Advent, Bioluminescence, and Black Friday Ads

What is Advent?

Advent—from "adventus," the Latin word for “arrival”—is a season of observance that forms part of the annual liturgy (or public worship) of many Christian denominations. Generally spanning the four weeks leading up to Christmas, the tradition emerged in fourth-century Christian communities in Western Europe and is observed by both the religious and as part of the secular holiday calendar.

Early forms of observance—especially in Gaul and parts of Spain—focused on both the Incarnation (or birth of Christ) and the Second Coming of Christ, core tenets of the Christian faith. The season was marked by a penitential attitude, in contrast to contemporary expressions of cheer. Varying regional differences converged into a standard tradition during the Middle Ages, which more closely linked the season to the Christmas story.

Today, Advent is observed with church attendance and the lighting of Advent candles on wreaths—one candle each Sunday, often associated with spiritual virtues like hope and joy, traditions established by Lutherans in 19th-century Germany. Beyond religious observance, the modern season is also defined by Advent calendars—many mass-marketed—that count down the days to Christmas.

... Read what else we learned about the season here.

Also, check out ... 

> A German town transforms its city hall into one big Advent calendar. (More)

> How "O Come, O Come, Emmanuel" became a beloved, haunting holiday hymn. (More)

> Chanel's 2021 luxury Advent calendar faced backlash for retailing at $825. (More)

> Early observance was less about cheer, more about fasting. (More)

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How bioluminescence works

Bioluminescence is the process by which an organism produces its own light due to a chemical reaction. It is sometimes mistaken for biofluorescence, the re-emission of absorbed light in a new color.

Though commonly associated with fireflies and glowworms, the phenomenon is rare in land species. By contrast, an estimated 75% of all ocean animals exhibit this ability themselves or through a symbiotic relationship with bioluminescent bacteria, which they use for self-defense, hunting food, mating, and communication.

The light comes from binding oxygen to one of several molecules called luciferin. Different species have different luciferin varieties, producing various types of oxyluciferin, a light-emitting molecule, in the reaction. The variety of oxyluciferin results in the variety of observed bioluminescent colors.

Scientists have used bioluminescent proteins to create tools to observe cellular biological activity and identify biochemical signals within cells for drug discovery.

... Read our full explainer on the phenomenon here.

Also, check out ... 

> How humans have used bioluminescence as a military advantage. (More)

> See a photo gallery of bioluminescent creatures. (More)

> Watch shrimp escape predators by releasing bioluminescent chemicals. (More)

> Scientists and artists paired up to create art from bioluminescence. (More)

Who are the Rockefellers?

The Rockefeller family is one of the wealthiest families in American history, with influential legacies in business, art, architecture, and philanthropy. John D. Rockefeller, born in 1839 into relatively modest circumstances, became the world’s first billionaire in 1916 after creating the first major business trust. By some accounts, he is still the richest man to have ever lived. Their cumulative net worth today is $10.3B. 

The Rockefellers created the Standard Oil Company, which contributed to innovations in scaled business practices (namely, through trusts) amid the Industrial Revolution in the US, catalyzing a shift toward market centralization and monopoly. They've also financed American institutions such as New York City's Rockefeller Center, Colonial Williamsburg, and more.
 

Their modern-day influence mostly involves charitable giving to causes like higher education, the environment, and national parks. Their moneyed reputation has outlasted John D. Rockefeller himself: Taylor Swift, for instance, recently referenced the Standard Oil fortune in a popular song.

... Read our full write-up on the family here.

Also, check out ... 

> See Rockefeller Center's Christmas trees since 1931. (More)

> The Rockefellers funded the restoration of Colonial Williamsburg. (More)

> How Standard Oil used vertical integration to grow their business. (More)
> John D. Rockefeller's father was a well-known con artist. (More)

Best of the Week

We've added 180 resources this week to our knowledge collective—here are some of our favorites.

Explore 25 years of Black Friday ads. 

The wild museum-like relics you can find in a Macy's in California.

Why the fall is the best time of year to buy a car.

The forgotten carnivals that once stood upon the frozen River Thames.

See how the Winter X Games course is built. 

How Fidel Castro launched a revolution on a small yacht in December.

Earth is actually colder when it's at its closest point to the sun.

Hear firsthand stories from Americans who lived through the 1918 flu pandemic.

Mark Twain was an early influence on stand-up comedy.

Santa Claus originally wrote Christmas letters instead of receiving them.

Why are there sinkholes?

Medieval European winters were colder than ours, but peasants stayed warm.

Explore a visual history of the Windows operating system.

The 2012 Maya-predicted apocalypse didn't really stem from the ancient Mayans.

Unlike other bears, polar bears do not hibernate. 

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Historybook: Holy Roman Emperor Otto II ends the siege of Paris (978); Preliminary Treaty of Paris, ending the Revolutionary War, signed (1782); Woody Allen born (1935); London's Crystal Palace destroyed by fire (1936); Billy Idol born (1955).