1) Click on link 2) Click the box for Earth/Moon 3) Click the box for 90 degrees 4) Move speed to slowest (farthest left) 5) use the left and right controls for "hourly" (farthest left button for hourly and middle button for hourly) 6) Watch the red star. Notice when the red star is directly facing the sun, the hour in the top left of the picture says "12". Keep clicking the hourly button to make the Earth rotate. Notice when the red star is facing directly away from the sun the hour says "0", meaning it is midnight and the day is starting over.