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Daylight, or perhaps the lack of it, is on our minds at this time of year.

Here is a column I wrote for today on the topic. One thing that occurred to me afterward was how artificial lights obscure the need to see what we can see at twilight. An idea for another day.

Yes, the sun rises late and sets early this time of year, creating light conditions that are one of the joys of the season.

I know this runs counter to the constant refrain from Outside — “How can you stand it being dark all the time?”

But the sun that hugs the horizon, crawling across the southern sky, floods the landscape with orange and yellow hues not seen on summer days when the star of the show has more staying power.

Some people pay little attention to the winter sun and bemoan the brief period between sunrise and sunset. They are quick to remind our friends Outside that the sun will rise at 10:57 a.m. and set at 2:39 p.m. today, bathing this part of Alaska in about 3 hours and 42 minutes of daylight.

But those official figures give the wrong impression. It’s not as if daylight goes on and off like one of Mr. Edison’s inventions. It more like a room with a celestial dimmer.

It operates with a subtle touch, giving denizens of the planet time to adjust from dark to light.

The twilight hours are an important element of life in Alaska. They give us far more freedom to see what is around us than is conveyed by official daylight statistics. And that’s not counting the light that reflects off the snow after dark.

We are closing in on the winter solstice, which takes place Sunday at 3:04 a.m. At that point, the sun will be at its southern extreme for the year, the longest day of the year on the other side of the world.

Those who live to the north of us, beyond the line known as the Arctic Circle, 23.5 degrees south of the North Pole, will receive no official daylight, but a healthy dose of twilight. In Fairbanks, the sun will peak at 2 degrees above the horizon at “solar noon,” which occurs shortly before 1 p.m., thanks to Alaska time zones that are never in sync with the sky above.

During most of our December daylight, the sun is either rising or setting.

When it is barely above the horizon, its rays traverse, on average, 13 times more air than when the sun is high in the sky, according to an account by Bob Berman in Astronomy magazine.

“This causes nearly all of its blue light to scatter out, leaving only the longer wavelengths. That’s why the setting sun is orange,” he said.

The times of sunrise and sunset published in this newspaper are derived from a computer program in which sunset is defined as that moment when the upper edge of the sun is level with the horizon.

For purposes of the computer program, the horizon is considered to be flat, when viewed from any particular point on the earth, and the observer’s eye is considered to be at ground level, according to the U.S. Naval Observatory. The daylight statistics, therefore, convey an impression of precision that is not justified in fact.

Earth is not flat, and the horizon is not ordinarily viewed from ground level.

There is a precise definition of twilight — the time after sunset until the center of the sun is 6 degrees below the hypothetical horizon. Twilight is to begin this morning in Fairbanks at about 9:32 a.m., almost 90 minutes before sunrise.

It continues about 90 minutes after sunset, when you can still see your hands in front of your face.

The light in those periods is reflected, produced by rays of the sun that shine from below the horizon and light up the sky above.

The duration of twilight depends upon local weather conditions, but the computer program comes close, the observatory notes on its Web site.

Berman writes that 24 minutes of twilight is typical in the tropics and its average is about 36 minutes in Seattle.

As the darkness builds, civil twilight gives way to nautical twilight, which ends when the sun drops 12 degrees, and the horizon is too dim to see. Astronomical twilight follows, ending with the sun 18 degrees below the horizon.

“Thanks to twilight’s slow pace, we rarely sense how dim the light has become,” Berman said of this daily progression, visible when you get away from artificial light.

“Photochemical changes in the eyes, pupil dilation from 2.5 to nearly 7 millimeters and the shift to scotopic rod-cell vision make the transition so smooth, we’d never guess that ambient illumination during early astronomical twilight has grown 500,000 times dimmer than when the sun was shining.”

Scotopic vision is night vision, a phenomenon of low light, when the eye can distinguish brightness, but not colors.

All of which is to say that there will be light today before sunrise and after sunset.

If you have a column suggestion or a comment, contact me at cole@newsminer.com or 459-7530.