Cosmic Scale
Eris
Dwarf planet · 10 billion km from the Sun
How big is Eris?
Eris is about 2,326 km across.
Eris is slightly smaller than Pluto but noticeably heavier. Finding it in 2005 made the question unavoidable: either the Solar System had a tenth planet, or Pluto was something else. Astronomers chose the second answer, and named the newcomer after the goddess of discord.
At a glance
| Diameter | 2,326 km |
|---|---|
| Mass | 1.66 × 10²² kg |
| Diameter compared with Earth | 0.183 × Earth |
| Orbit | 558 years |
| Distance now | About 95 AU from the Sun |
| Moon | Dysnomia |
Good to know
- Its surface is coated in nitrogen and methane frost that may be its atmosphere, frozen out as it moves away from the Sun.
- It reflects 96% of the light that hits it — almost as bright as fresh snow.
- At its most distant it is three times farther from the Sun than Pluto.