Six years ago, in 2005 Eris was discovered, which was an astronomical revolution. Initially it was thought, when it was discovered that its size exceeded that of Pluto, to include it in the list of planets, increasing it to ten. However, the International Astronomical Union decided that, based on their size, neither of them should be called planets, but rather fall into the category of dwarf planets. Right now the number of planets is eight: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune .
Now this new research has surprised all astronomers. Whereas Eris was previously thought to be between 1,200 and 1,400 kilometers in diameter, it has now been found to have a much smaller radius, exactly 1,163 kilometers in diameter.
As detailed by the CSIC researcher belonging to the Andalusian Institute of Astrophysics , José Luis Ortiz, “The new data have come as a surprise, since the estimated radius of Eris has been reduced to about 1,163 kilometers. These calculations are well below the previous ones, which placed it between 1,200 and 1,400 kilometers , and which made Eris the largest object in the Belt of Trans-Neptunian Objects, a region beyond Neptune populated by rocky and icy bodies “
How do they get such accurate data?
The question is obvious: how can it be that the previous calculation range oscillated in 200 kilometers in diameter and is now determined with such precision? For them they have used the concealment of a star by Eris to achieve greater precision. And it is that as Ortiz explains “Pluto has an atmosphere that interferes in the measurements of the diameter. In the case of Eris it has been determined by means of concealment that, if it had an atmosphere, it would be thousands of times less dense than Pluto’s.” The detection was made on November 6 of last year and only three of the 26 telescopes “looking” at Eris at that time captured the occultation.
In addition, Eris has been found to be one of the brightest objects in the Solar System, as the amount of reflected light, known as albedo, exceeds 90 percent. Regarding its composition and orography, astronomers have determined that it is a rocky dwarf planet covered with an ice layer, also explaining that its mass and density are greater than those of Pluto.
“It is the farthest object in the Solar System studied by means of an occultation, which allows its position to be determined with exquisite precision, very valuable for studying its orbital motion,” says the CSIC researcher. Until now it has never been possible to measure solar gravity at such far distances in a reliable way.
