Where do you have to be on Earth to see the south celestial pole at your zenith? What is the maximum possible elevation (angle) of the Sun above the horizon at that location? On what date is this maximum elevation achieved?
In order to see the south celestial pole at your zenith on Earth, you need to be at the geographic South Pole. The South Pole is located at latitude 90 degrees south.
The maximum possible elevation or angle of the Sun above the horizon at the South Pole depends on the time of year. At the summer solstice, which occurs around December 21st, the Sun can be as high as 23.5 degrees above the horizon. This is because the Earth's axis is tilted towards the Sun during this time, causing the Sun to reach its highest point in the sky.
On the other hand, at the winter solstice which occurs around June 21st, the Sun is at its lowest point in the sky at the South Pole, and it does not rise above the horizon at all. This means that there is no daylight at the South Pole during this time of year.
So, the maximum possible elevation of the Sun above the horizon at the South Pole is 23.5 degrees, and it is achieved around the summer solstice.