An alternative conserved vector is the binormal vector B studied by William Rowan Hamilton, which is conserved and points along the minor semiaxis of the ellipse. (It is not defined for vanishing eccentricity.) The LRL vector is the cross product of B and L (Figure 4). On the momentum hodograph in the relevant section above, B is readily seen to connect the origin of momenta with the center of the circular hodograph, and to possess magnitude A/L. At perihelion, it points in the direction of the momentum. The vector B is denoted as "binormal" since it is perpendicular to both A and L. Similar to the LRL vector itself, the binormal vector can be defined with different scalings and symbols. The two conserved vectors, A and B can be combined to form a conserved dyadic tensor W, where α and β are arbitrary scaling constants and represents the tensor product (which is not related to the vector cross product, despite their similar symbol). Written in explicit components, this equation reads Being perpendicular to each another, the vectors A and B can be viewed as the principal axes of the conserved tensor W, i.e., its scaled eigenvectors. W is perpendicular to L , since A and B are both perpendicular to L as well, . More directly, this equation reads, in explicit components, See also Astrodynamics Orbit Eccentricity vector Orbital elements Bertrand's theorem Binet equation Two-body problem References Further reading Updated version of previous source. . Classical mechanics Orbits Rotational symmetry Vectors (mathematics and physics) Articles containing proofs Mathematical physics