Is there a 6 month day and 6 month night in Antarctica?

Only at or close to the South Pole will there be 6 months of daylight, and nearly 6 months of night.

The Earth is tilted on its axis with respect to the plane of its orbit. The ends of that axis, the poles, must be either tipped toward the Sun, or tipped away from the Sun. As the Earth spins, the pole facing the Sun is always in sunlight, and the pole facing away has none. Only 1/2 of a planet can be illuminated at a time, and except on one day twice a year, the North Pole and South Pole are never both in daylight. At the equinoxes, the Sun may be visible from both poles.

When Antarctica is tipped toward the Sun (approximately September 21 to March 20, summer in the Southern Hemisphere), the Sun is up continuously, circling the horizon. Beginning on March 21, the sun does not rise above the horizon until the following September.