; equations for planet design
; used by Jerry Pournelle for science fiction books

; i illuminence, L luminosity, R distance to earth,
; M stellar mass, P period, all relative to sol/earth

; basic equations
i = L / R^2
M P^2 = R^3

; values for a particular story
i = 0.97
L = 0.93
M = 1.2
; exclude extreme values of P, R
1e-10 < P < 1e10
1e-10 < R < 1e10