After ten years of searching, astronomers discovered a second dwarf planet, located far beyond the orbit of Pluto and its cousins in the Kuiper belt.
How Sedna, which was discovered in 2003, and her newfound neighbor, designated VP 2113 as the Center for the Minor Planets, found themselves in such distant orbits from the Sun, remains a mystery.
Sedna rotates 76 times farther away than the earth around the sun, or 76 astronomical units. The farthest point of its 11400-year orbit is located at a distance of 1000 astronomical units.
In the newly discovered VP 2113, the nearest point of the orbit is at a distance of about 80 astronomical units, and the farthest is 452 astronomical units. This little world is about 280 miles (450 kilometers) wide, half the size of Sedna.
No body can explain the modern structure of the solar system with its four rocky planets, four external gas giants, a disk of small ice objects beyond the orbit of Neptune and the rich comets Oloko Oort, some of which are located at a distance of 10,000 astronomical units. “Something else earlier in the history of the solar system should have placed them in these orbits,” says astronomer Megan Schwamb, from Academia Sinica in Taipei, Taiwan.
According to one version, the Sun had a sister star, which, together with it, was formed over a long period of time and under the influence of gravitational forces pushed some of the Oort Cloud bodies inward, creating a new class of objects.
According to the second theory, there was another planet that was not inferior in size to the Earth, which was ejected from the Solar System, carrying objects of the Kuiper Belt into much more distant orbits.
This planet “defector” could leave the limits of the Solar system or can still rotate in a very distant orbit.
Astronomers suspect that there were several planets the size of Earth, formed in the region of the giant planets.
“What exactly happened to these objects is unknown. Perhaps they collided with giant planets and eventually became part of them,” says astronomer Scott Sheppard, from the Carnegie Institution in Washington, DC.
Some computer models show that it was another giant planet that was thrown out of the solar system, attracting objects with which it passed. "The larger the object, the more planets it could push into this region," said Sheppard.
Searches for other Sedna-like objects continue. Sheppard and his colleague Chad Trujillo from the Gemini Observatory in Hawaii are trying to confirm another six potential objects found that year.
It is necessary to use several observatories that will observe for a certain period of at least one year, capable of detecting small dull objects against the background of stars.
“This is a bit of a car view when driving a highway. Objects that are very close move very fast in relation to more distant objects. The technique is to search for objects that move very slowly, relative to background stars The slower they move, the farther they are, ”Trujillo said.
Ultimately, scientists suspect that there are many Sedna-like planets, making them the second largest group of planets that are in a stable orbit around the Sun.