A model of the brightness of moonlight

In this paper, measurements of the sky brightness from the 2800-m level of Mauna Kea are reported. In addition, a model is presented for predicting the moonlight as a function of the moon's phase, the zenith distance of the moon, the zenith distance of the sky position, the angular separation of the moon and sky position, and the local extinction coefficient. The model equations can be quickly calculated on a pocket calculator. A comparison of the model with lunar data and with some Russian solar data shows the accuracy of the predictions to range from 8 percent to 23 percent.