ANN ARBOR – Seeing is believing, but with regard to the New Planet, complex calculations of the behavior of space objects, careful observation of orbital anomalies and careful observation of the region beyond Neptune will have to be made for the time being.
"The strongest argument in favor of Planet Nine is that independent data sources can all be explained by a proposed new planet having the same properties. In other words, there are many reasons to believe that Planet Nine is real, not one, "said Fred Adams, professor of physics (and astronomy) at Ta-You Wu College in University of Michigan.
Three years ago, astronomers Konstantin Batygin and Mike Brown of Caltech hypothesized the existence of a ninth planet in the solar system, beyond Neptune, which would explain why certain objects in space, called "trans-Neptunian objects", behave as they do.
Since then, astronomers have been busy collecting evidence of its existence. Batygin, Brown and Adams, as well as Ph.D. candidate Juliette Becker of U-M's Department of Astronomy, recently examined this data in the article "The Planet Nine Hypothesis", published this month by Physics Reports.
"While this analysis does not say anything directly about Planet Nine's presence, it nonetheless indicates that the hypothesis rests on a solid foundation," said co-author Mike Brown, professor of planetary astronomy Richard and Barbara Rosenberg in Caltech.
Adams said he is optimistic that in the next 10 to 15 years, we will either be able to observe Planet Nine or have enough data to exclude it. Over the last two decades, the number of discoveries of new solar system objects and extrasolar planets has increased exponentially. For example, the four authors of the report have collectively discovered dozens of such objects and the rate of detections is well placed to increase.
"With its proposed properties, Planet Nine is about to be observable," said Adams, adding that if we knew where he was in the sky, we could steer a telescope in the right direction and see it. "But it's a very dark object in a very big sky. Since we do not know exactly where it is, you must explore all the sky, or at least a large part of it, to find the planet.
"Over the next 10 years, we will have deeper and deeper soundings, which means more sensitive. So I think that by 2030, we will have seen or have a better idea of where it is located. Of course, it is also possible that we may have other explanations for observed orbital anomalies. "
For Becker, finding Planet Nine would help many of the mysteries of the solar system, including the origin of a rock object called 2015 BP519.
"Planet Nine is a very good explanation for 2015 BP519: Physics works perfectly. However, as long as we do not see Planet Nine in an image and we are certain of it, I do not think we have really solved the mystery of its origin, "she said.
"The presence of Planet Nine would respond beautifully and coherently to several open questions apparently unrelated to the solar system. I look forward to the day we will see it or eliminate it in order to be able to answer these questions conclusively. "
On the basis of new models and detailed calculations presented in the journal, the researchers estimate that Planet Nine has a mass about five times higher than Earth's and has an orbital semi-major axis located near 400 astronomical units, which makes it smaller and closer to the Sun. than previously suspected – and potentially brighter. Each astronomical unit is equivalent to the distance between the center of the Earth and the center of the Sun, about 149.6 million kilometers.