Mystery of the ninth planet

Mystery of the ninth planet

Will scientists be able to find another large object in the solar system? We talk about the search for another planet in the solar system in conjunction with the popular science portal N + 1.

In the astronomical environment for two years, discuss a sensation, which is not yet. In the winter of 2016, scientists at the California Institute of Technology Konstantin Batygin and Michael Brown published an article that once again revived hopes that another planet could be found in the solar system. A number of indirect signs indicate that somewhere far beyond Pluto, there is another planet. While it was not found, but the approximate location calculated. If there is no error in the calculations, this will be the most important astronomical discovery of the century.

The first planet, open “at the tip of the pen,” was Neptune – back in the 1830s, astronomers noticed unforeseen deviations in the orbit of Uranus and suggested that behind it there is another planet that causes gravitational perturbation. The hypothesis was confirmed in 1846, when Neptune was able to observe in the mathematically predicted region of the sky. It turned out that he had been seen before, but could not be distinguished from distant stars. The average distance to Neptune is 4.5 billion kilometers, or about 30 astronomical units (one astronomical unit is equal to the distance from the Sun to the Earth — about 150 million kilometers).

snapshot of Neptune

Optimism after the discovery of Neptune inspired many scientists and amateur astronomers to search for other, more distant planets. Further observations of Neptune and Uranus showed the discrepancy between the real motion of the planets and the predicted mathematically, and this instilled confidence that the sensation of 1846 could be repeated. It seemed that in 1930 the search was crowned with success when Clyde Tombo discovered Pluto at a distance of about 40 astronomical units.

For a long time, Pluto remained the only known object in the Solar System, located farther from the Sun than Neptune. And as the quality of astronomy technology grew, ideas about the size of Pluto were constantly changing towards decreasing. By the middle of the century, it was believed that it had a size comparable to the Earth, and a very dark surface. In 1978, it was possible to clarify the mass of Pluto due to the discovery of its satellite Charon. It turned out that it is much less than that of Mercury, but even of the Earth’s Moon.

By the end of the 20th century, discoveries of other trans-Neptunian objects, smaller than Pluto, began thanks to digital photography and computer data processing technologies. At first, out of habit, they were called planets. In the solar system there were ten, then eleven, then twelve. But by the early 2000s, astronomers had sounded the alarm. It became clear that behind Neptune the Solar system does not end and each ice block does not give the status of the Earth and Jupiter. In 2006, a separate name was invented for pluton-like bodies – a dwarf planet. The planets were eight again, like a century ago.

Meanwhile, the search for real planets outside the orbits of Neptune and Pluto did not stop. There were even hypotheses about the presence of a red or brown dwarf there, that is, a small star-like body weighing several dozens of Jupiters, which makes up the double star system with the Sun. This hypothesis was suggested by … dinosaurs and other extinct animals. A group of scientists drew attention to the fact that mass extinctions on Earth occur approximately every 26 million years, and suggested that this is a return period in the vicinity of the inner solar system of a massive body, which leads to an increase in the number of comets heading towards the Sun and entering the Earth. In many media, these hypotheses came in the form of unscientific predictions about the impending attack of aliens from a planet or star Nibiru.

graph of extinction of species on Earth

NASA has twice attempted to find a possible planet or brown dwarf. In 1983, the IRAS space telescope made a complete mapping of the celestial sphere in the infrared. The telescope made observations of tens of thousands of sources of thermal radiation, discovered several asteroids and comets in the solar system, and caused the hype in the press when scientists mistakenly recognized a distant galaxy as a jupiter-like planet. In 2009, a similar, but more sensitive and long-lived WISE telescope flew, which managed to find several brown dwarfs, but a few light-years away, that is, not related to the Solar System. He also showed that in our system of planets the size of Saturn or Jupiter beyond Neptune either.

To see a new planet or a nearby star, no one has managed so far. Or it is not there at all, or it is too cold and emits or reflects too little light to be detected during a random search. Scientists have to rely on indirect signs: the features of the motion of other, already open, cosmic bodies.

Initially, encouraging data was obtained in the anomalies of the orbits of Uranus and Neptune, but in 1989 it was established that the cause of the anomalies was in the erroneous determination of the mass of Neptune: it was five percent lighter than previously thought. After correcting the data, the modeling began to coincide with the observations, and the hypothesis about the ninth planet disappeared.

Some researchers thought about the reasons for the appearance of long-period comets in the inner solar system and about the source of short-period comets. Long-period comets can appear in the Sun once in hundreds or millions of years. Short-period fly around the sun for 200 years or less, that is, they are much closer.

Comets have a very short life time for cosmic standards. Their main material is ice of various origins: from water, methane, cyan, etc. The sun’s rays evaporate ice, and the comet turns into an imperceptible stream of dust.

flyby comet near the sun

Nevertheless, short-period comets continue to fly around the Sun today, billions of years after the formation of the Solar System. This means that their number is replenished from some external source.

Such a source is considered the Oort Cloud – a hypothetical region with a radius of up to 1 light year, or 60 thousand astronomical units, around the Sun. It is believed that there are flying millions of ice pieces in circular orbits. But from time to time something changes their orbit and launches towards the Sun. What is this force is still unknown: it may be a gravitational perturbation from neighboring stars, the results of collisions in a cloud or the influence of a large body in it. For example, it could be a planet just a little larger than Jupiter – it was even given the name Tyuhe. The authors of the Tyukhe hypothesis assumed that the WISE telescope could find it, but the discovery did not take place.

If the Oort Cloud is only a hypothetical family of small bodies in the solar system, which astronomers cannot observe directly, then the other family, the Kuiper belt, is much better studied. Pluto is the first detected Kuiper belt cosmic body. Now there are open three more dwarf planets the size of Pluto or less and more than a thousand small bodies.

Kuiper Belt

The Kuiper Belt family is characterized by circular orbits, a small inclination to the plane of rotation of the known planets of the Solar System – the ecliptic plane – and a revolution within 30 and 55 astronomical units. From the inside, the Kuiper belt breaks off in the orbit of Neptune, and besides this planet exerts a gravitational perturbation on the belt. The cause of the outer sharp border of the belt is unknown. This suggests that there is another full-fledged planet somewhere at a distance of 50 astronomical units.

Behind the Kuiper belt, though partially intersecting with it, lies the region of the scattered disk. For the small bodies of this disk, on the contrary, highly elongated elliptical orbits and a significant inclination to the ecliptic plane are characteristic. New hopes for the discovery of the ninth planet and stormy discussions among astronomers have generated precisely the bodies of the scattered disk.

Some objects of the scattered disk are so far from Neptune that it does not exert any gravitational influence on them. For them, a separate term “isolated trans-neptune object” was coined. One of such famous objects called Sedna approaches the Sun by 76 astronomical units and moves away by 1000 astronomical units, so it is simultaneously considered the first object of the Oort Cloud. Some known bodies of a scattered disk have less extreme orbits, and some, on the contrary, have an even more elongated orbit and a strong inclination of the plane of revolution.

orbits of trans-Neptunian objects

It turned out that several of the isolated trans-Neptunian objects found have a near point of their orbit in the region of about 60 astronomical units and this point lies in the plane of the ecliptic, and for some objects the orbits are elongated in one direction. The probability of such an accidental orbit running is 0.025 percent, that is, the gravitational influence of an unknown planet is more likely. Scientists from the California Institute of Technology Konstantin Batygin and Michael Brown, who have paid attention to unusual orbits, estimate that this planet may be ten times more massive than the Earth. Perhaps there is a gas fellow Neptune and Uranus flying there, or a stone planet 2-4 times larger than the Earth, the so-called “super-earth”. Although, given the abundance of ice bodies on the periphery of the solar system, the presence of a gas planet is more likely.

According to the calculations of the authors of the fresh hypothesis, “their” planet can have an elongated orbit, approaching the Sun by 200 and moving away by 1200 astronomical units. Its exact location on the earth’s sky has not yet been calculated, but the approximate area of ​​searches is gradually shrinking.

search ninth planet

The search is conducted using the Subaru optical telescope in Hawaii and the Victor Blanco telescope in Chile. In order to further confirm the existence of the planet and to clarify its possible location, it is required to find more bodies of the scattered disk. Now these searches continue, work has a high priority, and new finds appear. However, the expected planet is still elusive.

If astronomers knew where to look, then perhaps they could see the planet and estimate its size. But the “long-range” telescopes are too narrow viewing angle to carry out a free search in large areas of the sky. For example, the well-known Hubble space telescope for 25 years of its work examined less than 10 percent of the entire celestial sphere. But the search continues, and if the ninth planet of the solar system is found, it will be a real sensation in astronomy.

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