What was the longest year in history?

The ancient Roman origins of the leap year

The earth's orbit around the sun takes about 365.2422 days, leaving farmer almanacs the awful job of pretending the calendar year fits into a whole number. This article explores the modern origins of the civil solar calendar and its leap year. The Julian calendar, named after the Roman emperor Julius Caesar, cut the calendar year into 365.25 days, gifting the public an extra day every four years. Learn more of the history here.

January is named after Janus, the Roman god of transitions

In 46 BCE, Julius Caesar introduced the Julian calendar, which established Jan. 1 as the beginning of the new year. The month was named after Janus, the Roman god of transitions, who had two faces—one looking back at the past, the other forward to the future. While the Babylonians also made promises as part of their celebration of the new year, the Roman tradition became more focused on looking backwards to plan for the coming year.

The tradition of drinking Champagne on New Year's is believed to come from ancient Rome

Julius Caesar might not have had sparkling wine, but when the Romans created the now-standard calendar that begins on Jan. 1, they celebrated with a toast. The tradition spread throughout Europe and then the colonies, and so when Champagne became the drink of choice for special occasions, it was only natural that it became the standard New Year’s Eve sip.

What was the Great Fire of Rome?

In the hours between July 18 and 19 in 64 CE, the glittering capital of ancient Rome became engulfed in flames. This 46-minute podcast details the Great Fire of Rome that destroyed much of the city, according to historical literary sources. The fire burned for nine days after starting at market stalls near the Palatine Hill and the Circus Maximus, one of the city's largest chariot racing stadiums. The fire's cause remains unknown.

Twelve centuries of Roman history in 20 minutes

The Roman Empire may have been the world's first example of globalization, covering thousands of miles and crossing language barriers armed with Latin and short swords. Its legacy is nearly unparalleled in contemporary Europe, with nearly 50 Romance languages deriving from Latin.

Caesar's true betrayer wasn't Brutus but Decimus, a conspirator history forgot

It was Decimus—not Brutus—who was closest to Caesar, dined with him the night before his murder, and talked him out of skipping the Senate meeting on the Ides of March when Caesar grew suspicious. This article argues that in his play named after the Roman dictator, Shakespeare immortalized the wrong man. Decimus was captured and executed within two years; Brutus and Cassius took slightly longer to meet their ends.

The winter solstice has been celebrated globally for millennia

From gatherings at Stonehenge in the UK to celebrations of the triumph of Mithra in Iran, cultures around the world have marked the shortest day of the year in a variety of ways for a very long time. Here are eight known to us today that endure.

Why do humans have such long childhoods?

Humans have over twice as long childhoods than other animals with similar lifespans like whales and elephants. A human child can grow for nearly 20 years before they become a reproducing adult. Researchers believe there's a connection between long childhoods and human's unusually large brain size, though the science is not totally clear. Dive into what scientists know here.

The Year 2038 problem is the next potential computer time rollover bug

Many older systems store time as a signed 32-bit integer counting seconds since Jan. 1, 1970. That counter maxes out on Jan. 19, 2038—overflowing into negative time and sending clocks back to 1901, potentially crashing any older software that depends on accurate dates.

What summer was like the year you were born

Summers have generally grown warmer, so chances are the first summer of your life was cooler than the most recent one. Stacker used official average weather data for the months of June through August from the year 1920 to 2022 in this fun data dive.

Stanford built a Google Maps for the Roman Empire, revealing how much it cost to travel in the ancient world

See what it's like to live 'Constitutionally' for a year

In a 2023 interview on CBS Sunday Morning, author A.J. Jacobs discusses his attempt to live as closely as possible by the principles of the US Constitution for a whole year and the book that resulted from the experiment.

Modern presidential primaries now span months before conventions formalize nominees

In 2020, the major parties selected nominees through 64 primary and caucus contests held over 22 days. Until the 1960s, most nominees were chosen by party leaders at conventions rather than through widespread primaries.

Dangers of a record-breaking, sleep-skipping stunt

In 1963, 17-year-old Randy Gardner decided to stay awake for as long as it took to break the current world record. He managed to stay awake for 11 days. In 2017, the then-71-year-old Gardner told NPR that his experience had come back to haunt him as insomnia. The challenge has since been removed from the Guinness Book of World Records due to its dangerous consequences.

The 16th-century astrologer Nostradamus' predictions for 2024

Nostradamus has been credited with predicting several major historical events over the years, but what does he think is in store for 2024? Read up on what his mysterious 1555 book, The Propheties, hints at for the upcoming year.

July Fourth wasn't always a holiday, and its meaning has changed over time

This podcast explores how July Fourth evolved from an ordinary day into a national holiday, tracing its radical origins, the shifting interpretations of the Declaration, and how later generations claimed its language of liberty and equality.

Advent's length varies from 21 to 28 days each year

Because Advent always begins on the fourth Sunday before Christmas, its duration varies. When Christmas falls on a Monday, Advent is unusually short, and when it falls on a Sunday, it can be nearly four full weeks long.

Rising sea levels due to climate change may be slowing Earth's rotation

A 2024 PNAS study found that from 2000 to 2020, the length of a day increased at a rate of 1.33 milliseconds per century, an unprecedented amount in the 3.6 million years of day-length changes reconstructed from an analysis of benthic foraminifera fossils. Researchers suggest the slowing comes from changing ice sheets redistributing planetary mass.

In late 2007, Wikipedia became the world's largest general encyclopedia

The record had been held for approximately six centuries by the Yongle Encyclopedia, which was commissioned by the Yongle Emperor of the Ming dynasty in 1403 to preserve information from ancient and imperial China. The text comprised 22,937 manuscript rolls in 11,095 volumes.

The longest official chess game lasted 269 moves and over 20 hours

In 1989, Ivan Nikolić and Goran Arsović played a marathon 269-move match in Belgrade. Lasting more than 20 hours, the game ended in a draw.

The Lewis and Clark expedition lasted over two years

The Corps of Discovery departed St. Louis in May 1804 and returned in September 1806, covering more than 8,000 miles by boat, horseback, and on foot. See a timeline of the journey’s key events.

How much did WWII cost?

Though it lasted fewer than four years, World War II was the most expensive war in United States history, according to this infographic. Read through it to see how much WWII cost and learn about the consequences of financing such an expensive conflict.

Why pickles became a thing

Pickles began in Mesopotamia around 2400 BCE as a way to preserve vegetables amid heat (and spoilage). They spread through Egypt, Greece, and Rome, where Julius Caesar reportedly fed pickles to his soldiers, and brining was treated as a culinary art. The technique is broadly useful, as salt and water can extend the shelf life and deepen flavor for almost anything.

‘Guiding Light’ was the longest-running scripted drama in broadcast history

The show ran for 72 years, starting as a radio program in 1937, and eventually transitioning to television in 1952. Along the way, it launched several Hollywood stars, like Kevin Bacon, James Earl Jones, and Christopher Walken. CBS canceled the show in 2009.

Mariah Carey's 'All I Want for Christmas Is You' is the longest-running No. 1 single

In 2025, the 1994 track spent 20 weeks atop Billboard’s Hot 100 chart. The song has been a popular Christmas number since its release, but streaming has elevated it to a perennial chart-topper: Every time someone plays the song on a service like Spotify (something that’s likely to happen every holiday season), they’re effectively casting a vote for it to hit the chart.

During his 'miraculous year,' Einstein published four groundbreaking papers

The 1905 "annus mirabilis" papers explained the photoelectric effect, Brownian motion, the absolutism of the speed of light, and mass-energy equivalence, revolutionizing scientists' understandings of space, time, mass, and energy. For the discovery of the photoelectric effect, Einstein won the 1921 Nobel Prize in Physics.

The US Constitution is widely regarded as the longest-standing written national constitution still in force—see how it has influenced rights worldwide.

Meet the 56 signers of the Declaration of Independence—most of whom didn't put pen to paper until August 2, 1776—and see their original signatures.

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

For centuries, it was common to sleep in two shifts: a few hours at the beginning of the night, and a longer period beginning around midnight

The United States has had a tumultuous relationship with Cuba since its 1959 revolution, highlighted by a nuclear crisis and a decades-long trade embargo.

Abraham Lincoln was almost assassinated weeks before his inauguration as he traveled from Illinois to DC through Baltimore in 1861; it took two independent claims for Lincoln to be convinced the threat was real

Hear about the 250-year history of the United States Postal Service, complete with some of its strangest deliveries, important innovations, and the figures that made it an American institution.

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

The Russia-Ukraine conflict is the largest ground war in Europe since World War II in casualties, forces mobilized, and displacement of civilians.

El Niño, Spanish for 'the boy,' was named after Jesus Christ because the phenomenon resembled the weather changes observed around Christmastime.

Apeirophobia is an overwhelming fear of living forever, perhaps stemming from the brain's inability to conceptualize an infinite life.

Scientists testing how climate change affects plants found, in a years-long simulation study, that poison ivy grew 70% faster with the resulting extra carbon dioxide.

The term 'algorithm' originated from the Latinized name of al-Khwārizmī, a 9th-century mathematician whose works introduced Arabic numerals and the decimal-based numeral system to Europe and whose treatise 'Al-Jabr' gave algebra its name.

Double world record holder Hunter Ewen helped conquer his fear of balloons, called globophobia, by training to win Guinness World Record titles for balloon inflation.

Before writing 'Walden,' transcendentalist Henry David Thoreau nearly burned down his hometown with a campfire that grew out of control.

Watch a 1934 short film starring jazz legend Cab Calloway, a major figure in the Harlem Renaissance's music scene

Search a massive database of over 4 decades of clues from the TV quiz show 'Jeopardy!'

The most expensive ad of all time was for Chanel No. 5 perfume and cost roughly $33M to produce in 2004—about $57M in today's dollars.

Fireworks-related ER visits are on the rise—in 2024, they increased by 52% as compared to the prior year.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

The first line of 'immortal' human cells, which can divide indefinitely and are used in scientific research, was nonconsensually taken from a Black woman.

In preparation for this weekend's Eurovision finale, which is something like the World Cup of pop music, here's a young Céline Dion performing (for Switzerland?) at the 1988 competition.

Domino's Pizza's 30-minute delivery guarantee was responsible for the chain's 1980s surge, but it was discontinued after the company was found liable for delivery driver accidents.

The Mona Lisa's celebrity status and repeated restorations have obscured what made the painting so revolutionary for its time