine

DWARF PLANETS med in the innermost regions of the solar system, probably in the gas giants region. What most attracted the attention of the researchers, are however the parameters of the orbit of 2012 VP 113 , a very long ellipse with eccentricity close to 0.7 which takes it from its current 80 AU – coinciding with the perihelion – up to 472 AU (aphelion). This means that 2012 VP 113 needs no less than 4600 years to complete one revolution around the Sun and, as happened with Sed- na, it would have been impossible to spot such a dwarf planet at distances greater than the current ones. In order to have a more precise idea of the context in which 2012 VP 113 is located, it is worth reminding that in the current archi- tecture of our planetary system there are: the rocky planets and the main asteroid belt located between 0.39 and 4.2 AU from the Sun; gas giants between 5 and 30 AU; frozen objects of the Edgeworth-Kuiper belt, which includes Pluto and other dwarf planets, between 30 and 50 AU. Prior to the dis- covery of Sedna it was believed that the planetary system ended more or less there and that no- thing significant existed until the Oort Cloud, a vast reservoir of cometary nuclei, on which the gravitational influence of the Sun is decidedly weak. But then the discovery of Sedna – whose orbit takes it further than all other orbits (76 AU peri- helion, 975 AU aphelion) – and other minor objects (2004 VN 112 and 2010 GB 174 in particular) led astronomers to hypothesize the existence of a new population of icy bodies orbiting in a vast re- gion, at a distance of more than 50 AU (where the gravitational interactions with Neptune are no longer significant) and about 1500 AU; limit beyond which the galactic tides start to become im- portant in the formation proces- ses of planetary bodies. Beyond 1500 AU starts the outer Oort Cloud, which could perhaps ex- tend as far as to 1-2 light years O n the side: images of the 2012 VP 113 discov- ery. The three photographs were taken at intervals of about two hours. The dwarf planet’s movement can be clearly dis- cerned when con- sidering that the arrow is stationary. Below: one of the possible orbits of the super-Earth that according to Trujillo and Shep- pard affects the or- bital motions of 2012 VP 113 and Sedna. [C. Trujillo and S. Sheppard]