How to use: Earth Viewer: Click on any point on the earth to see the sky at midnight for the date listed. Disantance (fov angle): Field of View, or relative distance from the starfield. Has a range from 20 to 180 degrees Show Constellation Lines: When Selected, the blue constellation guide lines are displayed. Show Constellation Names: When Selected, the red constellation names are displayed. Use New Constellations: When Selected, the new Constellation lines and names are displayed. Buttons: Click on the buttons to increase/decrease the date by the ammount shown. You can also increase/decrease the starlight intensity detail of the starfield. Date: (internal date) Sun and Earth Viewer: Shows current tilt and orientation of the earth relative to the sun (white circle)