Planets beyond Neptune
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Following the discovery of the planet Neptune in 1846, there was considerable speculation that another planet might exist beyond its orbit. The search began in the mid-19th century and continued at th
Percival Lowell, originator of the Planet X hypothesis
Jacques Babinet, an early proponent of a trans-Neptunian planet
Clyde William Tombaugh
Discovery image of Charon
Eris (dwarf planet)
Videos
Eris is the most massive and second-largest-known dwarf planet in the Solar System. It is a trans-Neptunian object in the scattered disk and has a high-eccentricity orbit. Eris was discovered in Janua
Planets beyond Neptune
…were initially described in the media as "new planets". In 2005, astronomer Mike Brown and his team announced the discovery of 2003 UB313 (later named Eris after the Greek goddess of discord and strife), a trans-Neptunian object then thought to be just barely larger than Pluto. Soon afterwards, a NASA Jet…
Low-resolution image of Eris and Dysnomia as imaged by the James Webb Space Telescope's NIRCam on 23 August 2024
Eris and its moon Dysnomia imaged by Hubble Space Telescope on August 30, 2006. Dysnomia's orbit around Eris labeled.
Illustration of the stellar occultation by Eris in November 2010. The resulting occultation chords project a circular silhouette for Eris, giving a spherical diameter of 2,326 km (1,445 mi).
Eris as taken by the Hubble Space Telescope. This image is one of the clearer shots of Eris.