Discovery of Dwarf Planet Eris 17 Years Ago Reignites Debate On Reinstating Pluto In the Solar System

NASA researchers found Eris, the solar system's second-largest dwarf planet, on Jan. 5, 2005. This dwarf planet is slightly smaller than Pluto, yet it circles the Sun three times further.

Eris was once supposed to be larger than Pluto, and NASA classified it as the solar system's ninth planet.

The International Astronomical Union (IAU), per Space.com, was not pleased with the addition of Eris to the solar system's roster of planets. Instead, they opted to create the first formal definition of "planet," leaving Eris and Pluto out.

New Horizons Nears July 14 Flyby Of Pluto — IN SPACE - JULY 13: In this handout provided by the National Aeronautics and Space Administration (NASA), Pluto's largest moon Charon is shown from a distance of 289,000 miles (466,000 kilometers) from the Long Range Reconnaissance Imager (LORRI) aboard NASA's New Horizons spacecraft, taken on July 13, and released July 15, 2015. New Horizons passed by Pluto July 14, closing to a distance of about 7,800 miles (12,500 kilometers). The image was combined with color information taken from the craft's Ralph instrument. The 1,050-pound piano sized probe was launched January 19, 2006 aboard an Atlas V rocket from Cape Canaveral, Florida. NASA/APL/SwRI via Getty Images

(Photo: NASA/APL/SwRI via Getty Images)IN SPACE - JULY 13: In this handout provided by the National Aeronautics and Space Administration (NASA), Pluto's largest moon Charon is shown from a distance of 289,000 miles (466,000 kilometers) from the Long Range Reconnaissance Imager (LORRI) aboard NASA's New Horizons spacecraft, taken on July 13, and released July 15, 2015. New Horizons passed by Pluto on July 14, closing to a distance of about 7,800 miles (12,500 kilometers). The image was combined with color information taken from the craft's Ralph instrument. The 1,050-pound piano-sized probe was launched January 19, 2006, aboard an Atlas V rocket from Cape Canaveral, Florida.

Eris Explained

Eris was discovered in 2005 as part of the Palomar Observatory's research of the solar system's outer regions, The Daily Guardian said.

One rotation around our Sun takes 557 Earth years for the frigid minor planet Eris. Eris' orbit sits outside the plane of the Solar System's planets and extends into the Kuiper Belt, an area of frozen debris beyond Neptune's orbit.

Because this dwarf planet is so far from the Sun, its atmosphere compresses and hardens like ice enamel at the surface. Its covering gleams brightly and reflects the same amount of light as newly fallen snow. Surface temperatures are thought to range from -217 to -243 degrees Celsius, according to scientists. As Eris approaches the Sun, its weaker atmosphere will evaporate within a few hundred years, revealing a stony surface that astronomers believe resembles Pluto.

Should Pluto Be Classified As A Planet Because of Eris?

Scientists contending that Pluto should be classed as a planet continue to receive more ammunition in a 15-year-long argument.

A group of experts argues that scientists should raise Pluto and other objects in our solar system to the status of planets. They published the review article, "Moons Are Planets: Scientific Usefulness Versus Cultural Teleology in the Taxonomy of Planetary Science," in the scholarly journal "Icarus."

Since its discovery in 1930, Pluto has been regarded as the ninth planet in our solar system. In 1992, however, astronomers found Pluto's tiny, icy neighbors in the Kuiper Belt. Eris, a celestial body, is one of such neighbors. Whether Eris should be included in the solar system as the 10th planet raged on.

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The International Astronomical Union (IAU) developed new criteria in 2006 that excluded Pluto from being recognized as a planet, relegating it and its neighbors to dwarf planet status.

According to the International Astronomical Union, a planet must be a sphere, orbit the Sun, and have enough gravity to keep other objects out of its orbit. Pluto meets two of the criteria by being spherical and orbiting the Sun.

On the other hand, Neptune's gravity has an impact on Pluto. In addition, the dwarf planet orbits other objects in the Kuiper belt.

The authors of the new paper say that planetary scientists dislike the IAU's definition, preferring to employ a concept of a planet that is essentially geophysical/geological and not constrained by a body's present orbital state.

There is evidence that scientists oppose the IAU's planetary definition, while it is unclear which side has the majority view.

Former NASA Administrator Jim Bridenstine, presenting at the University of Colorado in 2019 (per FOX News), stated he believes Pluto is a planet.

The IAU told FOX Television Stations that it "respects all scientific viewpoints and supports free debate." IAU's scientific decision-making authority is the General Assembly every three years.