How the months of the year got named

The names of the 12 months are (mostly) derived from the Romans

January is named after two-faced Janus, February stems from a festival known as Februa, March comes from the god of war, Mars, and so on. Learn the origins and see ancient statues or art for the inspiration for each name of the month.

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 world's different calendars, explained

The calendar we use to mark the days, months, and year can feel set in stone, but the history of calendars shows these organization systems can and do change. Parse the fascinating, complex details of the Gregorian, Julian, Chinese, Hebrew, and many more calendars in this comprehensive, well-executed explainer video.

With the exception of Earth, the planets are named after Roman gods and goddesses

Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune are named after the messenger of the gods, the goddess of love, the god of war, the king of gods, the god of agriculture, the god of the sky, and the god of the sea, respectively. "Earth" comes from Old English and Germanic words meaning "ground."

How lunisolar calendars work

Despite being called Lunar New Year, the Chinese calendar that the holiday is based on is actually lunisolar, or based on both the sun and the moon. Many religious holidays—including Easter, Ramadan, Chinese New Year, and Passover—do not have fixed dates according to the now-ubiquitous Gregorian calendar.

China has used several different calendars because of changes in government structure

For many centuries, during which China was an imperial nation, the lunar/lunisolar calendar (aka the “rural calendar”) was the basis for organizing the year. Several attempts were made over the decades to switch to the Gregorian calendar—which begins Jan. 1—but it wasn’t until the People’s Republic of China was founded in 1949 that it stuck.

Meteorological v. astronomical seasons, explained

Meteorologists and climatologists define seasons differently from “regular” or astronomical spring, summer, fall, and winter. Traditional seasons reflect the movement of celestial objects, known as the astronomical seasons; meteorologists mark seasonal change based on temperature averages.

Some believe Valentine's Day evolved from the Roman holiday Lupercalia

The festival, which took place in mid-February, featured Roman priests sacrificing a goat and using its hide to lightly slap women and the land, believing it would bring fertility. Some believe that the Catholic Church repurposed the pagan holiday as a Christian one by attaching it to a saint, but scholars are not certain that this is true.

A year's name is determined by the 12-year Chinese zodiac cycle

According to Lunar New Year traditions, the coming year gets its name based on the 12-year Chinese zodiac cycle. The animals, in order, are rat, ox, tiger, rabbit, dragon, snake, horse, goat, monkey, rooster, dog, and pig. 2026 is the Year of the Horse, an animal known for its strength and momentum, while 2027 will be the Year of the Goat.

The scientific name for northern lights came from two Greco-Roman gods

Although cave paintings may have depicted them millennia earlier, one of the oldest known references to auroras is a Babylonian cuneiform tablet from about 600 BCE. In 1619, Galileo Galilei named the phenomenon in the northern hemisphere "aurora borealis" after the Roman goddess of dawn—Aurora—and the Greek god of the north wind—Boreas.

The Aztecs synced their solar calendar with a complex 260-day ritual cycle

Researchers have uncovered how the Aztecs aligned their agricultural solar calendar with a symbolic 260-day ritual calendar, utilizing celestial tracking and monuments. Evidence from ruins and writings explains why their new year corresponded to February 23 on the Gregorian calendar.

The hour originated from an ancient Egyptian astronomical system

The movements of astronomical objects, measured in a day and a year, form the foundation of our sense of time. The Egyptians divided each day and night into 12 time eras, using arbitrarily selected stars as references rather than movements of specific celestial objects.

What was the longest year in history?

In 46 BCE, Julius Caesar declared the year would last 445 days. This four-minute podcast and accompanying article explain why. Caesar wanted to make the following year start after the winter solstice, an achievement attainable due to his tinkering with the Roman calendar. But to start the year right, Caesar had to stretch the transitional year, leading to the creation of Caesar's Year of Confusion, the longest year in history.

How people imagine a calendar year

It turns out everybody imagines the abstract calendar year in a simple, concrete way, though there are surprising differences between the exact model and shape of each image. Dive into one writer's collection of tens of thousands of questionnaire responses showing the fascinating consistency and divergence of how people visualize time.

Saturnalia was a Roman festival that helped shape Christmas

Ancient Romans celebrated Saturnalia in mid-December, honoring Saturn, the god of agriculture, with week-long street festivals. These celebrations featured gift exchanges, lavish meals, and gambling, which was prohibited in public at the time.

Lunar New Year is celebrated around the globe

“Lunar New Year” is a catchall term that encompasses celebrations in several Asian countries. The date of the new year can vary by location depending on which calendar—lunar, lunisolar, or solar—is being used, but many of the traditions are shared across borders.

How the brain processes a calendar year

When most of us picture a calendar year, we have a foggy image in our minds of the months, in rough, calendar-like grids. But for some folks, that picture is a whole lot more clear. Around 1 percent of the population has a strange ability known as "calendar synaesthesia," which means they're able to visualize in crisp detail an elaborate calendar of the months of the year. Learn how it works here.

The American colonies recognized New Year’s Eve in March until 1752

England followed the Julian calendar, established by Julius Caesar, which had an inaccurate method of calculating leap years. Because of that, New Year’s Day eventually slipped into the spring and was linked with the Christian festival of the Annunciation, which was on March 25. That date carried over to the American colonies, which didn’t change the first day of the new year until 1752, after England adopted the newer Gregorian calendar.

The Atlantic Ocean was named after Atlas, who holds up the sky in Greek mythology, while the Pacific Ocean was named by Ferdinand Magellan.

Mardi Gras blends pagan celebrations with Christian traditions

The holiday has its roots in pagan celebrations, like ancient Rome's Saturnalian and Lupercalian festivals, which celebrated spring and fertility. Rather than abandoning these traditions, Catholic leaders in Rome incorporated their spirit into a celebration that would expel citizens' debauchery in preparation for the sacrifices they'd endure during the Lenten season. Around the world, this holiday season is called Carnival, though the New Orleans version is usually called Mardi Gras.

Valentine's Day's namesake is unclear

Valentine, which means "powerful" or "worthy," was a popular name in the Roman Empire. Considering that, it's no surprise that there's more than one St. Valentine. In fact, three different men named Valentine were martyred on February 14, and none of them, despite some unproven legends, were ever associated with love or romance.

Moon 101: NASA's complete overview of our lunar companion

From modulating our tides to impact our climate, Earth's lone natural satellite plays a key role forming the planet's habitat. Before diving into the rest of the resources on this page, check out NASA's overview of the basics of the Moon—how it got its name, its size and distance from Earth, its structure, and much more.

The history of the New Year's misunderstanding in England

In the mid-18th century, the legal system in England operated under the understanding that the New Year began March 25. However, the widespread custom remained a Jan. 1 celebration as the public had been practicing for years. Read along to discover the practical issues this discrepancy caused and how the English legal system ended up yielding to public belief.

The origins of British pub names

An estimated 50,000 pubs dot the streets and countrysides of Britain, many of which have histories going back centuries. This deep dive traces the origins of some of the most common pub names to the medieval era, including favorites Red Lion, Crown, and Royal Oak. Learn why such names were originally chosen and how they have come to evolve in recent centuries in this comprehensive overview.

Why we have different seasons

Visualize just how exactly seasons come to be with this animation of the earth in relation to the sun, and see how earth's tilt determines our seasons.

Bake bread like a Roman, and honor Ceres, the goddess of wheat

Grains made up about 70% of the Roman diet, and the word "cereal" stems from the goddess Ceres—the Roman equivalent of Greece's Demeter—to whom they prayed for good harvests. Cato the Elder, a famous statesman, left behind a simple home recipe for a Roman loaf.

Every tropical storm is named from one of six predetermined lists maintained by the World Meteorological Organization.

Learn how the Egyptians, Romans, and other ancient civilizations worshipped the sun

In Egypt, the pharaoh was seen as the living embodiment of the son of Ra, the sun god. In Mesopotamia, the sun god Shamash was a divine judge whose light could reveal the truth. Huitzilopochtli, the Aztec god of sun and war, was thought to require sacrifices to prevent the universe's destruction.

Advent marks the beginning of the church calendar in Western Christianity

Each denomination’s calendar of holy days varies, but most mark the start of a new year at the beginning of Advent. Within Roman Catholicism, Advent is a distinct period from Christmas, alongside other seasons: Ordinary Time, Lent, Easter, Holy Week, and Pentecost.

Asia's agriculture-focused set of 24 'small seasons'

In contrast to the four broad seasons and their basis in astronomy and climate, ancient farmers in China and Japan had many more and varied seasons (or "sekki). Take Keichitsu (March 6 to 21), for example: this means "going-out of the worms" when bugs come out from hibernation.

Why meteorologists say summer starts June 1

There are at least two periods called summer: astronomical and meteorological. Astronomical summer mirrors the movement of celestial bodies and begins roughly around June 20, with the summer solstice. Meteorologists designate the beginning of June as the start of summer to make tracking weather patterns from year to year easier.

For the medievals, the moon was a versatile religious symbol

Within the distinct traditions of Christianity and Islam, the moon became a central metaphor and sign for religious teaching. For Christians, its light was used to explain Jesus' humanity with the light of the sun (divinity). For Muslims, the moon represented a cosmic longing for god.

As of 2026, 14 of Neptune's 16 moons have been named for mythological figures, with Triton, the largest of them, orbiting backward, or in retrograde.

The Lunar New Year lasts 15 days, with specific rituals for specific days

On the first night, loved ones gather to celebrate their honor and say goodbye to the successes and tribulations of the old year. On the fourth day, the God of the Kitchen is honored to prevent kitchen accidents. And beginning on day 12, people prepare for the final Festival of Lanterns.

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.

The dark origins of Valentine's Day.

The holiday began as a feast to celebrate the decapitation of a third-century Christian martyr, or perhaps two. So how did it become all about love?

Although the moon passes between the sun and Earth each month, its orbit is tilted by five degrees, preventing Earth from experiencing a solar eclipse each month.

Ancient Greek told to kick rocks after claiming moon wasn't a deity

About 2,500 years ago, ancient Greek philosopher Anaxagoras theorized that the moon probably wasn't a goddess. This article explains how this belief led to his exile. Anaxagoras also argued the sun was just a burning rock, writing that it was the sun that illuminated the moon. According to this resource, this theory enabled Anaxagoras to accurately explain eclipses and lunar cycles.

The calendars of the 'Lord of the Rings'

JRR Tolkien's epic fantasy trilogy "The Lord of the Rings" is a seminal work in the history of literature partly due to its creator's obsessive focus on systematic detail—including the calendars used in the world. Take a fantastic dive into the minutiae of Tolkien's creation by learning the different approaches to time organization in the Shire or Rivendell with this dense, comprehensive resource based on Tolkien's appendices.

Galileo Galilei—considered the father of modern science—was once president of the Academy of Lynxes and used the name Galileo Galilei Linceo on the title pages of his works in its honor.

Grasp the earth's orbit around the sun with this interactive

See why seasons exist with this interactive simulator. Toggle between different views of the earth in relation to the sun and watch as the earth's axis causes the sun to shine at different angles throughout the year, causing the weather to fluctuate and more. This simulator clarifies a process many take for granted.

The science of springtime, 101

Dive into the basics on springtime including the astronomy that brings it about, natural signs of spring's arrival, and some of the cultural approaches to the season.

Galileo’s discovery of Jupiter’s moons led to multiple scientific advancements

Beyond challenging Earth-centric views upon their discovery in 1610, the Galilean moons were also later analyzed to contribute to early astrometry and astronomical interferometry. Measurements of eclipses were also used to estimate the speed of light.

Seven ancient ‘O Antiphons’—names for Jesus—are sung in the days before Christmas

The antiphons are prayers that express a profound longing for Jesus’ return and commemorate His birth. Each of the antiphons (for example, "O Emmanuel," the basis of the classic hymn) ascribes a different name to Jesus, like O Sapientia (“wisdom”) and O Rex Gentium (“king of the nations”).

Astronomers inferred Neptune's existence through mathematics while attempting to explain irregularities in Uranus' orbit, but Neptune had been directly observed 234 years earlier by Galileo.

New Year's Eve celebrations date back to ancient Babylon

Rather than celebrating in winter, the Babylonians honored the vernal equinox, a day in late March with equal amounts of darkness and light that signaled the start of a new year. They celebrated with Akitu, an 11-day festival.

Why some people say the moon is made of cheese

Mental Floss digs into the history behind the fable, which dates back as far as the 1500s, when it was mentioned in "The Proverbs of John Heywood." Even NASA has gotten in on the joke, tweeting a (supposedly) doctored photograph showing the moon's expiration date.

The Ancient Chinese harnessed solar power for heating and cooling 6,000 years ago

Neolithic Chinese homes faced south for winter sun warmth, while overhangs shielded them from high summer sun. These efforts also influenced urban planning, with cities aligning streets east-west for optimal solar exposure.

From the Greek for 'star taker,' the astrolabe allowed individuals to tell time and determine their latitude based on the position of the sun or other stars, as well as calculate the height of objects.