Torus geometry in the equatorial and meridional planes for Case 1 (a, b) and Case 2 (c, d), where geometries are represented with red curves. The horizontal black solid line is the Sun–Earth line. The blue lines on the equatorial and meridional plots have angular extents of φ_hw and φ_hh, respectively, about the Sun–Earth line. In this example, φ_hw = 40° and φ_hh = 12°. In Case 1, R₀ = 7.6 and a = 6.2, making the aspect ratio 1.23. In Case 2, R₀ = 11.1 and a = 6.9, making the aspect ratio 1.6.