The trans-Neptunian dwarf planet Eris, discovered in 2005, comes to opposition in October. Like Pluto, Eris has an eccentric, highly inclined orbit. Its distance from the Sun ranges between 5.7 and 14.6 billion kilometres and it has an orbital period of 557 years. Eris will not be at its closest to the Sun until 2256 and, in 800 years’ time it will for a while be closer to the Sun than Pluto.
Although it is currently a staggering 14.4 billion kilometres (96.4 AU) from the Sun and shines at magnitude +18.7, dwarf planet Eris is actually within the reach of amateur CCD imagers. This distant, deep-frozen little world at the fringes of the Solar System reaches opposition on 16 October, when it is located in northern Cetus, just a hand’s width to the east of Uranus. To find it, point your telescope at RA 01h 41m 59.1s, Dec 03º 15′ 33″.