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Planet Nine will probably be detected within a decade, if the putative world does exist, suggests a new study.
Three years ago, Caltech astronomers Konstantin Batygin and Mike Brown estimated that the so-called Planet Nine – also known as Planet X, Giant Planet Five, or Planet Next – may be 10 times more massive than Earth and lopes around the sun at an average distance of 600 astronomical units (AU). (An AU is the Earth-Sun distance – about 93 million kilometers, or 150 million kilometers.)
However, in a long and detailed new article, Batygin, Brown and two other researchers have determined that the putative planet is probably smaller and less extensive than this one.
Related: Evidence of the "New Planet" in our solar system (Gallery)
The orbits of objects distant from the Kuiper belt and the Planet Nine hypothesis. The orbits made in purple are mainly controlled by the gravity of Planet Nine and have a narrow orbital grouping. Green orbits are strongly coupled to Neptune and have a wider orbital dispersion. The updated orbital calculations suggest that Planet Nine is a planet with a mass of about 5 Earth mass that resides in a slightly eccentric orbit with a period of about 10,000 years.
(Image: James Tuttle Keane / Caltech)
According to the new study, observations and computer modeling indicate that 10 land masses are Planet Nine's upper limit. Indeed, scientists have found that 5 land masses and an average orbital distance of 400 to 500 AU would be closer to the actual markings.
And that means Planet Nine is probably easier to spot than scientists suspected.
"Perhaps counter-intuitively, the increase in brightness due to a smaller heliocentric distance more than compensates for the decrease in luminosity due to a slightly reduced physical radius, suggesting that Planet Nine is more easily detectable by optical soundings. conventional than previously thought, "says Batygin. his colleagues wrote in the newspaper. The study was published online this month in the journal Physics reports. You can read it for free at the online pre-print site. arXiv.org.
Indeed, the pan-lift telescope and rapid response system (Pan-STARRS) project in Hawaii could well spy on Planet Nine from one day to the next. And even if the hypothetical world is darker and more distant, it will probably still be detectable by the Great Synoptic Telescope, which is expected to go online in Chile in the early 2020s, the researchers said.
"Therefore, Planet Nine – if it exists as described here – will probably be discovered a decade ago," they wrote in the study.
The recently published document also summarizes the case of the existence of Planet Nine, organizing the observations available in four data sources. All four deal with the peculiarities of orbits of small objects emerging from icy chasms beyond the orbit of Neptune.
These peculiarities are best explained by the existence of a far distant "great", whose gravity has guided the objects on their current trajectories, wrote the researchers. (The magnitude of this sculpting effect is determined by both the mass of the disrupter and the distance to the sun.A smaller than expected Planet Nine should therefore be closer to the sun to produce the observed results. )
"Although this analysis does not say anything directly about Planet Nine's presence, it nonetheless indicates that the hypothesis rests on a solid foundation," Brown said. said in a statement.
This foundation is indeed very strong, said Batygin. In a conversation with Space.com last fall, he estimated that the probability of the world's existence was "over 90%". Another key player in the hunt for planet Nine, Scott Sheppard of the Carnegie Institution for Science, is also bullish, placing the probabilities between 80 and 90%.
It may seem strange that an object considerably larger than the Earth can remain so long hidden in our own solar system. But the neighborhood of Planet Nine is extremely remote; for perspective, Pluto rotates around the sun at an average distance of only 39.5 AU. Thus, Planet Nine is likely to be quite weak and its orbital path is huge, which means that astronomers have a lot of ground to explore.
"We have covered very little sky to the depth that we have to cover to find something so weak," Sheppard said Space.com last fall. "You can very easily hide a very big thing in the external solar system."
Mike Wall's book on the search for extraterrestrial life, "Over there"(Grand Central Publishing, 2018, illustrated by Karl Tate), is out now. Follow him on Twitter @michaeldwall. Follow us on twitter @Spacedotcom or Facebook.
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