When astronomers at the California Institute of Technology in Pasadena announced in January that they’d discovered a giant planet in our outer solar system, they ignited a frenzied debate over whether it was really out there, far beyond Neptune.

But the conversation hasn’t been limited to scientists. A separate discussion has been taking place among a passionate group of stargazers who have been looking for what they believe is the lost planet of Nibiru. For them, the discovery has raised the prospect that Nibiru — long dismissed as science fiction — has been found.

“It was very exciting to see scientists finding another planet in our solar system or evidence of it,” said Janet Sitchin, whose uncle, Zecharia Sitchin, proposed the existence of Nibiru.

“It’s exciting because some of the naysayers were saying how could there be such a large body in our solar system and we don’t know about it,” she told FoxNews.com. “These are people who are not astronomers and don’t know how vast space is.”

Zecharia Sitchin, who died in 2010 at the age of 90, proposed in his 1976 book, “The 12th Planet,” that Sumerian and Babylonian mythology offered proof that such a planet existed, and that its inhabitants, the Anunnaki, visited Earth around 600BC.

Sitchin claimed the planet, which he named Nibiru, was located far beyond Neptune, but that its orbit brought it close to Earth every 3,600 years, enabling the Anunnaki to interact with humans.

The Anunnaki mined for gold in the Persian Gulf and the southern part of Africa, Janet Sitchin said on a Slooh Community Observatory broadcast dedicated to Nibiru. “They found it was hard work, and they genetically engineered man. This is what ancient Sumerians wrote.”

Her uncle wrote more than a dozen books spreading the gospel of Nibiru, and they spawned countless conspiracy theories — including that Nibiru will eventually crash into Earth and that NASA has been hiding the truth about it.

SPACE: Caltech Researchers Say Ninth Planet Exists Past Pluto January 20 Researchers from the California Institute of Technology (Caltech) say they have found evidence that there is a ninth planet in the solar system outside of the orbit of Pluto. Astronomers Konstantin Batygin and Mike Brown published research on gravitationally anomalies in an area of the outer solar system known as the Kuiper Belt which could point to the existence of a planetary body 5,000 times the mass of Pluto. No direct observations have yet been made to confirm the existence of the ninth planet. This video from Caltech features an interview with the researchers and an animation explaining their theory. Credit: YouTube/Caltech

Nancy Lieder, a Wisconsin native with her own website, is one of the collision theory’s most vocal advocates. In 1995, she warned the planets would collide in 2003, and that the collision would flip the Earth’s magnetic poles. When the world failed to end that year, she pushed the date forward, saying it would coincide with the Mayan Calendar conspiracy of 2012 — resulting in upwards of 2 million websites discussing the collision, according to NASA.

Now, to the annoyance of NASA and prominent astronomers, the prospect of a Planet X deep in the solar system is reviving interest in Nibiru.

“We have a pretty good grasp of what is in our solar system out to a certain distance based on our telescopes. There is nothing out there like Nibiru,” Jim Green, director of planetary science at NASA, told FoxNews.com.

“From any scientific perspective, we have moved on. For those that haven’t, we are happy to help them move on and give them the straight scoop. That is what we do.”

Green dismissed suggestions that NASA was holding back on the “truth” about Nibiru to avoid setting off a global panic. “There must be something about humans not believing in the science,” he said.

“All I can say is we have people who don’t believe we landed on the moon. With the lunar reconnaissance orbiter, we even have high resolution imaging showing what we left on the moon, where it was and where we went to many of the Apollo sites, which clearly demonstrates we were on the moon. So, we are open and honest of what we do. That is a hallmark of NASA.”

Evidence of a Ninth Planet Caltech's Konstantin Batygin, an assistant professor of planetary science, and Mike Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy, discuss new research that provides evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system. Courtesy: YouTube/caltech.

Mike Brown and Konstantin Batygin, the scientists who spotted what may be our ninth planet, did not return calls, but Harold Levinson, who studies astronomical objects at the Southwest Research Institute, said there is no way the discovery could be Nibiru, even if it were real.

“It is scientifically impossible the Sumerians knew anything about this object, or that anything could have lived there,” Levinson wrote in an email.

“It is likely a gas giant and very, very cold. Also, the orbit of this object must be very stable in order to have the dynamical effect that Mike and Konstantin found. As such, it is never going to get anywhere near the Earth. If this object is real, it has nothing to do with these crazy ideas.”

The new planet, believed to have a mass about 10 times that of Earth, is about 20 times farther from the sun than Neptune and takes between 10,000 and 20,000 years to make just one full orbit.

“The length of orbit is very different. So. unless there is something that is not quite correct in the calculations of 10,000 and 20,000 years, then it doesn’t correspond to what the Sumerians wrote about Nibiru,” said Janet Sitchin, who works to keep her uncle’s legacy alive through the website.

But she remains convinced that Nibiru is out there, even if the newly discovered planet isn’t it.

“However,” she told Slooh, “it could be that those calculations aren’t 100 per cent right. I hope we find that it’s closer and is Nibiru, or maybe there is another planet that is Nibiru and this is not it.

“I’m also hoping that, in the search for this planet, we might find Nibiru.”