Skyjinks: No sunset on Sunday, but last one until August on Monday – why is the sun so confused?

weirdsunrise

Separating day from night is trickier in Longyearbyen than the rest of the world most of the year as it is, but the coming week is one of those biannual occasions when the sun messes with our minds more than usual by defying the basic concepts of sunrise and sunset.

The three-and-a-half months of 24-hour daylight begins in Longyearbyen next Monday (although technically the city entered 24-hour twilight before actually seeing the sun for the first time early last month, one of many oddities to be explained shortly). The sun will rise at 1:20 a.m., a mere 48 minutes after the last sunset at 12:32 a.m.But here’s where thing get murky: the first day of the year without a sunset is Sunday. The sun rises at 1:58 a.m. and…just wanders around the sky for the rest of the day.

Such oddities tend to happen when the polar summer or polar night sets in – there will be one sunset and two sunrises when the polar summer ends on Aug. 25 of this year, for example – in keeping with official day/night designations that frequently have little to do with the reality of looking out the window to determine if it’s light or dark.

The first official sunrise in Longyearbyen this year was Feb. 16, for example, but the city didn’t “see” the sun for the first time until March 7 (normally it’s May 8, but leap year jumped in) – and most of the town didn’t come out of the shadow for another week or two – due to the surrounding mountains. But technically Longyearbyen entered 24-hour twilight on March, although it took astronomical skills to get of glimpse of those rays.

The city did have about 13 hours of useable light when it celebrated the annual “return of the sun” festival a few days later and there’s been 24 hours of light since April 5. But even when 24-hour days before official there will still be “unofficial” sunrises and sunsets many places most days due to those pesky mountains.

And when the sunsets begin again in August the nights set in with a vengeance: about two hours Aug. 25, three hours Aug. 26 and more than five hours by the end of the month. The next polar night begins Oct. 26, with the final few “days” winding down as quickly as they ramped up.