In astronomy, a crescent is the shape of the lit side of a spherical body (most notably the Moon) that appears to be less than half illuminated by the Sun as seen by the viewer. Mathematically, assuming the terminator lies on a great circle, such a crescent will actually be the figure bounded by a half-ellipse and a half-circle, with the major axis of the ellipse coinciding with a diameter of the semicircle. The direction in which the "horns" (the points at the intersection of the two arcs)
face indicates whether a crescent is waxing (also young, or increasing) or waning (also old, or decreasing). Eastward pointing horns (pointing to the left, as seen from the Northern hemisphere) indicate a waxing crescent, whereas westward pointing horns (pointing to the right, as seen from the Northern hemisphere) indicate a waning crescent. Note that the directions the horns point relative to the observer are reversed in the Southern hemisphere.
On September 23 2014 at United States 6 Views
Digital camera : Nikon / Coolpix