Evidence for a real ninth planet in our Solar System

Image Credit: Caltech/R. Hurt (IPAC); [Diagram created using WorldWide Telescope.]
Joining the list of planets we all know and love in our Solar System: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune, now comes ‘Planet Nine’.

Pluto had once been designated the ninth planet, but was reclassified as a dwarf planet in 2006. 

The new member of the family has not yet been observed directly, rather its presence has been inferred via mathematical modelling and computer simulations by researchers at Caltech. The work was prompted by the behaviour of 13 Kuiper Belt objects which could not previously be explained. 

Planet Nine is calculated to be 10 times the mass of the Earth and on a 10,000 to 20,000 year orbit around the Sun. The simulations reveal the orbit to be anti-aligned, with its closest approach to the Sun at 180 degrees across from all the other objects and known planets.

Read more at http://www.caltech.edu/news/caltech-researchers-find-evidence-real-ninth-planet-49523

Video Credit: Caltech/R. Hurt (IPAC)