Solid angle at an average angular diameter of 0.5334 degrees or 9.310 radians. The Moon is seen from Earth at an average angular diameter of 9.22 radians. We can substitute these into the equation given above for the solid angle subtended by a cone with apex angle : The resulting value for the Sun is 6.807 steradians. The resulting value for the Moon is 6.67 steradians. In terms of the total celestial sphere, the Sun and the Moon subtend "fractional areas" of 0.000542% (Sun) and 0.000531% (Moon). On average, the Sun is larger in the sky than the Moon even though it
Degrees of freedom (statistics) the vectors of residuals are constrained to lie in a space of smaller dimension than the number of components in the vector. That smaller dimension is the number of degrees of freedom for error, also called residual degrees of freedom. Perhaps the simplest example is this. Suppose are random variables each with expected value μ, and let be the "sample mean." Then the quantities are residuals that may be considered estimates of the errors "X" − μ. The sum of the residuals (unlike the sum of the errors) is necessarily 0. If one knows the values of any "n" −