The list of planets in our solar system may be returning to nine, with the announcement that scientists may have found a giant planet, 5,000 timer larger than Pluto, which had been earlier removed from the list of planets, according to Fox News.

The mysterious planet, which the scientists are calling Planet Nine, has an orbit around the Sun that would take an estimated 10,000 to 20,000 Earth years to complete, and its orbit is about 20 times farther from the Sun than the orbit of Neptune.

The discovery was made by CalTech researcher Mike Brown, who was a part of the demotion of Pluto from the planet list, and his colleague Konstantin Batygin.  Brown said the planet gravitationally dominates its surrounding neighbors, more so than any other planet, and added it was “the most planet-y of the planets in the whole solar system.”

Batygin, an assistant professor of planetary science, said they were initially skeptical about the existence of this planet, but their continued investigation of its orbit made them increasingly confident that it was there.  Batygin continued by saying it was the first time in over 150 years that there was solid evidence that the current list of planets in the solar system was not complete.

Brown says the new information  suggests there may have been five planetary cores that marked the beginning of the universe, instead of four.  It has been believed that the original four cores collected all the gases near them, and led to the formation of Jupiter, Saturn, Uranus and Neptune.  Brown speculates the Planet Nine could have been the fifth planetary core, and possibly was kicked out into the deep reaches of the solar system as it got too close to either Jupiter or Saturn.

Brown adds, “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.”

A description of the work by the team appears in the current issue of the Astronomical Journal.