- This figure shows the Earth-Moon system looking down on the North Pole of the Earth. The sun, which is not shown, is located towards the bottom of the figure. The first quarter Moon is located at -90 degrees, (position D, above) the full Moon is located at 0 degrees (between positions B and C, above) and the third quarter Moon is located at +90 degrees (position A above). The Terra spacecraft maneuver(s) to enable instruments to view the Moon should be restricted to lunar views in which the lunar phase (i.e. the Sun-Moon-Earth angle) is between -4 and -90 degrees or between +4 and +90 degrees, as shown in the figure.
