Considering how long we've been thinking about a massive planet in the outer Solar System — and I'm going all the way back to Percival Lowell's Planet X here — the idea that we might find the hypothetical Planet Nine in just three years or so is a bit startling. But Caltech's Mike Brown and colleague Konstantin Batygin, who predicted the existence of the planet last January based on its effects on Kuiper Belt objects, are continuing to search the putative planet's likely orbital path, hoping for a hit within the next few years, a welcome discovery if it happens. The duo are working with graduate student Elizabeth Bailey, lead author of a new study being discussed at the American Astronomical Society's Division for Planetary Sciences meeting in Pasadena, which is occurring in conjunction with the European Planetary Science Congress. The new paper is all about angles and alignments, focusing on the fact that the relatively flat orbital plane of the planets is tilted about...

We're getting close on New Horizons data, all of which should be downlinked as of this weekend. Although that's a welcome marker, it hardly means the end of news from the doughty spacecraft. For one thing, we have years of analysis ahead of us as we bring the abundant data from the spacecraft's instrument packages into focus. For another, we're still in business out there in the Kuiper Belt, heading for that interesting object 2014 MU69. Who knows what will turn up at the latter, given our propensity to be surprised at every turn in interplanetary exploration, from Triton's volcanic plains to fabulously fractured Miranda. And, of course, Pluto and Charon themselves, which turned out to be so interesting that Alan Stern, principal investigator for New Horizons, is already talking about future missions there. But back to 2014 MU69, which has continued to be the subject of Hubble observations even as New Horizons homes in on the object. As this news release from the mission points out,...

Back in the days when I was reading Poul Anderson's The Snows of Ganymede and thought of the moons of Jupiter as icy wastelands, I never would have dreamed there could be an ocean below their surfaces. But now we have oceans proliferating. Ganymede's may contain more water than all Earth's oceans, while Callisto is also in the mix, and we've known about Europa for some time now. At Saturn, the case for an ocean inside Titan seems strong, while Enceladus continues to spark mission proposals to study its frequent geysers. If you're a Centauri Dreams regular, you know that we've talked about Pluto's oceanic possibilities for some time, now strengthened in new work from Brandon Johnson (Brown University). Johnson and colleagues have modeled an ocean layer on Pluto more than 100 kilometers thick, with a salt content more or less like that of the Dead Sea on Earth. Johnson focused on Sputnik Planum, the 900-kilometer basin that comprises part of the heart-shaped feature we all learned to...

The latest news from the Chandra X-Ray Observatory is that the spacecraft, 100 times more sensitive to X-ray sources than any previous X-ray telescope, has found that Pluto is emitting X-rays. This marks the first time we've detected X-rays from a Kuiper Belt object. In fact, until now, the previous most distant Solar System body with detected X-rays was Saturn. But four Chandra observing runs from early 2014 through the summer of 2015 have detected X-rays, in work on Pluto done in coordination with the the New Horizons effort. Carey Lisse (JHU/APL) led the Chandra observing runs, working with New Horizons co-investigator Ralph McNutt (also at JHU/APL). Says Lisse: "We've just detected, for the first time, X-rays coming from an object in our Kuiper Belt, and learned that Pluto is interacting with the solar wind in an unexpected and energetic fashion. We can expect other large Kuiper Belt objects to be doing the same." The New Horizons pass by Pluto/Charon in July of last year is a...

Deep space exploration brings a surprise with each new destination. New Horizons made the point over and over again, and today we get word of new work on one of the mission's discoveries, that dark red polar cap at the north of Pluto's large moon Charon. Will Grundy (Lowell Observatory) and colleagues are behind the study, which digs into the theory that methane from Pluto's atmosphere is trapped at Charon's north pole. In a new paper in Nature, Grundy and team have used New Horizons mission data in conjunction with their own modeling of the evolution of Charon's ice cap over the course of a Plutonian year to demonstrate that the model of trapped methane works. It involves the processing of methane into complex organic molecules called tholins. From the paper: The distribution of dark, reddish material around Charon's northern pole is notable for its generally symmetric distribution across longitudes and its gradual increase with latitude, although there are local irregularities...