Actually, the sun does not trace an exact path on its way back to the equinox or solstices as you might be thinking. Look up the term “analemma” to see that the sun traces a figure 8, if you will, on the earth’s annual path around our star. It is possible that the alignment only truly lights up the full emblem on the ground at the 11th hour of 11/11.
According to the text, it lights up the emblem at precisely 11:11 AM.