## Surface Escape Velocity

2.38 km/s

'assuming g - 6.672 x 10-11 m3 kg-1 s-2; mass ratios are more accurate".

values of S and C are given in Table L-7. In terms of S and C, the distance to the center of the Earth for h=0 is d2=¿(S2 + C2)+ | ( C2 - S2)cos2\$ L.4 The Moon

The physical and orbital properties of the Moon are summarized in Table L-8. Additional general characteristics are given in Tables L-2 and L-3. To determine the Moon's visual magnitude, V(at any distance and phase, let R be the observer-Moon distance in AU and £ be the phase angle at the Moon between the Sun and the observer. Then

where the phase* law, P(Q, for the Moon is given in Table L-9 [Allen, 1973], For additional details and a sample computation, see Section 3.5. Note that the visual magnitude of the Moon at opposition (i.e., full Moon) at thé mean distance of the Moon from the Earth is —12.73.

Table L-9. Phase Law and Visual Magnitude of the Moon

(OEG)

P(t>

V (R. t) - V (R, 0>

(OEGI

P(t>

V(R.t)-VtR.O)

0 0