Outer Solar System

A Fresh Look at Rhea

March 31, 2015

When it comes to Saturn, have you noticed what’s been missing lately? Well, actually for the last two years. While the Cassini orbiter has had high-profile encounters with Titan, it has been in a high-inclination orbit that has meant no recent flybys of other Saturnian moons. All that has now changed as Cassini returned to […]

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Chariklo & Chiron: Centaurs with Possible Rings

March 19, 2015

You may be forgiven if you aren’t familiar with the name Chariklo. Discovered in 1997, 10199 Chariklo is a ‘centaur,’ an outer system body with an orbit that moves between the orbits of Saturn and Uranus, just nudging the orbit of the latter. Its odd name (we’re big on names and their derivations here) comes […]

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Evidence Mounts for Ganymede’s Ocean

March 13, 2015

Yesterday’s discussion of hydrothermal activity inside Saturn’s moon Enceladus reminds us how much we can learn about what is inside an object by studying what is outside it. In Enceladus’ case, Cassini’s detection of tiny rock particles rich in silicon as the spacecraft arrived in the Saturnian system led to an investigation of how these […]

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Hydrothermal Activity in the ‘Broken Heart’ of Enceladus

March 12, 2015

Enceladus has been a magnet for investigation since 2005, when the Cassini spacecraft began to reveal the unusual activity at the moon’s south pole, where we subsequently learned that geysers of water ice and vapor laden with salts and organic materials were spraying into space from deeply fractured terrain. Subsequent studies have homed in on […]

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Searching for Exoplanet Rings

March 9, 2015

Not long ago we looked at the discovery of what appears to be a disk orbiting the huge gas giant J1407b (see Enormous Ring System Hints of Exomoons). The example of Saturn is one thing that makes us wonder whether rings might exist around exoplanets, but of course in our own Solar System we also […]

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Dawn Orbits Ceres

March 6, 2015

I spent the morning working on an interesting paper about detecting ‘exorings’ — ring systems like Saturn’s around exoplanets — while switching back and forth to Twitter and various Web sources to follow events as the Dawn spacecraft became gravitationally captured by Ceres. I have problems with so-called ‘multi-tasking,’ which at least in my case […]

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Strategies for Life on Titan

March 4, 2015

Back in September of 1961, Isaac Asimov penned an essay in Fantasy & Science Fiction under the title “Not As We Know It,” from which this startling passage: …when we go out into space there may be more to meet us than we expect. I would look forward not only to our extra-terrestrial brothers who […]

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Seeing Ceres: Then and Now

March 2, 2015

I’m interested in how we depict astronomical objects, a fascination dating back to a set of Mount Palomar photographs I bought at Adler Planetarium in Chicago when I was a boy. The prints were large and handsome, several of them finding a place on the walls of my room. I recall an image of Saturn […]

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Soft Robotics for a Europa Rover

February 23, 2015

Approaching problems from new directions can be unusually productive, something I always think of in terms of Mason Peck’s ideas on using Jupiter as a vast accelerator to drive a stream of micro-spacecraft (Sprites) on an interstellar mission. Now Peck, working with Robert Shepherd (both are at Cornell University) is proposing a new kind of […]

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A Full Day at Pluto/Charon

February 13, 2015

Have a look at the latest imagery from the New Horizons spacecraft to get an idea of how center of mass — barycenter — works in astronomy. When two objects orbit each other, the barycenter is the point where they are in balance. A planet orbiting a star may look as if it orbits without […]

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