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Geometry of the triple system of a star, a planet, and a moon. In the left panel the planet-moon duet has advanced by an angle ν
around the star, and the moon has progressed by an angle 2πϕps. The right panel shows a zoom-in to the planet-moon binary. As in the left panel, time has proceeded, and a projection of 
at time t=0 has been included to explain the orientation of the moon's orbit, which is inclined by an angle i and rotated against the star-moon periapses by an angle η.
