Outer Solar System

Pluto: Sputnik Planitia Gives Credence to Possible Ocean

November 16, 2016

We’ve been looking at the idea of an ocean beneath Pluto’s icy surface for some time, including interesting work on the thermal evolution of the dwarf planet’s ice shell from Guillaume Robuchon and Francis Nimmo (University of California at Santa Cruz). Back in 2011, The Case for Pluto’s Ocean looked at their view that the […]

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Ring Formation: Clues from the Late Heavy Bombardment

November 2, 2016

Let’s circle back this morning to ring systems, which were the subject of Monday’s post. In particular, I was interested in new work on the rings of Uranus, for Voyager data, newly analyzed, has revealed patterns that indicate the presence of small ‘shepherding’ moons. We’ve seen the same phenomenon at Saturn, but what similarities exist […]

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Uranus: New Work from Voyager Data

October 31, 2016

The ring system of Uranus was the second to be discovered in our Solar System. You would assume this came about because of Voyager, but the discovery was actually made in 1977 through ground-based observations involving occultations of distant stars. The rings of Uranus are narrow — between 1 and 100 kilometers in width — […]

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Titan’s Seasons Studied as Cassini Team Plans ‘Grand Finale’

October 21, 2016

Witnessing Titan’s ever-changing seasons has been a major payoff of the Cassini mission, whose end is now close enough (September, 2017) to cause us to reflect on its accomplishments. We now see winter settling in firmly in the southern hemisphere, along with a strong vortex now developing over the south pole. When Cassini arrived in […]

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New Work on Planet Nine

October 20, 2016

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 […]

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New Horizons: Looking Further Out

October 19, 2016

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 […]

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On Outer System Oceans

October 5, 2016

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 […]

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Puzzling Out Pluto’s X-Ray Emissions

September 19, 2016

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 […]

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On Charon’s Unusual North Pole

September 14, 2016

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 […]

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Last Images of Titan’s Far South

September 8, 2016

Have a look at an image Cassini acquired on July 25 of this year during its T-121 flyby of Titan. Here we’re dealing with a synthetic-aperture radar image, but one that has been cleaned up with a ‘denoising’ algorithm that produces clearer views. Because of its proximity to the Xanadu region, the mountainous terrain shown […]

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