Radiation pressure causes a runaway increase in this quantity for small astronomical bodies according to the YORP effect. In the Kepler problem, the centrifugal term of the effective potential is proportional to the square of this quantity, (15[1])a fact which is derived by using this quantity to eliminate the (*) rotational velocity in the expression for the total energy. The definition of the Laplace-Runge-Lenz vector includes a term equal to the momentum crossed with this quantity. Kepler’s equal area law (10[1])is equivalent to the conservation (10[1])of (10[1])this quantity, which is always conserved by central forces. For 10 points, name this vector quantity defined as the cross product of position and momentum. ■END■