Properties
Magnitude
18.7
Angular Size
0.034 arcmin
Type: Dwarf Planet
Distance: 67.996 AU
Orbital Period: 203830.0 days
Diameter: 2,326 km
Atmosphere: Possibly transient methane (frozen at aphelion)
Features: Bright methane/nitrogen ice surface (highest albedo of any large solar-system body)
Most massive dwarf planet known; its discovery in 2005 prompted the IAU's 2006 redefinition that demoted Pluto. Has one moon, Dysnomia.
Position & Identifiers
Physical Properties
Diameter
2,326 km
(0.18× Earth)
Mass
1.66e22 kg
Albedo
0.96
(96% reflected)
Temperature
-243°C
Rotation
25.9 hours
Atmosphere
Possibly transient methane (frozen at aphelion)
Surface
Bright methane/nitrogen ice surface (highest albedo of any large solar-system body)
Angular Size
0.0″ (current)
Orbital Properties
Semi-major Axis
67.9960 AU
(10,172.1 million km)
Eccentricity
0.4370
Inclination
43.87°
Orbital Period
558.06 years
Distance
96.453 AU
(13.37 light-hours)
Elongation
18.0°
Near Sun
Observing Tips
Best Months
October
, November
, December
Visibility
Large telescope only
Where to Look
Currently in Cetus (near aphelion ~96 AU)
Notes
Most massive dwarf planet known; its discovery in 2005 prompted the IAU's 2006 redefinition that demoted Pluto. Has one moon, Dysnomia.
Discovery
Discovered by
Mike Brown, Chad Trujillo, David Rabinowitz
Date
2005-01-05
Current Ephemeris
96.453
AU from Earth
14.43B
km
0.0″
Angular Size
18°
Elongation
How easy to spot?
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| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | Imp. | Imp. | Imp. |
| 150 mm Newton 150mm Newt. | Imp. | Imp. | Imp. |
| Celestron C8 (203 mm SCT) C8 203mm | Imp. | Imp. | Imp. |
Easy
Medium
Hard
Very hard
Impossible
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
Out of reach for typical amateur telescopes, even at Bortle 3.
Out of reach
on Seestar S50
Visibility
Set a location in User Settings to see visibility data.
Community Photos (1)
Rendered preview of Eris from the Nightbase orrery, lit from the current Sun direction with the terminator visible.
Credit: Nightbase orrery render.
Skybred Apr 27, 2026
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