In HBO’s gory, sword-porn epic Game of Thrones (based on the novels by George R.R. Martin), the seasons are all out of whack:  summer lasts a decade, and everyone’s always ominously intoning that winter is coming. Most fans just shrug and accept the rules of the fantasy universe, but one dedicated group of Johns Hopkins graduate students has taken things a bit farther:  they’ve come up with an astronomical justification for the weird weather, complete with charts, equations, and footnotes.

Put simply, the students argue that the story must take place on a circumbinary planet — that is, a world that orbits two stars instead of one.

Put in a more complicated way — well, here’s an excerpt:

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For simplicity [ed:  ha!], we assume the three bodies are coplanar, the mass of the planet is negligible and its axis is not tilted. At each time step, we compute the distance from the planet to the two stars and, using the black-body approximation, calculate the equilibrium surface temperature of the planet by:

where Tp is the equilibrium surface temperature of the planet, AB is Bond albedo of 0.3 and greenhouse warming due to presence atmosphere of 30 degrees (see clouds, dragon smoke, Section 1.3), R1 and R2 are the two stellar radii (each equal to 1.RSun), T1 and T2 are the two stellar effective temperatures (both equal to 6000K) and r1 and r2 are the two instantaneous distances from the planet to each of the two stars.

Read the whole paper here, if you are so moved.