The sun has set, and we are past the equinox, when the tilt of Earth's axis has no component in the direction of the sun. At the equator, the sun passes directly overhead during the equinox. At the poles, the sun is exactly halfway setting on the horizon. Although, that's not exactly what we see. Due to atmospheric refraction the sun will remain visible for days, perhaps much longer than a week. Exactly how long the sun remains visible is unpredictable... Temperature and weather impact the refractive index of the atmosphere, and with so much atmosphere to pass through to reach us while the sun is at the horizon, the visible effect is sensitive and variable. The sun may disappear entirely only to return again, purely due to changes in the atmosphere.
The long, slow spiral of the sun downward means that twilight will last for well over a month. It won't be until late April that we experience astronomical twilight, the time when the sun is far enough below the horizon (>12 degrees) that most stars become visible. Until then, the suns rays still hit enough of the upper atmosphere, scattering light and obscuring many of the visible stars. And it will not become fully dark until nearly mid-May.
And yes, the sun really does go around us in perfect circle (it is technically in an imperceptible spiral down to the horizon). Being located directly at the geographic south pole, we literally have one day and one night in an entire year. And when you take a 24 hour time lapse, you get to see the sun pass horizontally across the sky in faster-than-real-time. It's pretty neat.