In the last days of 1983 the Washington Post ran a story about an unidentified object in the direction of Orion. It described something possibly as large as Jupiter, possibly close enough to belong to our own solar system, picked up by a new satellite that could see heat rather than light.
Four decades later that story is still circulating. It is the single most cited piece of evidence that a large undiscovered planet is inbound, and it rewards careful reading, because almost everything interesting about it sits in the details that the retellings drop.
What is claimed
The claim in its strongest form runs like this. In 1983 an infrared satellite detected a massive body at the edge of the solar system. The discovery was reported in a mainstream newspaper. Then the story stopped: no follow-up, no retraction, no further comment. The silence is the tell. Something was found, and the finding was withdrawn from public view.
Around that core sits a larger structure. The object is identified with Nibiru, a planet held to travel a long elliptical orbit and to return periodically, causing catastrophe when it does. Arrival dates have been issued repeatedly. One widely promoted date fell in 2003. Another was folded into the 2012 material drawn from the Maya long count. Further dates have followed each time an earlier one passed without incident.
Where it came from
The satellite was real and the story was real, which is why this particular claim has outlived so many others.
IRAS, the Infrared Astronomical Satellite, was a joint project of the United States, the Netherlands and the United Kingdom, launched in 1983. It carried a telescope cooled with liquid helium and it completed the first survey of the entire sky in infrared light. That was a genuine landmark. Infrared registers heat rather than reflected sunlight, which makes it exactly the right instrument for finding cold, dark objects that visible-light telescopes cannot see.
A survey on that scale produces enormous numbers of detections, and a fraction of them are always unidentified on the first pass. In late December 1983 a Washington Post reporter interviewed astronomers working with the data about several such sources. The resulting article was speculative and said so. The scientists quoted offered a range of possibilities: a distant galaxy, a protostar, or, at the far end of the range, a body within our own solar system.
That range is what the retellings lose. The article did not announce a discovery. It reported that something had been detected, that it had not yet been identified, and it listed the candidates. The most dramatic candidate travelled. The list did not.
What the record shows
The unidentified sources were identified. Follow-up work resolved them into two unremarkable categories: distant galaxies that are bright in infrared, and infrared cirrus, the wispy interstellar dust inside our own galaxy that IRAS was sensitive enough to detect for the first time. Cirrus was itself a real discovery and a considerable nuisance, because it produced precisely the sort of faint, extended, hard-to-classify sources that turn up on a list of unknowns.
The astronomers involved stated publicly, more than once, that no planet had been found. That is the follow-up whose absence the claim depends on.
A second thread deserves separating out, because it is routinely merged with the first. Through the 1980s there was a genuine, respectable scientific search for a Planet X. It had nothing to do with IRAS. It arose from small discrepancies between where Uranus and Neptune were predicted to be and where they were actually observed, and an unseen massive planet was one reasonable explanation for the gap.
That search closed for an unglamorous reason. When Voyager 2 passed Neptune in 1989 it allowed a far better measurement of the mass of Neptune. Recalculating the orbits with the corrected value made the discrepancies dissolve. There was no residual left to explain. The Planet X of the 1980s turned out to be an error bar.
The sky has been searched again since, with better instruments. The WISE infrared survey, which mapped the whole sky around 2010, was used to exclude a Saturn-sized object out to roughly ten thousand astronomical units, and a Jupiter-sized one considerably further. A large planet on a short return orbit is not merely undetected. It is the specific thing those surveys were built to find, and they did not find it.
Planet Nine is a different argument
None of this makes the outer solar system empty. In 2016 two astronomers at Caltech proposed a distant planet of perhaps five to ten Earth masses, several hundred astronomical units out, on the grounds that the orbits of a number of extreme trans-Neptunian objects appear clustered in a way that coincidence does not comfortably explain. That hypothesis is live, contested, and pursued through ordinary astronomy.
It is worth being precise about how little it resembles the Nibiru claim. Planet Nine is proposed to be far away and to stay far away, on an orbit measured in thousands of years. It is not inbound. It carries no arrival date. It was not concealed; it was published, argued over, and searched for in the open. The two ideas share a rough silhouette and nothing else.
Why the story survives
The 1983 article endures because it has the shape of a good story and almost none of the friction of a bad one. A real satellite, a real newspaper, real scientists, and a real remark about something possibly the size of Jupiter. Every element checks out on its own.
What does not survive is the sentence assembled out of them. The detections were made, and they were also identified, and the identification sits on the record under the names of the people who did the work. The silence the claim rests on is not silence. It is a body of follow-up literature that is simply less quotable than the headline that came first.