The mystery of the ninth planet: scientists are getting closer to discovery

Far beyond the eight planets of the solar system, even behind Pluto and miniature dwarf planets can hide a significant new world, called the "ninth planet". Few discoveries can be as sensational as another planet orbiting the Sun, so this topic has served as the Holy Grail for astronomers — and for several centuries this discovery has been made only a few times. So far no one knows where this ephemeral world can be located, or even whether it really exists. But in the race for discovery, the researchers narrow the search space based on the influence of a celestial body on the solar system, and the section of space where the planet should be looked for has decreased by about half compared to the state it was a few months ago. At a meeting of the American Astronomical Society of Planetary Sciences and the European Congress of Planetary Sciences, scientists described in detail their latest achievements in this area.

In January, astrophysics at the California Institute of Technology Konstantin Batygin and Michael Brown demonstrated evidence of the existence of a large undiscovered ninth planet. From their computer models, it follows that the gravitational effect of this planet may explain the strange, inclined orbits of several objects from the Kuiper belt - a set of ice objects inhabiting the far reaches of the solar system. Scientists are fighting for the right to be the first to discover the ninth planet using the largest telescopes on Earth, such as the Subaru telescope in Hawaii.

The work of Batygin and Brown set limits on the possible mass of the planet and the location of its orbit - where previous observations could have missed it. According to their calculations, its mass is from 5 to 20 Earth - which is critical for understanding the approximate size of the object sought. They also believe that its orbit is inclined by 30 degrees to the plane of the solar system - a relatively thin and flat zone in which eight main planets rotate. They also assume that now the planet is farthest from the Sun, in the northern hemisphere of the sky, and the radius of its elongated orbit is on average in the range from 380 to 980 AU.
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But these estimates still capture a sky sector of about 1,500 square degrees, as astronomer Scott Sheppard of the Carnegie Institute of Science, along with astronomer Chadwick Trujillo, suggested the existence of a ninth planet in 2014, says. For comparison, the full moon occupies 0.2 square degrees of the night sky. The sky coverage described by Sheppard corresponds to approximately 20 night observations from the Subaru telescope, “and getting access to it for seven nights a year, it turns out, you have to wait three years - and that if there is no rain,” Sheppard says.

The strategy of the race is to reduce the search area by eliminating theoretical possibilities. In a yet unpublished collection of 100 high-resolution computer simulations, according to Batygin, he and Brown reduced the search for the ninth planet to a piece of sky 600-800 square degrees in size. First, they built a model for the development of the Solar System over 4 billion years, concentrating on how the gravity of the largest planets — Jupiter, Saturn, Uranus, Neptune, and the Ninth Planet — could line up the orbits of thousands of Kuiper Belt random objects. “We are looking for everything that the ninth planet does with the solar system,” says Brown.

In an attempt to clarify the probable orbit of the planet, the researchers compared the simulation results with the actual state of the Kuiper belt. “Our work showed a synthetic Solar system that looks in many ways similar to the present,” says Batygin. “My confidence that the Ninth Planet exists, has almost taken shape already - after all, the results of calculations so well coincide with the observations.”

Further strategies include exploring the possible gravitational influence of the ninth planet on other celestial bodies. Astronomers Yuri Medvedev and Dmitry Vavilov from the Institute of Applied Astronomy of the Russian Academy of Sciences studied 768 comets that first entered the solar system, noting that five of them could come close to the ninth planet in the past, and as a result of its attraction change their course. Their analysis suggests that "the ninth planet could lure these comets into the solar system," says Vavilov. “We think comets can help narrow the field to search for the ninth planet. The discovery of additional comets would also help. ” Sheppard warns that it is necessary “to use comets with care to search for the ninth planet, since many forces can influence their orbits. But despite my skepticism, it can help. ”

The analysis of Pluto by astrophysicists Matthew Holman and Matthew Payne [Matthew Holman and Matthew Payne] of their Harvard-Smithsonian Astrophysical Center found no evidence for or against the existence of a ninth planet. In particular, this was due to the poor old archival photographs of Pluto, says Holman, which makes it difficult to know whether Pluto has shifted in orbit in a way that could confirm the presence or absence of a ninth planet. But he also argues that high-quality data on Saturn , obtained from the ground-based network of radio telescopes that monitor the Cassini spacecraft, is promising, and coincides with the calculations of Batygin and Brown.

Also, according to Holman, in analyzing the ninth planet, analysis of changes in the orbit of Mars can help. Although the planet should have less influence on Mars than on Saturn - because Mars is closer to the Sun and more closely associated with it is the gravitational - artificial satellites of Mars, and they watch the Red Planet longer, therefore "their observations are much more accurate," Holman. In addition, "Cassini produces data with an accuracy of tens of meters, and the distances between the Earth and Mars are measured with an accuracy of meters."

Stronger evidence of the influence of the ninth planet can be found in the duration of the circulation of other bodies around the sun. For example, four MICs with the longest orbits circulate according to a scheme that can be easily explained by the presence of a ninth planet - as astronomer René Malhotra, director of theoretical astrophysics at the University of Arizona at Tucson, says. Her work with two colleagues hints at the presence of two probable orbits of the ninth planet, one closer to the plane of the Solar system by 18 degrees, and the other steeper, by 48 degrees. This information can help reduce the huge search area.

Some studies limit the possible location of the ninth planet to such an extent that they can completely exclude the fact of its existence. For example, although previous studies suggest its existence due to the accumulation of orbits of some DICs, observing a limited number of DICs can only create the impression that some orbits are grouped - so, at least, astrophysicist Corey [Cory Shankman] from the University. Victoria and Samantha Lauler State Research Commission of Canada.

Brown objects that he and Batygin took into account the possibilities of such observational deviations — and that other evidence also confirms the existence of a ninth planet. For example, Brown and colleagues have found that the influence of this elusive world can uncover a long-standing riddle of why the plane of the solar system is tilted relative to the sun.

Malhotra of the University of Arizona says that he is skeptical about the possibility of the existence of the planet, but notes that they and their colleagues discovered such a tilt of the orbits of very remote defense systems, which is difficult to explain by other factors. “The degree of deformation is simply unrealistic,” she says. “As for me, this is the most intriguing proof of the existence of the ninth planet, of all that I have seen.”