A duo of planetary astronomers has grabbed media attention by claiming a planet four times the size of Jupiter may be lurking in the outer solar system. They call the planet Tyche.
Many astronomers, however, say it probably isn't there.
The claim by John Matese and Daniel Whitmire of the University of Lousiana-Lafayette is not new: They have been making a case for Tyche since 1999, suggesting that the giant planet's presence in a far-flung region of solar system called the Oort cloud would explain the unusual orbital paths of some comets that originate there.
"There's evidence that some Oort cloud comets display orbital peculiarities," Matese said. "We're saying that perhaps the pattern is indicative that there's a planet there."
Although their argument is similar to the one they originally made, "what's new is that this pattern has persisted," Matese told Life's Little Mysteries. "It's possible that it's a statistical fluke, but that likelihood has lessened as more data has accumulated in the past 10 years."
Matese says NASA's WISE telescope may have already collected infrared data from Tyche that would be hard to pick out from within the telescope's immense database.
"The spectrum we have predicted is uncertain, and there may be a great many signals that are similar to what are expected for our object. So this may take time," Matese said. It could be two years before a signal from Tyche — if it's there — is located, he added.
Not everyone is as optimistic.
Required: 'Incredible proof'
Matthew Holman, a planetary scientist at the Harvard Smithsonian Institute of Astrophysics, is not a Tyche believer.
Though he hasn't read the latest version of Matese's and Whitmire's argument, Holman told Life's Little Mysteries, "Based on past papers that I've seen looking at where long-period comets came from in the sky, and finding signatures of large perturbers of the Oort cloud, I was not persuaded by the evidence."
Hal Levison, a planetary scientist at the Southwest Research Institute in Boulder, Colo., who recently authored a paper on the Oort cloud for Science Magazine, seconded that opinion.
"I haven't read this version of his paper, which he claims now has better statistics than the previous attempts, where he also claimed that he saw evidence of this object," Levison said. "But in previous papers, I really think he did his statistics wrong. Incredible claims require incredible proof and I really believe that he doesn't understand how to do this statistical analysis correctly."
"What Matese claims is that he sees an excess of comets coming from a particular place, which he attributes to the gravitational effects of a large planet in the Oort cloud. I have nothing against the idea, but I think the signal that he claims he sees is very subtle, and I'm not sure it's statistically significant," Levison told Life's Little Mysteries.
"There's another group in England that claims the same thing, but with Jupiter on the other side of the sun," Levison said. "And they also claim to explain the excess of comets."
As always, it's difficult to prove or disprove anything that you can't see or touch, but for now, considering that most astronomers aren't even sure that such an excess of comets exists in the first place, it may be too early to get psyched about Tyche.
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Natalie Wolchover was a staff writer for Live Science and a contributor to Space.com from 2010 to 2012. She is now a senior writer and editor at Quanta Magazine, where she specializes in the physical sciences. Her writing has appeared in publications including Popular Science and Nature and has been included in The Best American Science and Nature Writing. She holds a bachelor's degree in physics from Tufts University and has studied physics at the University of California, Berkeley.