Images: Dwarf Planet Eris, Pluto's Cosmic Twin

Artist's Impression of Dwarf Planet Eris

This artist's impression shows the distant dwarf planet Eris. New observations have shown that Eris is smaller than previously thought and almost exactly the same size as Pluto. Eris is extremely reflective and its surface is probably covered in frost formed from the frozen remains of its atmosphere.

Occultation of Dwarf Planet Eris in November 2010

This diagram shows the path of a faint star during the occultation of the dwarf planet Eris in November 2010. Two sites in South America saw the faint star briefly disappear as its light was blocked by Eris and another recorded no change in brightness. Studies of where the event was seen, and for how long, have allowed astronomers to measure the size of Eris accurately for the first time. Surprisingly, they find it to be almost exactly the same size as Pluto and that it has a very reflective surface.

Artist’s Impression of the Dwarf Planet Eris and Moon Dysnomia

This artist's impression shows the distant dwarf planet Eris in the distance with its moon Dysmonia in the foreground. New observations have shown that Eris is smaller than previously thought and almost exactly the same size as Pluto. Eris is extremely reflective and its surface is probably covered in frost formed from the frozen remains of its atmosphere. Dysnomia appears to be a darker and less reflective body.

Dwarf Planet Eris' Shadow Path During November 2010 Occultation

This artist’s impression shows the shadow of the dwarf planet Eris as it was crossing the Earth during the occultation during November 2010. The regions along the path saw a faint star briefly disappear as its light was blocked by Eris. Studies of where the event was seen, and for how long, have allowed astronomers to measure the size of Eris accurately for the first time. Surprisingly, they find it to be almost exactly the same size as Pluto and that it has a very reflective surface.

Artist's Impression of the Dwarf Planet Eris

This artist's impression shows the distant dwarf planet Eris. New observations have shown that Eris is smaller than previously thought and almost exactly the same size as Pluto. Eris is extremely reflective and its surface is probably covered in frost formed from the frozen remains of its atmosphere. The distant Sun appears to the upper right and both Eris and its moon Dysnomia (center) appear as crescents.

The Man Who Killed Pluto: Q & A with Astronomer Mike Brown

Caltech researcher Mike Brown led the team that found the dwarf planet Eris in 2005. The discovery helped spur astronomers to rethink the definition of "planet," and ultimately strip Pluto of its planethood.

Eris: Rival to Pluto

Artist's rendering of Eris, announced in July 2005 by Mike Brown of Caltech. It is more massive than Pluto. The sun is in the background.

Solar System to Scale (Infographic)

A graphical representation of our solar system to scale - see how far the planets are from the sun in astronomical units.