Winter Solstice 2018: 10 Facts About the Shortest Day of the Year

Matt Cardy/Getty Images
Matt Cardy/Getty Images

Amid the whirl of the holiday season, many are vaguely aware of the approach of the winter solstice, but how much do you really know about it? Whether you're a fan of winter or just wish it would go away, here are 10 things to note—or even celebrate—about the solstice.

1. IT HAPPENS ON DECEMBER 21 UTC THIS YEAR.

Sun setting behind a tree in the winter
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The date of the winter solstice varies from year to year, and can fall anywhere between December 20 and December 23, with the 21st or 22nd being the most common dates. The reason for this is because the tropical year—the time it takes for the sun to return to the same spot relative to Earth—is different from the calendar year. The next solstice occurring on December 20 will not happen until 2080, and the next December 23 solstice will not occur until 2303.

2. IT HAPPENS AT A SPECIFIC, BRIEF MOMENT.

sun setting through the trees
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Not only does the solstice occur on a specific day, but it also occurs at a specific time of day, corresponding to the instant the North Pole is aimed furthest away from the sun on the 23.5 degree tilt of the Earth's axis. This is also the time when the sun shines directly over the Tropic of Capricorn. In 2017, this moment occurs at 4:28 p.m. UTC (Coordinated Universal Time). For those of us on Eastern Standard Time, the solstice will occur at 11:28 a.m. on December 21. And regardless of where you live, the solstice happens at the same moment for everyone on the planet (you can check what time it will occur for you here).

3. IT MARKS THE LONGEST NIGHT AND SHORTEST DAY OF THE YEAR FOR THE NORTHERN HEMISPHERE.

sun setting over Central Park
iStock.com/rmbarricarte

As most are keenly aware, daylight hours grow shorter and shorter as the solstice approaches, and begin to slowly lengthen afterward. It's no wonder that the day of the solstice is referred to in some cultures as the "shortest day" or "extreme of winter." New York City will experience 9 hours and 15 minutes of sunlight, compared to 15 hours and 5 minutes on the summer solstice. Helsinki, Finland, will get 5 hours and 49 minutes of light. Barrow, Alaska, will not have a sunrise at all (and hasn't since mid-November; its next sunrise will be on January 22), while the North Pole has had no sunrise since October. The South Pole, though, will be basking in the glow of the midnight sun, which won't set until March.

4. ANCIENT CULTURES VIEWED THE WINTER SOLSTICE AS A TIME OF DEATH AND REBIRTH.

snow on tree branches
iStock.com/Eerik

The seeming death of the light and very real threat of starvation over the winter months would have weighed heavily on early societies, who held varied solstice celebrations and rites meant to herald the return of the Sun and hope for new life. Scandinavian and Germanic pagans lit fires and may have burned Yule logs as a symbolic means of welcoming back the light. Cattle and other animals were slaughtered around midwinter, followed by feasting on what was the last fresh meat for several months. The modern Druidic celebration Alban Arthan reveres the death of the Old Sun and birth of the New Sun.

5. THE DAY MARKS THE DISCOVERY OF NEW AND STRANGE WORLDS.

Pilgrims landing at Plymouth Rock
Hulton Archive/Getty Images

The Pilgrims arrived at Plymouth on December 21, 1620, to found a society that would allow them to worship freely. On the same day in 1898, Pierre and Marie Curie discovered radium, ushering in an atomic age. And on December 21, 1968, the Apollo 8 spacecraft launched, becoming the first manned moon mission.

6. THE WORD SOLSTICE TRANSLATES ROUGHLY TO "SUN STANDS STILL."

colorful sunset
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Solstice derives from the Latin scientific term solstitium, containing sol, which means "sun," and the past participle stem of sistere, meaning "to make stand." This comes from the fact that the sun’s position in the sky relative to the horizon at noon, which increases and decreases throughout the year, appears to pause in the days surrounding the solstice. In modern times, we view the phenomenon of the solstice from the position of space, and of the Earth relative to the Sun. Earlier people, however, were thinking about the Sun's trajectory, how long it stayed in the sky and what sort of light it cast.

7. STONEHENGE IS ALIGNED TO THE SUNSET ON WINTER SOLSTICE.

Stonehenge sunset
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The primary axis of the megalithic monument is oriented to the setting sun, while Newgrange, another structure built around the same time as Stonehenge, lines up with the winter solstice sunrise. Some have theorized that the position of the Sun was of religious significance to the people who built Stonehenge, while other theories hold that the monument is constructed along natural features that happen to align with it. The purpose of Stonehenge is still subject to debate, but its importance on the winter solstice continues into the modern era, as thousands of hippies, pagans, and other types of enthusiasts gather there every year to celebrate the occasion.

8. ANCIENT ROMANS CELEBRATED REVERSALS AT THE MIDWINTER FESTIVAL OF SATURNALIA.

Saturnalia parade
A Saturnalia celebration in England in 2012.
Christopher Furlong/Getty Images

The holiday, which began as a festival to honor the agricultural god Saturn, was held to commemorate the dedication of his temple in 497 BCE. It quickly became a time of widespread revelry and debauchery in which societal roles were overturned, with masters serving their slaves and servants being allowed to insult their masters. Mask-wearing and play-acting were also part of Saturnalia's reversals, with each household electing a King of Misrule. Saturnalia was gradually replaced by Christmas throughout the Roman Empire, but many of its customs survive as Christmas traditions.

9. SOME TRADITIONS HOLD THAT DARK SPIRITS WALK THE EARTH ON THE WINTER SOLSTICE.

Snowy woods
iStock.com/Serjio74

The Iranian festival of Yalda is celebrated on the longest night of the year. In pre-Islamic times, it heralded the birth of Mithra, the ancient sun god, and his triumph over darkness. Zoroastrian lore holds that evil spirits wander the earth and the forces of the destructive spirit Ahriman are strongest on this long night. People are encouraged to stay up most of the night in the company of one another, eating, talking, and sharing poetry and stories, in order to avoid any brushes with dark entities. Beliefs about the presence of evil on the longest night are also echoed in Celtic and Germanic folklore.

10. SOME THOUGHT THE WORLD WOULD END ON THE 2012 WINTER SOLSTICE.

snowy woods with sun through the trees
iStock.com/Delpixart

December 21, 2012 corresponds to the date 13.0.0.0.0 in the Mesoamerican Long Count calendar used by the ancient Mayans, marking the end of a 5126-year cycle. Some people feared this juncture would bring about the end of the world or some other cataclysmic event. Others took a more New Age-y view (literally) and believed it heralded the birth of a new era of deep transformation for Earth and its inhabitants. In the end, neither of these things appeared to occur, leaving the world to turn through winter solstices indefinitely, or at least as long as the Sun lasts.

A version of this story originally ran in 2015.

7 Facts About Blood

Moussa81/iStock via Getty Images
Moussa81/iStock via Getty Images

Everyone knows that when you get cut, you bleed—a result of the constant movement of blood through our bodies. But do you know all of the functions the circulatory system actually performs? Here are some surprising facts about human blood—and a few cringe-worthy theories that preceded the modern scientific understanding of this vital fluid.

1. Doctors still use bloodletting and leeches to treat diseases.

Ancient peoples knew the circulatory system was important to overall health. That may be one reason for bloodletting, the practice of cutting people to “cure” everything from cancer to infections to mental illness. For the better part of two millennia, it persisted as one of the most common medical procedures.

Hippocrates believed that illness was caused by an imbalance of four “humors”—blood, phlegm, black bile, and yellow bile. For centuries, doctors believed balance could be restored by removing excess blood, often by bloodletting or leeches. It didn’t always go so well. George Washington, for example, died soon after his physician treated a sore throat with bloodletting and a series of other agonizing procedures.

By the mid-19th century, bloodletting was on its way out, but it hasn’t completely disappeared. Bloodletting is an effective treatment for some rare conditions like hemochromatosis, a hereditary condition causing your body to absorb too much iron.

Leeches have also made a comeback in medicine. We now know that leech saliva contains substances with anti-inflammatory, antibiotic, and anesthetic properties. It also contains hirudin, an enzyme that prevents clotting. It lets more oxygenated blood into the wound, reducing swelling and helping to rebuild tiny blood vessels so that it can heal faster. That’s why leeches are still sometimes used in treating certain circulatory diseases, arthritis, and skin grafting, and helps reattach fingers and toes. (Contrary to popular belief, even the blood-sucking variety of leech is not all that interested in human blood.)

2. Scientists didn't understand how blood circulation worked until the 17th century.

William Harvey, an English physician, is generally credited with discovering and demonstrating the mechanics of circulation, though his work developed out of the cumulative body of research on the subject over centuries.

The prevailing theory in Harvey’s time was that the lungs, not the heart, moved blood through the body. In part by dissecting living animals and studying their still-beating hearts, Harvey was able to describe how the heart pumped blood through the body and how blood returned to the heart. He also showed how valves in veins helped control the flow of blood through the body. Harvey was ridiculed by many of his contemporaries, but his theories were ultimately vindicated.

3. Blood types were discovered in the early 20th century.

Austrian physician Karl Landsteiner discovered different blood groups in 1901, after he noticed that blood mixed from people with different types would clot. His subsequent research classified types A, B and O. (Later research identified an additional type, AB). Blood types are differentiated by the kinds of antigens—molecules that provoke an immune system reaction—that attach to red blood cells.

People with Type A blood have only A antigens attached to their red cells but have B antigens in their plasma. In those with Type B blood, the location of the antigens is reversed. Type O blood has neither A nor B antigens on red cells, but both are present in the plasma. And finally, Type AB has both A and B antigens on red cells but neither in plasma. But wait, there’s more! When a third antigen, called the Rh factor, is present, the blood type is classified as positive. When Rh factor is absent, the blood type is negative.

Scientists still don’t understand why humans have different blood types, but knowing yours is important: Some people have life-threatening reactions if they receive a blood type during a transfusion that doesn’t “mix” with their own. Before researchers developed reliable ways to detect blood types, that tended to turn out badly for people receiving an incompatible human (or animal!) blood transfusion.

4. Blood makes up about 8 percent of our total body weight.

Adult bodies contain about 5 liters (5.3 quarts) of blood. An exception is pregnant women, whose bodies can produce about 50 percent more blood to nourish a fetus.)

Plasma, the liquid portion of blood, accounts for about 3 liters. It carries red and white blood cells and platelets, which deliver oxygen to our cells, fight disease, and repair damaged vessels. These cells are joined by electrolytes, antibodies, vitamins, proteins, and other nutrients required to maintain all the other cells in the body.

5. A healthy red blood cell lasts for roughly 120 days.

Red blood cells contain an important protein called hemoglobin that delivers oxygen to all the other cells in our bodies. It also carries carbon dioxide from those cells back to the lungs.

Red blood cells are produced in bone marrow, but not everyone produces healthy ones. People with sickle cell anemia, a hereditary condition, develop malformed red blood cells that get stuck in blood vessels. These blood cells last about 10 to 20 days, which leads to a chronic shortage of red blood cells, often causing to pain, infection, and organ damage.

6. Blood might play a role in treating Alzheimer's disease.

In 2014, research led by Stanford University scientists found that injecting the plasma of young mice into older mice improved memory and learning. Their findings follow years of experiments in which scientists surgically joined the circulatory systems of old and young mice to test whether young blood could reverse signs of aging. Those results showed rejuvenating effects of a particular blood protein on the organs of older mice.

The Stanford team’s findings that young blood had positive effects on mouse memory and learning sparked intense interest in whether it could eventually lead to new treatments for Alzheimer’s disease and other age-related conditions.

7. The sight of blood can make people faint.

For 3 to 4 percent of people, squeamishness associated with blood, injury, or invasive medical procedures like injections rises to the level of a true phobia called blood injury injection phobia (BII). And most sufferers share a common reaction: fainting.

Most phobias cause an increase in heart rate and blood pressure, and often muscle tension, shakes, and sweating: part of the body’s sympathetic nervous system’s “fight or flight” response. But sufferers of BII experience an added symptom. After initially increasing, their blood pressure and heart rate will abruptly drop.

This reaction is caused by the vagus nerve, which works to keep a steady heart rate, among other things. But the vagus nerve sometimes overdoes it, pushing blood pressure and heart rate too low. (You may have experienced this phenomenon if you’ve ever felt faint while hungry, dehydrated, startled, or standing up too fast.) For people with BII, the vasovagal response can happen at the mere sight or suggestion of blood, needles, or bodily injury, making even a routine medical or dental checkup cause for dread and embarrassment.

You Can Now Go Inside Chernobyl’s Reactor 4 Control Room

bionerd23, YouTube
bionerd23, YouTube

The eerie interior of Chernobyl’s Reactor 4 control room, the site of the devastating nuclear explosion in 1986, is now officially open to tourists—as long as they’re willing to don full hazmat suits before entering and undergo two radiology tests upon exiting.

Gizmodo reports that the structure, which emits 40,000 times more radiation than any natural environment, is encased in what's called the New Safe Confinement, a 32,000-ton structure that seals the space off from its surroundings. All things considered, it seems like a jolly jaunt to these ruins might be ill-advised—but radiology tests are par for the course when it comes to visiting the exclusion zone, and even tour guides have said that they don’t usually reach dangerous levels of radiation on an annual basis.

Though souvenir opportunists have made off with most of the plastic switches on the machinery, the control room still contains original diagrams and wiring; and, according to Ruptly, it’s also been covered with an adhesive substance that prevents dust from forming.

The newly public attraction is part of a concerted effort by the Ukrainian government to rebrand what has historically been considered an internationally shameful chapter of the country's past.

“We must give this territory of Chernobyl a new life,” Ukraine's president Volodymyr Zelensky said in July. “Chernobyl is a unique place on the planet where nature revives after a global man-made disaster, where there is a real 'ghost town.' We have to show this place to the world: scientists, ecologists, historians, tourists."

It’s also an attempt to capitalize upon the tourism boom born from HBO’s wildly successful miniseries Chernobyl, which prompted a 35 percent spike in travel to the exclusion zone earlier this year. Zelensky’s administration, in addition to declaring the zone an official tourist destination, has worked to renovate paths, establish safe entry points and guidelines for visitors, and abolish the photo ban.

Prefer to enjoy Chernobyl’s chilling atmosphere without all the radioactivity? Check out these creepy photos from the comfort of your own couch.

[h/t Gizmodo]

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