Planet nine found in our solar systemAmy Walsh (Author) Published Date : Jan 21, 2016 21:47 ET
How many planets are there in the solar system Well, an answer that most of us know and to add to that, evidence of planet nine has been discovered by Caltech researchers. The object, which the researchers have nicknamed Planet Nine, has a mass about 10 times that of Earth and orbits about 20 times farther from the sun on average than does Neptune. In fact, it would take this new planet between 10,000 and 20,000 years to make just one full orbit around the sun.
The researchers, Konstantin Batygin and Mike Brown, discovered the planet's existence through mathematical modeling and computer simulations but have not yet observed the object directly.
This would be a real ninth planet, says Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy.
Brown notes that the putative ninth planet, at 5,000 times the mass of Pluto, is sufficiently large that there should be no debate about whether it is a true planet.
Batygin and Brown describe their work in the current issue of the Astronomical Journal and show how Planet Nine helps explain a number of mysterious features of the field of icy objects and debris beyond Neptune known as the Kuiper Belt.
Although we were initially quite skeptical that this planet could exist, as we continued to investigate its orbit and what it would mean for the outer solar system, we become increasingly convinced that it is out there, says Batygin, an assistant professor of planetary science.
The road to the theoretical discovery was not straightforward. In 2014, a former postdoc of Brown's, Chad Trujillo, and his colleague Scott Shepherd published a paper noting that 13 of the most distant objects in the Kuiper Belt are similar with respect to an obscure orbital feature. To explain that similarity, they suggested the possible presence of a small planet. Brown thought the planet solution was unlikely, but his interest was piqued.
He took the problem down the hall to Batygin, and the two started what became a year-and-a-half-long collaboration to investigate the distant objects.
Fairly quickly Batygin and Brown realized that the six most distant objects from Trujillo and Shepherd's original collection all follow elliptical orbits that point in the same direction in physical space.
By accident, Batygin and Brown noticed that if they ran their simulations with a massive planet in an anti-aligned orbit, an orbit in which the planet's closest approach to the sun, or perihelion, is 180 degrees across from the perihelion of all the other objects and known planets, the distant Kuiper Belt objects in the simulation assumed the alignment that is actually observed.
And indeed Planet Nine's existence helps explain more than just the alignment of the distant Kuiper Belt objects. It also provides an explanation for the mysterious orbits that two of them trace.
Where did Planet Nine come from and how did it end up in the outer solar system
Batygin and Brown continue to refine their simulations and learn more about the planet's orbit and its influence on the distant solar system. Meanwhile, Brown and other colleagues have begun searching the skies for Planet Nine. Only the planet's rough orbit is known, not the precise location of the planet on that elliptical path.
Brown, well known for the significant role he played in the demotion of Pluto from a planet to a dwarf planet adds, All those people who are mad that Pluto is no longer a planet can be thrilled to know that there is a real planet out there still to be found, he says.
The paper is titled Evidence for a Distant Giant Planet in the Solar System.
Planet nine found in our solar system