The astronomer known worldwide for vigorously promoting the demotion of Pluto from its decades long perch as the 9th Planet, has now found theoretical evidence for a new and very distant gas giant planet lurking way beyond Pluto out to the far reaches of our solar system.

In an obvious reference to the planethood controversy, the proposed new planet is nicknamed ‘Planet Nine’ and its absolutely huge!

The possible planet has a mass about 10 times that of Earth and is believed to be gaseous, like Uranus and Neptune, according to Mike Brown of Caltech, who became famous during the contentious debate on Pluto’s planetary status. He announced the new finding today, Jan. 20, along with fellow Caltech researcher Konstantin Batygin.

The giant new planet orbits the sun some 20 times farther out than Neptune in the distant reaches of the Kuiper Belt. Neptune orbits the sun at an average distance of 2.8 billion miles (4.5 Billion km).

Astronomers have been searching for decades for “Planet X” a large theorized planet beyond the orbit of Pluto. Pluto’s eccentric orbit ranges from 4.4–7.4 billion km.

The theorized ‘Planet Nine’ travels in a highly elongated path that takes between 10,000 and 20,000 years to complete just one full orbit around the sun, according to Caltech statement describing the work.

Caltech astronomers Mike Brown and Konstantin Batygin coauthored a paper describing their work on the discovery of the existence of the proposed gas giant in the current issue of the Astronomical Journal.

The paper is titled; “EVIDENCE FOR A DISTANT GIANT PLANET IN THE SOLAR SYSTEM” and is available here.

“This would be a real ninth planet,” says Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy, in a statement.

“There have only been two true planets discovered since ancient times, and this would be a third. It’s a pretty substantial chunk of our solar system that’s still out there to be found, which is pretty exciting.”

So far there is no confirmation of the existence of the planet.

It has not actually been observed but its existence is theorized through complex mathematical modeling and computer simulations.

Brown’s discovery of Eris in 2005, which orbits farther out than Pluto and is almost the same size as Pluto but smaller, sparked the IAU to demote Pluto to a dwarf planet in 2006.

In 2010 Brown wrote a book about the planet debate titled; “How I Killed Pluto and Why It Had It Coming.”

Many planetary scientists, led by Alan Stern, do not agree with or accept the reclassification and demotion.

Stern is the Principal Investigator of NASA’s New Horizons probe which carried out history’s first flyby of Pluto on July 14, 2015.

Among its numerous discoveries, New Horizons found that Pluto is a very geologically world even today and larger than Eris, and thus reigns as undisputed “King of the Kuiper Belt!”

In the Astronomical Journal paper, Batygin and Brown “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.

“For the first time in over 150 years, there is solid evidence that the solar system’s planetary census is incomplete.”

In a prior interview, Alan Stern has told me that he believes that a planet at least as large as Mars lurks somewhere far out in the Kuiper Belt.

Meanwhile Batygin and Brown are hunting for ‘Planet Nine’ and they encourage others to search too.

Since they only know the rough orbit of the object, they continue to “refine their simulation” to better pin down its location to more productively aim the telescopes along the highly elliptical path.

“I would love to find it,” says Brown. “But I’d also be perfectly happy if someone else found it. That is why we’re publishing this paper. We hope that other people are going to get inspired and start searching.”

Here’s a comment from NASA’s Director of Planetary Sciences Jim Green, about today’s discovery:

Video caption: A New Planet In Our Solar System? NASA Takes A Look . NASA’s Director of Planetary Science, Jim Green, discusses the Jan. 20 Astronomical Journal science paper that points to the possibility of a new “Planet 9” in our solar system beyond Pluto, examining the scientific process and inviting you to have a front row seat to our exploration of the solar system.

“The idea of a new planet is certainly exciting for all of us,” says Green. “The paper is stimulating a healthy debate that’s part of the scientific process. This isn’t the detection of a planet. It’s too early to say with certainty that there is a so-called Planet X out there. This is an early prediction based on limited observations. It stimulates ideas.”

“Now let’s go explore!”

Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer