Science

A moment of global darkness on December 6

A moment of global darkness on December 6

The moment of global darkness—for the largest percentage of the human population on Earth—falls at 7:56 p.m UTC on Tuesday, December 6, 2022 Surprised? Consider that China and India are the 2 most populous countries on Earth. And both will be in the dark at that time. Meanwhile, America, New Zealand and much of Australia will be bathed in sunlight. Now consider that North and South America combined only appear about 13% global population. Picture over Timeanddate.com.

This article was originally published by Konstantin Bikos and Graham Jones on Timeanddate.com on December 1, 2022. Reprinted here with permission. Edit EarthSky.

A moment of global darkness

For just a moment on December 6, nearly 9 out of 10 people around the world will simultaneously experience the night.

A few months ago, our number crunchers checked (and partially confirmed) the online claim 99% of the world’s population receives sunlight at 11:15 UTC July 8. This left us wondering: What about the opposite situation? At what exact moment do most people experience night?

Like last time, we fed our computers with the time and date I call the date for 2022 and population data from Center for International Earth Science Information Network at Columbia University. We then calculated population data for day, night and three phases of twilight for every minute of every day of the year.

Here’s what we found out.

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December 6: Most people at night

According to our calculations, the moment of maximum darkness occurs at 19:56 UTC on Tuesday, December 6, 2022. At that time, the sky will be completely dark for about 85.92% of the world’s population. At that moment, night reigns over the three most populous continents: Asia, Africa and Europe (with very few exceptions).

How can it be a night for almost everyone?

As at any other time, the Sun will illuminate one half of the globe on December 6 at 19:56 UTC. The other half will be dark, and the people living there will experience night.

The reason so many people will be in the dark is because the most populated areas of the world will be on the night side of the Earth at that time. This includes almost all of Asia, which is home to approx 60% of all people.

Meanwhile, America, New Zealand and much of Australia will be bathed in sunlight. However, even though these are huge land areas, relatively few people live there. North and South America together make up only about 13% of our world population.

Two twilit runners-up

Although for most people it is the night of December 6th, there is also the case that December 21st and 27th are considered alternate moments of maximum darkness.

You see, our computers spit out December 6th as a result only when we ask them to adhere to the strictest definition of night. This definition says that the sun must be at least 18 degrees below the horizon.

If the angle is less than 18 degrees, it is twilight. It is the time in the morning and evening when indirect sunlight somewhat illuminates the sky.

December 27: It looks like night for most people

The point is that the darkest of the three phases is twilight, astronomical twilight, barely discernible from the night. The sun is between 12 and 18 degrees below the horizon during that twilight phase. And the sky is so dark it seems like night.

When we allowed our algorithms to include astronomical twilight, they calculated 19:39 UTC on Tuesday, December 27, 2022, as the moment of greatest darkness.

According to our figures, 86.11% of the world’s population experiences either nocturnal (85.23%) or astronomical twilight (0.88%) at that moment.

That’s about it Another 15 million people compared to the number we calculated for December 6. However, it hardly moves the needle on a global scale: the difference is only 0.19% of the world’s population.

December 21: Most people without direct sunlight

Another alternative moment of greatest darkness takes into account all phases of twilight, incl nautical and civil twilight. During those two phases, the sky is noticeably brighter. However, it still exists no direct sunlight.

Applying this loose definition of darkness, we arrive at Wednesday, December 21, 2022 at 21:44 UTC, the moment when most of us are not in the daytime.

We calculated that it affects 88.14% of the world’s population. Almost 9 out of 10 people on Earth!

Flat world map with darkness over the eastern hemisphere.
When considering not only the night, but all the phases of twilight, 9:44 p.m UTC On December 21, 2022, it puts 88.14% of the world’s population in the dark. Also keep in mind that the moon is close a new phase and won’t add much light to the night. Picture over timeanddate.com.

What is so special about those dates?

We were not particularly surprised that all the dates fall in northern winter. Most people live north of the equator, and December is the month when the least amount of sunlight reaches the northern hemisphere.

But why does the number of people in darkness (or quasi-darkness) peak on those dates? Why does night affect more people on December 6th than, say, December 5th?

It all depends on how much the shape of the region affected by night and twilight overlaps with the most populated regions in the world. That shape changes very little from day to day as the sun moves south before the December solstice and north again after the solstice.

On the dates we found, it simply matches the contours of the world’s population centers a little better than the day before or after.

But again, the difference is very, very small. Case in point: According to our calculations, the number of people who experienced the night at 19:56 UTC on December 6 is 6,665,450,571; exactly 24 hours earlier, that’s 6,665,326,866. That’s a difference of 123,705 people, a small margin globally.

Finding the exact minute

As for the time of day when most people experience darkness, it is basically when Asia, Africa and Europe are on the night side of the Earth.

At that time of year, it happens every day at 19:00 UTC. At that time, night had just fallen in Europe. It is also when the first rays of the sun of the new day have not yet reached the far east of Asia.

That said, you’ve probably noticed that the time we calculated for December 21st (21:44 UTC) doesn’t match. This is because the inclusion of nautical and civil twilight makes for a larger geographic area. An area that now stretches all the way from Japan in the east to some of North America’s most populous metropolitan areas, such as New York and Montreal, in the west.

As you can see in the screenshots of our site Day and night ticketit is only when the two brightest twilight phases are engaged that any significant portion of the North American population joins the “dark side.”

Wherever you are, enjoy the dark sky!

If this sounds too bleak and you can’t wait for the days to get longer again, let’s sweeten the deal. See how dark the skies are this time of year.

If the weather cooperates, wrap up warm and head outside to enjoy the spectacular Geminids meteor shower. At its peak on December 14-15, we expect about 150 shooting stars per hour.

A few days later, 22-23 Ursids meteor shower peaks, bringing us about ten meteors per hour.

And while you’re waiting for the shooting stars to fly across the sky, you can use ours Map of the night sky to spot planets and stars. Also, find more stargazing events at EarthSky Guide to the night sky.

Take it with a grain of salt

While we’re confident in our calculations and datasets, determining how many people experience the night at any given time is a pretty messy business.

First of all, world population is not static. It changes over time, and in some locations it does so at a different pace than in others. We’ve based our calculations on the latest reliable population data we could find, but it’s from 2020.

Moreover, the margins are small. While our algorithms identified a specific moment when most people experience nighttime, they also gave us many other dates and times during the Northern Hemisphere winter with nighttime populations that are only a fraction smaller. We are talking about several tens of thousands of people. Peanuts compared to world population.

Conclusion: On December 6, the largest percentage of the human population sees a moment of global darkness.

Via timeanddate.com



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