• What is Eris?
Eris is the largest dwarf planet that can be found in our Solar System. It is one of the first of the three to be classified as dwarf planets along with Pluto and Ceres. Eris is a huge sphere of rock and ice just like Pluto, with an approximate size of 1,500 miles (2,500 kilometers) in diameter, thus making it 27 percent more massive than Pluto which only has 1,490 miles (2,390 kilometers).

• Where is Eris?
The icy dwarf planet, Eris is the farthest object that orbits the sun; it is even farther than Sedna, another dwarf planet. Eris was about 10 billion miles away from the sun and can be usually found at Kupier Belt region, an icy zone beyond the orbit of Neptune and also a home for Pluto.

• Eris’ Orbit
Eris’ orbit was a strange one unlike Pluto. It is not a circle and has a more elliptical shape. Because of this, the planet won’t be at the nearest distance to the sun until March 2257. The orbit even exceeds the Kuiper Belt, which is the outer edge of the solar system. It is also the reason why Eris will be taking 557 years to revolve around the sun, almost two times longer than Pluto’s.

• Eris’ Satellite
Called by its official name Dysnomia, this moon only takes 15 days to go around the planet, shorter in days than Earth’s moon. The diameter of this satellite was between 100 to 200 kilometers at a distance of approximately 37,370 kilometers. It is believed that this moon was made in a similar way to the process of making our moon. Its name was derived from Eris’ daughter in Greek mythology. Gabrielle, is another name given to Dysnomia. They had found Dysnomia at the Keck Observatory on Mauna Kea at the island of Hawaii.

• The Dwarf Planet’s Age
The dwarf planet Eris is believed to exist the same time as the nearest star on earth, the sun. They are over 4 and a half billion years old.

• The Discovery of Eris
Astronomers Michael Brown, Chad Trujillo, and David Radinowitz was the founders of the Eris the dwarf planet. They found Eris at Palomar Observatory’s Samuel Ochin in January 2005 with its name officially announced on September 13, 2006.

• Xena and Gabrielle
Nicknames of Xena for the dwarf planet Eris and Gabrielle for its satellite came from the TV show “Xena: Warrior Princess” wherein Xena and Gabrielle was one of the main characters in the show.

• The Tenth Planet
The dwarf planet Eris was once a contender for the Solar System’s tenth planet until the year 2006 when International Astronomical Union (IAU) announced a new classification (dwarf planets) for smaller objects in the solar system. Eris was classified as a dwarf planet losing its chance to be called a planet again.

• Observing Eris
Space was being monitored by scientists daily, but due to its long distance from the Earth, Eris has not been made a precise measure of its size; not until an event known as occultation, Eris passed in front of a dim star. This observation informed scientists about its size, shape, and mass.

• Origin of the Name
The name of this planet was adopted from the Greek goddess of discord, Eris, the sister of Ares, and the one who causes the Trojan War. But before the name Eris was finalized, the temporary name was “2003 UB303”. The dwarf planet was named when it was first founded by astronomers on 2015. It also had a nickname, called “Xena”.