Icy dwarf planet in the scattered disc, similar size to Pluto but heavier; its discovery triggered Pluto's reclassification debate.
Dwarf planet: Round, but shares its orbit with other rubble. Every kind of thing there is →
No. No telescope on Earth will show you this one; it is here to be understood, not seen. It is here because it is worth knowing about — and because leaving it out would make the sky look emptier than it is.
Eris is about the same size as Pluto, but heavier. In weight, about 1/360th of Earth -- actually a bit heavier than Pluto! About twice as far as Pluto -- its stretched, tilted orbit carries it out of the Kuiper Belt proper and into the 'scattered disc', flung outward long ago. Sunlight takes 9.4 hours to reach Eris — on average, because that distance changes as it goes round. One Eris year ago, no European ship had yet crossed to the Americas. Its day: ~25.9 hours.
| Across | 2 326 km |
|---|---|
| Distance from the Sun, on average | ~68 AU average, ranging 38 to 98 AU · sunlight takes 9.4 hours |
| Once round its orbit | 559.1 Earth years |
| One day there | 25.9 hours |
Nobody flew a tape measure out there. Every number on this page was worked out from the ground:
Not this one. But the sky over your head is full of ones you can see, and the Planetarium knows which.