FIG. 2.

Comparison between the Tinetti et al. (2006a, 2006b) model (old model, gray) and our new model (black). A measure of Earth's reflectivity, taken as π times the disk-integrated radiance (in W/m²/μm/sr) divided by the solar flux at 1 AU (in W/m²/μm), is shown for the planet viewed at full phase, gibbous phase, quadrature (i.e., half illuminated), and crescent phase, or, alternatively, phase angles of 0°, 45°, 90°, and 135°, respectively. Both models use realistic cloud cover, and the data for the old model is taken from the left column of Fig. 6 in Tinetti et al. (2006b). EPOXI observations taken at phase angles of 57.7° and 76.6° (dashed gray) and our model of the observations (dashed black) are shown in the gibbous and quadrature cases, demonstrating that our model correctly reproduces the brightness and spectral shape of the data at these phases. In general, the Earth model from Tinetti et al. (2006a, 2006b) is about 100–400% too bright and is too blue at phases near quadrature and crescent. Earth views generated by the Earth and Moon Viewer, first implemented by J. Walker (http://www.fourmilab.ch/cgi-bin/Earth).