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19 October, 1999

When did the sun set last night where you live? I went to bed early last night and I set my alarm for 12:00Midnight NZDT so I could set the sun set over the Ross Sea. By the time I got outside, the sun was just below the northern horizon as I looked toward Mt. Discovery over McMurdo Sound. (See picture below.) Yes, I said midnight and I said northern horizon. That wasn't a typo. Remember that I'm in the Southern Hemisphere. I am also located within the Antarctic Circle. The movements of the sun in the sky at this location are much different then in North America. The sun goes below the horizon about midnight and only stays below the horizon for a short time. You can see a sunset and a sunrise within a couple hours of each other. The reason I wanted to get out last night and see the sun below the horizon is that by the end of the month, the sun will remain above the horizon all day. We will have 24 hours of sunlight.

Of course, in the middle of the austral (Southern Hemisphere) winter there are days when the sun does not go above the horizon. Now, that does not mean that is dark all day. In fact, much of the day may be quite light with twilight or dusk. I found an excellent diagram on the Internet that helped me understand when it gets light and dark at McMurdo Station. (See below) Along the bottom it shows the months of the year. Along the left side it shows the hours of the day. With this diagram I can figure out what the sunlight conditions will be for any time of the year in McMurdo. For example, at the middle of July, the sun never went above the horizon (no sunlight) but it was twilight from about 8AM until about 6PM. Right now in McMurdo we have about 22 hours where the sun is above the horizon. From about 11PM to 1AM the sun just dips below the horizon and we have dusk. That is why I had to get up at midnight to see the sun below the horizon. When will I not be able to see the sun set at all?

The fact that it is light here all the time causes some problems. At 10:00PM, when I normally go to bed (and I am very tired from working hard all day), it is very bright and sunny out. So you are very tempted to just stay up. This does benefit the work here for some things because work can be done at anytime of the day because there is plenty of light. It's harder to keep on schedule. In McMurdo, the regular mealtimes help you organize your day. At night, when you want to go to sleep, there are specially built window covers that attached with Velcro that keep the light out. You can make it night any time you want. So far, this has worked very well. I have slept very well at night. Well, except last night when I wanted to see the one of the last sunsets I'll see for a while.

It was warm again today, 21F. The wind wasn't too bad, gusting to 30MPH. The lowest wind-chill we had today was -20F. I hope this warm weather continues. It was also sunny today, so I got a great shot of my shadow. I'll share that with you tomorrow. Did you find out what "solar noon" is?

The sun below the Northern Horizon at 1AM NZDT on October 19.

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