Eris is too distant even for the largest telescopes to be solved on a disc. The concept of this artist shows the best hypothesis of astronomers on how the disnomia of the moon occur. Credit: NASA/ESA/STSCI
At eight billion miles (14 billion kilometers) from the earth, at the shade of the Solar System, there is a strange planet in size of a world that emerged unexpectedly from the darkness 20 years ago. Called for the capricious Greek goddess of Discord, Eris who has without problems would undoubtedly be happy that his hemoninth celestial homonymous caused the quarrel even targeted for even the mild, since his discovery caused the nature of what constitutes a “planet” To breed his controversial head.
With a size of 18.7, Eris is currently located in the southern constellation Cetus La Balena, barely resolved even from the largest telescopes in the world. Due to its vast distance-circle 95,6 astronomical units (au; 1 au is the average distance of the land of the earth)-its slow progress apparent through the sky make it notoriously difficult to identify.
At the distance of Eris, the sun appears as a small star in the carbon-buio sky, its light takes 13 hours to cross the space with each other and weakly illuminate a glittering surface of methane and nitrogen. Eris is three times more distant than Pluto. And his relationship with Pluto – a world relegated since 2006 from the ninth planet of the Solar System to a humble dwarf planet, largely due to the discovery of Eris – remains controversial today.
A distant discovery
In 2001, the astronomers of the Palomar Observatory in California began to systematically look for objects of the size of a planet beyond Neptune. This process that takes time has targeted small pockets of the sky, using powerful imaging software to identify everything that moved in the starry background. To limit the number of false positive data yields due to the resolution of the images, the software has excluded anything that moves more slowly than 1.5 arcaseconds per hour.
“Things like Eris were exactly what we were looking for when we started this survey in 2001,” says Mike Brown of the California Institute of Technology, who co-scope with Chad Trujillo, then of the Gemini Observatory, and David Rabinowitz of Yale University . “At that time, nothing had ever been found over 60 UA, so we tuned the survey to focus on this area.”
But an ironic consequence was that the images of Eris with a slow movement, taken by the Brown team with the 48 -inch Samuel Oschin telescope (1.2 meters) in Palomar on October 21, 2003, they slipped completely through the network, descending from under the cutting of speed.
In the months that followed, several new trans-Neptuniani-Corpi objects were discovered whose orbits have an average distance beyond that of Neptune-Furuno Discoveries: red colors in November 2003 and Humea in the shape of a ellipsoid in December 2004. The orbit 11,400 years of Sedna transports to an AFELION (its point farthest from the sun) well beyond eliopause, the region near the outskirts of the Solar System where the Sun gives way gravitational influence on the interstellar medium.
At the time of his discovery, Sedna was at 90 UA – 8.3 billion of miles (13.3 billion of km) from the sun, three times more distant than Neptune. And significantly, he moved to a miserable 1.75 arcasecondi per hour. This prompted the Brown team to re -establish their older data with lower limits on the angular movement, therefore scrupulously orders the images previously excluded by eye.
“When we found Sedna in 2003 to almost 90 UA and just at the limit of our software, we wondered if we could have lost something even further away,” recalls Brown. “It took months of further work and processing, until Eris suddenly comes out of the data! In the end, it was the only extra object that we found from all portion – but it’s worth it! “
The Rianalisi del Team has finally identified Eris on January 5, 2005. At that time, he was simply called UB of 2003313. Brown excited his wife, Diane with excitement with the news: “I found a planet! “
But his words were threateningly propitious, since the circumstances that take place on earth quickly exceeded the discovery.
More planets?
The first observations have hinted that Eris could be larger than Pluto, whose dimensions remained uncertain until the New Horizons spatial vehicle flew beyond July 2015.
But it is larger or smaller than Pluto, the hopes that in Eris can also be granted to the planetary state. For years, astronomers had discussed the Pluto planet a lot. Our ninth planet was smaller than any other planet, but transported profound cultural connotations, which approached the generations that had grown up by reciting the same mnemonic sun system in class and accepted it universally as a ninth planet.
That long-standing popular belief was shot in the head with the discoveries of Humea, Sedna, Eris e-chopse months later Eris-Makemake in March 2005, forcing the hand of the astronomical community. In August 2006, the International Astronomical Union (IAU) formally defined a “planet” as an object that surrounds the sun, large enough and gravitationally massive to reach a spherical shape and has eliminated its region of space.
Under that definition, the new discoveries were not up to this third point, since no one had eliminated their respective celestial neighborhoods. But neither of them had Pluto. On September 6, 2006, Pluto and the others were formally reassembled not as planets but as “dwarf planets” – objects in orbit in orbit in the sun that could reach sphericality but were gravitatedly unable to dominate their surroundings.
“We knew that second that we found it [Eris] That our concept of Solar System should have changed, “says Brown.” We should add new planets or steal one. I would have foreseen the first, but even if this means that I had lost the possibility of being called the discoverer of some new planets, they are Lieto that astronomers had the courage to make the right choice and realize that Pluto should never have been called to the planet.
What’s in a name?
September 13, 2006, 2003 UB313 It was formally called Eris. But this had not been the original choice. An unofficial name used by Brown’s team was Xena, in honor of the titular person in the television show Xena: Warrior Princess – which also began with an X, for what could have been the tenth planet.
“We immediately called Xena, just like one of our names of internal code,” says Brown. “But when the final decision IAU came out, we decided to look for something in Greek or in Roman mythology to honor the fact that Xena had been something like a real planet for a happy new year. It is not surprising that almost everything has been taken by various anonymous asteroids over the years. “
Popular suggestions collected in a survey from New scientist He varied from Persephone to Pax, Galileo in Xena, Rupert in Nibiru and Cerberus in Loki. The results of the survey even included the “Bob” comically floated as an option, its originator made a licking that was easily pronounced, not offensive and “I think Uranus needs a break, right?”
“But everyone seemed to have avoided the goddess of discord and conflict”, whose Greek name was Eris, recalls Brown. “As soon as we saw it, we realized [it] It was perfect. “Just like the goddess inviting for the conflict of ancient Greece, the celestial Eris had pushed the nest of debate of his hornet both in the astronomical community and among the wider audience.
It turns out that Eris is slightly smaller than Pluto, with an equatorial diameter of 1,445 miles (2,326 km) and a surface approximately equivalent to South America. But Eris is about 27 % more than Pluto, probably due to a more dense and rocky interior.
A small moon, called Dysnomia after Eris’s mythological daughter and the goddess of illegality, was discovered in September 2005 by Brown’s team to the Keck observatory in Mauna Kea in Hawaii. Dark as Carbone, a third of the size of Eris and frozen of nature, orbit disnomomy every 16 days at a distance of 23,200 miles (37,300 km).
The simple white facade of Eris reflects about 96 percent of the sunlight, making it one of the brightest surfaces of the sun system. His highly eccentric orbit brings him around the sun every 559 years, bringing him close to 37.9 UA (3.5 billion miles [5.6 billion km]) and bringing it up to 97.5 UA (9.1 billion miles [15 billion km]). The surface temperatures hover around 42 Kelvins – about –384 degrees Fahrenheit (–231 degrees Celsius).
His omnipresent brightness is only combined with the Encelado of the Ice Moon of Saturn, but Brown does not believe that the cryovolcanism or Geyser are necessarily responsible. “Eris is cold enough that his atmosphere will be condensed on the surface and I think it’s really everything that is happening,” he says. “Presumably while Eris approaches the sun, the sublime frosts and the surface will darken.”
Having exceeded his most recent AFELION in 1977, Eris will reach Perielione in 2257. The plans for a Flyby mission are taken into consideration, with the most ideal launch opportunities in 2032 and 2044. If such a mission were to take place, the vehicle Space could reach Eris approximately 25 years after the launch.
And surely they would follow new discoveries.
Related: The planet nine exists?
