Noah Kalendar
a. June 21
b. December 21
c. March 21
d. March 21 or September 21
The Answer is:
Noah arrived in Washington, D.C. on the equinox. During the course of the year, any prominence on the Earth will cast a unique daily shadow tip path as a function of the time of the year. On the equinox (vernal or autumnal), the Earth’s axis is not tilted toward the Sun (its axis is in a plane perpendicular to the plane containing the Earth and Sun), thus the shadow tip path of the Washington Monument is flattened to a straight line. The rest of the year the Earth’s axis has a varying tilt toward or away from the Sun that results in a prominence casting a shadow tip family of curves (resulting from conic intersections—circles, ellipses, parabolas or hyperbolas). These curves become concave upward after the autumnal equinox through the winter and then flatten to a straight line on the vernal equinox and then become concave downward through the summer flattening to a straight line with the return of autumn in the northern hemisphere. The seasonal effect on the shadow tip path is illustrated in Figure 43 .
