Vernal Equinox. At Machu Picchu this rock is called the “hitching post of the sun”—Intihuatana, to the ancient Incas, who celebrated the equinox at this site. Some bright mind among them determined that this day was a special one, and so he—or she—carved the 26-inch-tall stone so that it faces at a very particular northward angle—about 13 degrees, the latitude of Machu Picchu. The effect is that at noon on both the spring and fall equinoxes, for just an instant, the stone’s shadow disappears. The sun, so it seemed to the ancients, was at those moments “hitched” to the end of the stone.
