1. Largest Dwarf Planet: Eris is the largest known dwarf planet in our solar system, even larger than Pluto. This makes it a significant player in the outer reaches of our solar system.

2. Extremely Elliptical Orbit: Eris has a highly eccentric orbit, meaning it's very elongated. This means it spends most of its time far away from the sun, and then whips around close to it during a small portion of its orbit.

3. Extremely Cold: Due to its distance from the sun, Eris is incredibly cold, with an estimated surface temperature of around -243 degrees Celsius (-405 degrees Fahrenheit).

4. High Reflectivity: Eris reflects a high percentage of light, making it appear bright despite its extreme distance from the sun. This is likely due to its surface being covered in a layer of methane ice.

5. The "Planet" That Changed the Solar System: Eris's discovery in 2005 sparked a debate about the definition of a planet. It was initially considered the tenth planet in our solar system, but ultimately this led to the International Astronomical Union (IAU) redefining what constitutes a planet. Eris, along with Pluto, Ceres, and Makemake, were reclassified as dwarf planets.

6. Moon Dysnomia: Eris has a single moon, named Dysnomia.

7. Uncertain Composition: While scientists believe Eris's surface is covered in methane ice, its interior composition remains a mystery. It might have a rocky core surrounded by a thick layer of ice.

In summary, Eris is a unique and intriguing celestial body that challenges our understanding of the outer solar system and the definition of a planet. It serves as a reminder that there is still much to learn about the vastness of space and the wonders it holds.