Location: South Pole
Weather: -28C, wind 5 kts

The summer solstice marks the middle of the warm - or should we say bearable - season here at the South Pole.  Although the average temperature will keep rising for another week or so, we have reached the point of time when the sun heads down again for the first time since June.  It's high noon at the pole! 

To put it in physical terms, the Earth has reached the point in its orbit around the sun where the southern end of its rotational axis has the maxmum inclination towards the sun.  "The southern end of the rotational axis" is by definition the South Pole, so you might say that this is the day when the pole points as much towards the sun as it will ever do during a year.  As seen from the ground, the sun has culminated in its path across our southern sky, having reached an elevation of roughly 23,5 degrees above the horizon.

What is unusual about the South Pole, is that the sun stays at that elevation the whole day.  It does not rise in the morning, nor go down in the evening - it merely circles the horizon at the same elevation throughout the 24 hours. But from today it will start a slow descent towards winter and obscurity, gradually spiralling down until it finally goes below the horison in late March. That sunset, at the autumnal equinox, is the only one at the South Pole next year. At other latitudes the equinox is when days and nights are equally long; at the South Pole it is when the day ends and the night begins. Sunrise comes 6 months later!  On the North Pole the situation is completely reversed, so anyone up there now will be right in the middle of an equally long night.

To have the sun circling about the horizon at the same elevation throughout the 24 hours is quite a novel experience. There is no temperature drop towards the evening, and it doesn't get any warmer in the morning.  What time of the day it is, is simply a matter of choice, as the sun is alway to the north. The station operates on New Zealand for practical reasons, but might just as well have chosen US east coast time, or Norwegian time, or any other time zone.  It makes no difference. Indeed there are people here working at all hours, and to those coming off a shift we could say "dinner time - coming soon to a timezone near you!".

For us, there is no point in getting out to take pictures in the evening or morning light, and we have to remember our sunnies even when getting out in the middle of the night. Whether it's daytime or nighttime, the 22nd or 23rd, we are still rouhly at noon, in the middle of this very long and only day at the SP, the day that started in September and ends in March.  We hope to be home before dusk!

The South Pole at 13.30 (left) and 23.30 today, NZ time.  Photo: Stein Tronstad/NPI