Undiscovered planet may be lurking beyond Neptune

Scientists do not know much about the solar system beyond Neptune. But new discoveries about that particular area of space might be hinting at the existence of a previously undiscovered planet in our solar system, according to an article on the Science News website .

In March this year, astronomers Chad Trujillo and Scott Sheppard announced that they discovered a dwarf planet outside the Kuiper belt (the debris field extending outward from the orbit of Neptune).

Designated 2012 VP113, the dwarf planet was 450 km wide and had an elongated orbit, very different from the other planets in our solar system. This orbit shape is similar to Sedna’s, a dwarf planet discovered in 2003.

Trujillo and Sheppard also noted that beyond 150 astronomical units (150 times the distance from the sun to the Earth), the orbits of 10 other previously discovered objects also appeared to be grouped together with the orbits of Sedna and 2012 VP113. All these objects also approached their perihelion (the point closest to the sun) at nearly the same time.

Both Sedna and 2012 VP113 were too far from Neptune to be affected by it, and they were also too far from the Oort cloud, the shell of ice boulders that supposedly envelopes our solar system. This led to speculation that maybe an unseen planet, dubbed Planet X, could be responsible for the orbits of these celestial bodies.

“Whatever put Sedna on its orbit should have put a whole bunch of other subjects out there,” said Megan Schwamb, a planetary scientist at Academia Sinica in Taiwan.

Trujillo and Sheppard estimated that Planet X could be around 2-15 times as large as Earth, and was around 250 AU away from the sun.

Skeptics

Other explanations have been put forward by other scientists.

In a study published in Monthly Notices of the Royal Astronomical Society, physicist brothers Carlos and Raúl de la Fuente Marcos, both from the Complutense University of Madrid, suggested that two planets are actually needed to explain the observed phenomena.

Physicist Lorenzo Iorio from the Ministry of Education, Universities, and Research in Italy said that the planet proposed by Trujillo and Sheppard must be at least twice as far away from the sun as originally predicted. According to him, a planet twice the size of Earth must be at least 500 AU away from the sun.

Other scientists were more skeptical. “The idea’s not crazy,” said David Jewitt, a planetary scientist at the University of California, Los Angeles. “But I think the evidence is slim. The outer solar system can be full of all sorts of unseen and interesting things. But the argument for a massive perturber is a bit puzzling.”

Jewitt noted that 10 out of the 12 objects cross far enough into the Kuiper belt to be influenced by Neptune’s gravity. He added that 12 was too small a sample size to draw any conclusions.

Schwamb puts forth that a passing star could have pulled Sedna and 2012 VP113, distorting their orbits. This scenario becomes more likely if the star is one of our sun’s “siblings,” born from the same nebula. After the star drifted away, the distorted orbits may have frozen in place.

Where did Planet X come from?

Renu Malhotra, a planetary scientist from the University of Arizona, said, “To make a planet the size of the Earth could take longer than the age of the solar system.”

According to Malhotra, the only solution was to steal the planet from somewhere else. Either Uranus or Neptune could have slingshot an Earth-sized planet beyond the Kuiper belt.

Planetary scientist Rodney Gomes of the National Observatory in Rio de Janeiro suggested that Planet X might be “extrasolar.” Many of the sun’s siblings have their own planets, and it’s possible that these stars stole planets from each others’ gravitational pull.

“We haven’t explored all of the solar system yet,” Sheppard said, “so people always want to believe that there’s something else out there.” — Bea Montenegro/DVM, GMA News