99% of Earth's population to experience light from sun at once on Saturday

Once in a while, viral memes and outlandish Reddit claims turn out to be true.

In 2022, a claim circulated on social media asserting that, on July 8, 99% of the world’s population would experience daylight or twilight simultaneously; in other words, only 1% of the world’s population would be located where it was nighttime.

Sounds a little far-fetched, right? It turns out the rumor is true.

EarthSky.org crunched the numbers. At 11:15 Universal time, or 7:15 a.m. Eastern time, on July 8 each year, about 96% of the planet’s population is bathed in at least a bit of sunlight. An additional 3% is in “astronomical twilight,” which occurs when the sun is below the horizon but its glow still illuminates a patch of thesky. This means, 99% of Earth’s nearly 8 billion residents will be on the sunlit side of Earth at the same time. July 8 turns out to be the day that most people around the planet experience daylight at the same time.

This occurs because most of Earth’s population lives on one side of the planet. It might not look like that on most maps, but that’s because the majority of classroom maps are distorted to be population-centric. In reality, the Pacific Ocean occupies virtually half of Earth. When it’s nighttime there, it’s daytime for almost all of Earth’s land masses.

Time of year plays a role, too. In December, January and February, the sun’s most direct rays shine on the Southern Hemisphere, which is home to only 10% to 12% of the world’s population. That leaves most of the Northern Hemisphere with indirect sunlight, cutting back on how long the daylight hours stretch.

If you’re looking to maximize the population enveloped in sunshine, the sun should be shining most directly on where nearly 90% of the world’s population lives — the Northern Hemisphere. That’s why the phenomenon occurs near when the Northern Hemisphere is experiencing its longest day at the summer solstice. There are actually many days that feature the 99% magic. Common sense dictates that, if one of the dates (July 8) is 17 days after the solstice, another should be 17 days before.

But, according to EarthSky, there are actually 60 days that surround the summer solstice and meet the 99% criterion. Between May 18 and July 17, there are a couple of minutes each day when 99% of Earth’s population is on the sunny side, so to speak. The timing just fluctuates about the 11:00 Universal time slot.

One might surmise that the solstice would spread sunlight to the greatest number of people, but that actually happens July 8. By then, a bit of the Northern Hemisphere’s sunlight has been trimmed away and nudged into the northern fringes of the Southern Hemisphere, resulting in a net gain in people on the sunny side. More people live just south of the equator than near the North Pole, so it turns out that’s the ideal date for maximizing the

simultaneously sunlit population.

Suffice to say, sometimes boggling statistics aren’t magic — they’re just often overlooked. And, as daylight dawns on the Eastern Seaboard on Saturday, people glancing skyward can know that, for an instant, nearly the entire world is experiencing something together.