I waited nearly my entire life for today.
There is a single point on a planet where the sun is directly overhead, where the sun is at its zenith. But, the sub-solar point is always at the latitude of solar declination. Consequently, the sub-solar point is always between the Tropic of Cancer and the Tropic of Capricorn. I have never lived in the tropics. So, I have never experienced an overhead sun. Until now.
All of Ghana is between the tropics, and Accra is at about 6 north latitude. (It is nearly on the Prime Meridian, too, but that is beside the point.) So, on the day when the solar declination is about 6 (early Spring in the Northern Hemisphere), the sun should be directly overhead Accra at high Noon. As it happens, today is that day, and the sub-solar point passed through Accra for an instant. (One can use the Sun Position Calculator to create a polar plot of the solar trajectory for any location. I verified today’s situation in Accra.)
To celebrate, Catherine and I took a photo on our patio. Unfortunately, clouds occluded the sun at Noon. At 12:32, we snapped the photo below. While not quite perfect, the sun is nearly directly overhead Catherine. There is almost no horizontal displacement to her shadow! Anyway, this is much closer to solar zenith than we ever get in Michigan!
Another item checked off my astronomical bucket list.
—Matt
