Alien planets and cephalopodoids

The latest issue of Science has a fascinating article on Exotic Earths—it contains the results of simulations of planet formation in systems like those that have been observed with giant planets close to their stars. The nifty observation is that such simulations spawn lots of planets that are in a habitable zone and that are very water-rich.

(click for larger image)

Final configuration of our four simulations, with the solar system shown for scale. Each simulation is plotted on a horizontal line, and the size of each body represents its relative physical size (except for the giant planets, shown in black). The eccentricity of each body is shown beneath it, represented by its radial excursion over an orbit. The color of each body corresponds to its water content, and the inner dark region to the relative size of its iron core. Orbital values are 1-million-year averages; solar system values are 3-million-year averages. Note that some giant planets underwent additional inward migration after the end of the forced migration, caused by an articial drag force. This caused many hot Earths to be numerically ejected, but had little effect outside the inner giant planet.

Dynamics of Cats has a better summary than I could give, and it leads in with this lovely illustration of an hypothetical alien organism on one of these hot water worlds.


The only thing cooler than a cephalopod has to be a tentacled alien cephalopodoid. There’s a high-res version of that image at Dynamics of Cats—and I’ve got a new desktop picture.

Molecular machines!


If you’ve ever wondered what the heck Behe was smoking when he claims there are literal trucks trundling about on literal highways with literal traffic signals inside of cells, well, I don’t have an answer for you…but there is a wonderful Flash movie that will show you the Inner Life of a Cell so you can see what “molecular machines” look like, more or less. It’s a spectacular show. What you’ll see is the series of events that transpire when a lymphocyte encounters a cell surface signal that triggers emigration out of a capillary and into other tissues; it zooms rather abruptly from a cellular view to the molecules on the surface interacting with one another, then into the interior of the cell to see the response. All kinds of cool stuff fly by: actin and microtubule assembly and disassembly, kinesin-mediated vesicle transport, protein synthesis on ribosomes, ER processing, vesicle fusion, etc.

I do have a couple of gripes, though. One is an understandable shortcut: the cell is far too uncluttered, and events proceed in too directed a manner—there ought to be much more stochastic noise at the molecular level. We’re seeing chemistry in action, after all. Another is that there is no explanation at all for anything we’re seeing, it’s simply a weird and trippy voyage into a subcellular world. This clip was created under the auspices of Harvard scientists, so I hope there is a viewing guide somewhere, otherwise it’s only going to be appreciated by people who have already read Molecular Biology of the Cell(amzn/b&n/abe/pwll). I think it also needed a disclaimer somewhere that this video too is a visual metaphor for cellular activity.

But I’m being picky. Otherwise, it’s an excellent introduction to the profound weirdness of the processes going on inside a cell.