About me

Welcome to my blog!  I am an American astrophysicist living in Bordeaux (France) with my wife Marisa and our two sons. I study the formation and evolution of planetary systems.  In my research and on this blog I ask questions like:

  • Where did Earth’s water come from?
  • Which extra-solar planetary systems are the best for life?  and
  • Why does our Solar System appear to be different than planetary systems around other stars?

In this blog I try to balance imagination with science.  Sometimes I “play God” and design other planetary systems (for example, here and here).  Sometimes I evaluate the setting of science fiction stories (see here).  These designs are constrained by what kinds of systems could actually form and remain stable.  I also sometimes break out Dr Seuss-style astronomy poems (see here).

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Credit: Olivier Got – Université de Bordeaux

You are welcome to check out my research website, where you can find a summary of my research and a list of my publications.  Here is a talk I gave at Google a few years ago.  Here and here are talks I’ve given recently on planet formation (to somewhat technical audiences). I also enjoy giving talks to the general public (see for example, here and here).

In my spare time I enjoy hanging out with my wife Marisa and two sons.  I also play ultimate frisbee, hike, and do other silly things.

You can contact me directly by email at rayray(dot)sean(at)gmail(dot)com.

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18 thoughts on “About me

  1. Pingback: Building the ultimate Solar System part 5: putting the pieces together | planetplanet

  2. Hi Sean

    An excellent blog that I have really enjoyed reading.

    I have a few questions

    How small of a red dwarf star can an earth sized planet orbit and receive the same solar flux as the earth before it becomes tidally locked and Stellar winds from the star become a problem?

    Thanks Laintal

    • HI Laintal — good question.

      Check out this image: http://sites.psu.edu/ceh5286/wp-content/uploads/sites/4579/2014/04/revised_ZAMS_grayscale.jpg

      It shows how far away the habitable zone is (in grey) from its star for different kinds of stars (brighter stars are higher). To the left of the dashed line tides are strong enough to make a planet’s rotation locked so that it always shows the same face to the star. So this is important for stars as massive as about 60-70% the mass of the Sun.

      Being tidally-locked is not necessarily bad for life. None of the ideas about tidally-locked planets — flares, stellar winds, etc — have been shown to be “nails in the coffin” for such planets. I think they are still good candidates for life. What I think is worth worrying about is tidal heating on these planets, which is stronger the farther to the left of the dashed curve your planet is. But tidal heating depends in large part on the other planets in the system — it’s not just a 1-planet thing.

  3. Hi there,

    I just found your blog after reading your recent Nautil.us article (“Reading Earth’s Destiny in the “Blood Spatter” Around Other Stars”). Seems promising. As I’m not a trained scientist I hope I’ll find useful and understandable pieces of information here 🙂

    Thanks for sharing your work in this interesting field. I stay tuned via RSS syndication.

  4. Pingback: Did the Solar System form inside-out? | planetplanet

  5. Really love reading your blog’s! They get my imagination going and get my curiosity of other star systems and their planetary systems going. I have to admit, I may not quite understand all the physics (a long time out of classrooms and a lot of new theories since I studied!), but you have a great knack for explaining that truly helps. Keep up the great work!

  6. Great Blog! I found you doing research for my Sci Fi writing bug. I like your rogue planet theories and what they would look like.
    I have a question:
    In theory can there be a binary planet system where the two planets are lined up with their axis one atop another, like two spinning basketballs rotating the same direction together but not touching? The North and south poles would be opposite each other with the repelling force of magnetism offsetting the mutual pull of gravity. Instead of the common theory of Binary planets rotating around a center of gravity, mine would look like a dumbbell spinning on its axis. The ‘handle’ of the dumbbell being the offsetting forces of the pull of gravity and the push of the opposite poles.

    • Hi John, thanks for the question. Let me see — you basically want to use magnetism to offset gravity and create a binary planet. I don’t think this is plausible but I haven’t done the numbers. The magnetic forces involved would have to be titanic. Magnetic forces also require charge moving with respect to a magnetic field, so a static configuration wouldn’t work. It seems like an unstable equilibrium, even if you could get it to work. I can imagine magnetic forces playing a small role in a binary system, but relying on magnetism to counterbalance gravity seems like a very tall order… I’ll think more about this and I’ll get back to you if I have any more insights.

    • HI Jacob — thanks for asking. I am happy to let anyone use these ideas for science fiction of any kind. And I’m happy to help with any specific issues you might have to make a setting as plausible as possible (astrophysically speaking, of course).

  7. Thanks.
    My hypothesis is that the magnetism keeps a smaller body from circling the larger planet in an orbit. Rather, the larger planet captures the smaller and holds it in a stationary orbit over one of the poles. They would be very close to each other. Not necessarily sharing atmospheres but that would be interesting too. The down side of a common atmosphere would be, that being that close together, there would be a danger of tidal earthquakes.

  8. Hi Sean,
    I really enjoyed reading this. It is making complicated stuff easier for us to get our teeth into. Humans are great and we need to show our greatness more often. Thank you for showing yours – a guiding star you are!

  9. I’ve been trying to figure out how to build a solar system for a sci-fi project I am working on, but it’s been hard to find tools to help me understand the minutia. I found a video about a 2-star system (https://vimeo.com/115945369) which I used as a basis – with some modifications like only 1 planet orbiting the yellow star and no moons), and have tried to assign things to the orbiting planet like how long is a day, year, season, etc… I dig mechanical stuff like this, but I am so far out of my bailiwick that it’s more frustrating than fun. I want to get this sort of stuff as right as I can based on what science knows so far.

    Do you know of any software tools that will help me better model this sort of solar system and planetary orbits? Thanks!

  10. Pingback: The Black Hole Ultimate Solar System: a Supermassive Black Hole, 9 Stars and 550 Planets | Astronomers and Star Gazers

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