Where Can Eris Be Found?

Eris sits about 14.2 billion kilometers from Earth right now — roughly 95 Astronomical Units away. It’s the heaviest dwarf planet we’ve spotted so far, measuring about 2,326 km across with one moon, Dysnomia, tagging along.

Eris hangs out in the Kuiper Belt, way past Neptune’s orbit. That’s a giant, doughnut-shaped zone stuffed with icy leftovers from the solar system’s early days. Eris is technically a Scattered Disk Object, so its orbit is stretched out like a rubber band—sometimes it drifts as far as 97 AU from the Sun. When astronomers spotted it in 2005 and realized it looked bigger than Pluto, the whole “planet” debate blew up. The International Astronomical Union ended up redefining “planet” in 2006, which kicked Pluto down to dwarf-planet status and created the category Eris now calls home.

Eris is basically the Greek goddess of chaos in space — and that name fits perfectly. The dwarf planet’s surface is crazy shiny because it’s wrapped in a super-thin frosting of nitrogen and methane ice, one of the brightest reflectors in the outer solar system. That frost layer is probably less than a millimeter thick, sitting on top of a rocky core. Its lone moon, Dysnomia (named after the daughter of Eris and the spirit of lawlessness), gave astronomers the data they needed to weigh Eris. Turns out Eris is denser—and therefore heavier—than Pluto even though the two look almost the same size.

Don’t bother looking for Eris with your backyard telescope. At 18.7 magnitude, it’s far too faint for naked eyes or binoculars. You’ll need a top-tier professional scope, razor-sharp star charts, and a lot of patience. As for a visit? The New Horizons probe that zipped past Pluto in 2015 took nearly ten years to get there; Eris is even farther away, so a trip would take even longer with today’s rockets. Add in the –240 °C cold and the lack of any real atmosphere, and you can scratch off any hope of finding life as we know it.