Eris: The Icy Outpost of the Solar System

The Eris | A series on our Planet Eris By Academic Block

In the vast expanse of our solar system, beyond the orbit of Neptune, lies a celestial enigma that has intrigued astronomers and stargazers alike: the Eris, a Dwarf Planet. This diminutive world, shrouded in mystery, offers a window into the outer reaches of our cosmic neighborhood. In this article, we’ll delve into the fascinating realm of Eris, shedding light on its facts, characteristics, size and composition, orbit and distance, and much more. So buckle up, and let’s embark on an interplanetary journey like no other.

Eris Facts and Characteristics

Eris, formally known as 136199 Eris, stands as one of the largest known Trans-Neptunian Objects (TNOs), a category of celestial bodies that reside in the Kuiper Belt. This icy realm, located beyond Neptune, is home to a host of intriguing entities. Eris, with its diameter measuring around 2,326 kilometers (about 1,445 miles), is comparable in size to Pluto, which sparked a significant debate about its planetary status. Its mass is approximately 1.66 x 1022 kilograms. This value is derived from observations of Eris’s gravitational effects on its moon Dysnomia and other nearby objects.

The journey around the Sun for Eris is a slow dance. Its highly elliptical orbit brings it as close as 5.7 billion kilometers (3.5 billion miles) and takes it as far as 14.6 billion kilometers (9.1 billion miles). This elongated orbit is a testament to the gravitational influences of distant celestial bodies, reminding us of the intricate choreography that governs the celestial ballet of our solar system. Due to this long orbital period and its slow movement along its elliptical path, it takes Eris about 557 Earth years to complete one orbit around the Sun.

When Eris is at its closest approach (perihelion) to the Sun, it experiences its relatively “warmest” temperatures, although “warm” is a relative term here. During perihelion, Eris reach temperatures of approximately -217 degrees Celsius (-359 degrees Fahrenheit). At its farthest point (aphelion) from the Sun, Eris is subjected to extremely frigid conditions. Temperatures at aphelion can drop to around -243 degrees Celsius (-405 degrees Fahrenheit).

Eris Composition 

Eris’s composition is a cosmic puzzle, as it is primarily composed of rock and ice. Its surface, composed of a mixture of methane and nitrogen ice, gives it a distinct reddish hue when observed from afar. The presence of methane hints at potential processes shaping its surface, similar to those on Pluto. Eris’s home, the Kuiper Belt, is a region teeming with icy bodies that hold clues to the early history of our solar system. Studying Eris and its neighboring objects provides valuable insights into the conditions that prevailed during the solar system’s formation.

Eris Surface Features and Scientific Research 

Observations of Eris’s surface have revealed intriguing features, including regions of differing reflectivity that suggest variations in surface composition. The presence of methane and nitrogen ice hints at possible cryovolcanic processes at play, shaping the surface over cosmic timescales. These surface features stand as a testament to the intricate geological processes occurring on this distant world. It’s important to note that our knowledge of Eris’s surface is still limited compared to more well-studied bodies in our solar system.

Eris Discovery and its Moon 

Eris was discovered in 2005 by a team led by astronomer Mike Brown at the Palomar Observatory in California. This discovery not only expanded our understanding of the outer solar system but also sparked a significant debate regarding the classification of Pluto as a planet. Eris is accompanied by a single moon, Dysnomia, named after the daughter of Eris in Greek mythology.

Eris vs Pluto: The Great Debate 

The discovery of Eris and its comparable size to Pluto fueled a debate within the astronomical community. The debate culminated in 2006 when the International Astronomical Union (IAU) redefined the criteria for classifying celestial bodies, reclassifying Pluto as a “dwarf planet.” This decision paved the way for a deeper understanding of the diversity of objects residing in the outer solar system, including Eris.

Race to Eris: Space Missions from Around the World

Eris has captured the attention of scientists and space agencies around the world. Its position in the Kuiper Belt, a region beyond Neptune filled with icy bodies, has led to the formulation of ambitious missions aimed at uncovering the secrets held by this distant celestial neighbor. Here is the list of various missions to Eris from different countries and organizations.

New Horizons Mission (NASA, USA)

One of the most iconic missions in recent history, NASA’s New Horizons spacecraft, launched in 2006, achieved global recognition for its close flyby of Pluto in 2015. But did you know that this mission also set its sights on Eris? Although Eris was not its primary target, New Horizons conducted observations of Eris in 2010 as it passed through the outer solar system. These observations contributed valuable data to our understanding of this distant dwarf planet.

ESA’s Cosmic Vision Proposal (ESA, Europe)

The European Space Agency (ESA) has long been considering various missions as part of its Cosmic Vision program. Among these proposals was a mission concept known as the EChO (Exoplanet Characterization Observatory), which aimed to study exoplanet atmospheres. While EChO didn’t specifically target Eris, it was designed to study a wide range of celestial bodies, including those in the Kuiper Belt.

Potential Future Missions

While no dedicated missions have been launched solely to study Eris, the ever-evolving landscape of space exploration holds promise for potential future endeavors. As technology advances and our understanding of the outer solar system deepens, the idea of a dedicated mission to Eris becomes increasingly feasible. These missions could involve orbiters, landers, or flyby missions designed to closely study Eris’s composition, surface features, and interactions with its moon Dysnomia.

Eris in Mythology: A Tapestry of Cosmic Discord

Throughout human history, cultures around the world have woven intricate tales to explain the mysteries of the cosmos, often using celestial bodies as a canvas for their myths. Eris, located in the Kuiper Belt, has not escaped the realm of mythology. From Greek and Roman narratives and beyond, let’s explore the diverse mythological threads that connect Eris to the human imagination.

Greek Mythology: Discord’s Mischievous Muse

In ancient Greek mythology, Eris personified discord, strife, and chaos. She was often depicted as a troublemaker, sowing the seeds of discord among gods and mortals alike. Eris played a pivotal role in the myth of the Apple of Discord, a golden apple inscribed with the words “For the fairest.” This apple ignited a rivalry among the goddesses Hera, Athena, and Aphrodite, leading to the famous Judgment of Paris. Paris, a mortal prince, was tasked with awarding the apple to the most beautiful goddess. His decision set off a chain of events that ultimately sparked the Trojan War.

Eris’s role as the instigator of conflict and chaos in Greek mythology draws parallels to the celestial realm, where her namesake, the Eris, resides amidst the icy bodies of the Kuiper Belt.

Roman Mythology: Discordia’s Influence

In Roman mythology, the figure Discordia corresponds to the Greek goddess Eris. Discordia was often invoked in rituals and ceremonies, particularly those related to discord and chaos. She embodied the unpredictable nature of the universe and the complexities of human interactions. In a cosmic context, the Eris unpredictable orbit and interactions with other celestial bodies echo these themes of variability and unpredictability.

The intertwining of Eris with various mythologies invites us to explore the intersections of science, culture, and imagination. While these myths may not directly explain the scientific characteristics of the Eris, they offer insights into how humans have sought to make sense of the cosmos throughout history. Mythological narratives also highlight the enduring human fascination with the universe and its mysteries.


This article has taken you on a journey through the intriguing landscape of the Eris the Dwarf Planet. Based on thoroughly researched scientific literature, the information provided here is not only interesting but also easily understandable for readers of all ages. By learning about Eris’s facts, characteristics, and place in the solar system, Academic Block hope that you’ve gained insight into the ongoing dialogue in astronomy and planetary science. Please provide your comments and suggestions, this will help us in improving this article. Thanks for reading.

Interesting facts on the Eris
  1. Discovery and Naming: Eris was discovered in 2005 by astronomer Mike Brown and his team at the Palomar Observatory. It was initially nicknamed “Xena” after the TV show warrior princess, but its official name, Eris, was later chosen in reference to the Greek goddess of strife and discord.
  2. Size and Comparison: Eris is one of the largest known dwarf planets in our solar system, with a diameter of about 2,326 kilometers (1,445 miles).
  3. Eccentric Orbit: Eris has a highly eccentric and elongated orbit around the Sun, which brings it as close as 5.7 billion kilometers (3.5 billion miles) and takes it as far as 14.6 billion kilometers (9.1 billion miles) away.
  4. Moon Companion: Eris has one known moon named Dysnomia, named after the daughter of Eris in Greek mythology. Dysnomia is significantly smaller than Eris and is believed to have been created from debris resulting from a collision.
  5. Surface Composition: Eris’s surface is composed of a mixture of rock and ice, primarily methane and nitrogen ice. This combination gives it a reddish hue when observed from a distance.
  6. Kuiper Belt Dweller: Eris resides in the Kuiper Belt, a region beyond Neptune filled with icy bodies. It is part of a group of objects known as Trans-Neptunian Objects (TNOs) that share this distant region of the solar system.
  7. The Great Debate: Eris’s discovery sparked a reevaluation of Pluto’s status as a planet. It led to the redefinition of the criteria for classifying celestial bodies, ultimately leading to Pluto’s reclassification as a “dwarf planet.”
  8. Slow Rotation: Eris rotates on its axis relatively slowly, taking about 25.9 hours to complete a full rotation.
  9. Cryovolcanism Hypothesis: Some scientists speculate that Eris might exhibit cryovolcanism, a process where icy materials erupt like molten lava on Earth. This could explain its diverse surface features.
  10. Distant and Cold: Eris is one of the coldest objects in our solar system due to its distance from the Sun. Average temperatures on its surface are estimated to be around -230 degrees Celsius (-382 degrees Fahrenheit).
Related academic references in terms of books and published articles on Eris
  • Carroll, B. W., & Ostlie, D. A. (2006). An Introduction to Modern Astrophysics. Pearson Education.
  • Beatty, J. K., Petersen, C. C., & Chaikin, A. (2006). The New Solar System. Cambridge University Press.
  • Stern, S. A., & Tholen, D. J. (2018). Our Universe: The Thrill of Extragalactic Exploration. Cambridge University Press.
Research Articles:
  • Brown, M. E., van Dam, M. A., Bouchez, A. H., et al. (2006). Satellites of the largest Kuiper belt objects. The Astronomical Journal, 132(1), 200-208.
  • Ragozzine, D., Brown, M. E., & Schlichting, H. E. (2009). The Mathematics of Kuiper Belt Binaries. The Astronomical Journal, 137(6), 4766-4776.
  • Thirouin, A., Ortiz, J. L., Duffard, R., et al. (2010). Short-term variability of 2003 AZ84. Astronomy & Astrophysics, 522, A93.
Web reference on the Eris
  1. NASA Science: Eris Website: Description: NASA’s official page on Eris provides an overview of the dwarf planet, including key facts, images, and links to related resources.
  2. The Planetary Society: Eris Website: Description: The Planetary Society offers information about Eris, including its discovery, characteristics, and its role in the solar system.
  3. European Southern Observatory (ESO): Dwarf Planet Eris Confirms Pluto’s Demotion Website: Description: This ESO press release discusses the confirmation of Pluto’s reclassification as a dwarf planet and its relationship with Eris.
  4. Astrobiology Magazine: Eris: The Solar System’s Largest Dwarf Planet Website: Description: Astrobiology Magazine offers an article exploring Eris’s characteristics, discovery, and its significance in our understanding of the solar system.
  5. Space Telescope Science Institute: Eris and Dysnomia Website: Description: This Hubble Space Telescope news release discusses the discovery of Eris’s moon Dysnomia and its implications.
  6. University of California, Los Angeles (UCLA): Eris Website: Description: Dr. Mike Brown’s website provides information about Eris, including its discovery and related research.
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