The Sun is directly overhead of the Tropic of Capricorn in the Southern Hemisphere during the December Solstice. The December Solstice occurs when the Sun reaches its most southerly declination of -23.4 degrees. In other words, when the North Pole is tilted furthest away from the Sun.

What happens during solstice?

On two moments each year—what are called solstices—Earth's axis is tilted most closely toward the sun. The hemisphere tilted most toward our home star sees its longest day, while the hemisphere tilted away from the sun sees its longest night. ... (That's as far north as you can go and still see the sun directly overhead.)

What happens during the solstice on the Northern Hemisphere?

At the summer solstice, the Sun travels the longest path through the sky, and that day therefore has the most daylight. When the summer solstice happens in the Northern Hemisphere, the North Pole is tilted about 23.4° (23°27´) toward the Sun. ... The day has also been celebrated in many cultures.