You can use it to determine the position of the sun, sunrise and sunset times as well ass moon position and rising and setting for any location on earth on any date and at any time.
Today, I am walking to a marmot den area and it's in an ess-curved coulee. (I was in 4 times last summer and they were not out?!) The steep cliffs are in shade til sometime after noon. Using The Photographer's Ephemeris to check the aspect of the sun, I know there is no sense in arriving before 2 PM ... closer to 3 PM would be better.