And a related topic you didn't ask about, for a suitably distant observer of both the earth and the moon, both would show the same phase at the same time. One of the Mars orbiting spacecraft took a picture of 'the home world' a while back that showed this. Also Cassini, I believe, did a time lapse of the moon passing across field of view showing earth and it also verified this. Very neat pictures, and a neat way of looking at phases. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>