Day 3 of the conference saw several talks on spin-orbit misalignments and mean-motion resonances in exoplanetary systems.

Among the talks on spin-orbit misalignment, Josh Winn of MIT gave an excellent review of observational and theoretical developments in the field. He argued that any model to explain the misalignments must account for (1) the fact that 75% of hot Jupiters show significant misalignment, (2) misaligned systems are found preferentially around stars hotter than 6100 K, and (3) misalignments out to 10 days orbital period. Hefty requirements that no theory for misalignment has convincingly satisfied yet.

In the resonances session, Konstantin Batygin of Caltech gave a sparkling talk on his recent work looking at the establishment of resonances in planetary systems. He showed how effective resonance capture requires fairly small orbital eccentricities, less than about 0.02. His results could help explain why so many multi-planet systems are very near but not quite in resonance.

A quick update on day 3 of the IAU conference.

Good talks today on recent developments in our understanding of planet formation by Christophe Mordasini. Improved models for the dynamics of grains in the accretion streams for growing gas giants have helped solved some of the mysteries associated with the planets’ formation.

Aurelian Crida gave a very informative talk on developments in planetary migration. Turns out that migration can be very complicated.

And some good talks on the dynamics of mature planetary systems. Christa Van Laerhoeven reviewed classical secular theory and discussed how the orbital architectures of some systems can be determined, even in the absence of detailed information about the planets’ orbits.

Day 2 of the IAU meeting was very busy, with lots of great talks and presentations. Two events, in particular, stood out to me, though.

The first was a session on Highlights from Space Missions, which had a focus on results from the Dawn and Rosetta missions.

The Dawn mission visited the asteroid Vesta and is currently in orbit around Ceres, the largest asteroid in the asteroid belt and a world in its own right. By way of highlighting the recent results, the mission PI, Prof. Chris Russell, presented breath-taking images and movies from the mission. I’ve included some below.

The first movie is of a bright mountain on the surface of the asteroid Ceres called The Pyramid.

The second movie shows Occator crater with its mysteriously bright central … thing. The Dawn mission team is speculating that the bright spot is some kind of exotic salt deposit, based on its reflectance spectrum, but they’re not really sure what it is yet.

Next up, Dr. Sierks showed highlights from the the Rosetta mission, which is visiting Comet 67P and dropped the Philae lander last year onto the comet’s surface, also with mind-blowing movies.

The first movie shows the comet’s rotation, revealing its voluptuous  shape.

The next movie shows how the comet’s rotation causes its jets to curve, as the icy vapor escapes into space.

And the final movie (poorly focused unfortunately) shows the cosmic snow erupted into interplanetary space by the comet’s jets. These particles actually represent a hazard to the spacecraft and make it difficult for its operators to orient the spacecraft since they use background stars to figure out how it’s oriented. As a result, the spacecraft was moved to a more distant, safer orbit after these images were collected.

In the evening, IAU hosted an event at which they invited the public to vote on names for 20 known exoplanet systems.  Just since last night, the number of votes has gone from zero to more than 15,000.