Look up the date of any Islamic holiday going back to 622 CE

Ramadan will be celebrated twice in 2030 due to the 33-year lunar cycle

Because the Islamic year is 11 days shorter than the Gregorian calendar, Ramadan migrates through every season over a 33-year cycle. In 2030, it will fall twice in the same Gregorian year.

A 101 on why Ramadan is the holiest time of the Muslim year

As a spiritual guide for members of the Brandeis University community, this overview surfaces the highlights to orient readers on Ramadan logistics, practices, and obligations. It's a useful start for those interested in learning the basics around fasting rules, exemptions, the significance of iftar and suhoor, and common greetings.

How to sight the new crescent moon that starts Ramadan

Ramadan doesn't begin on a fixed date. Instead, it begins when a crescent moon is visually confirmed. The Royal Museums Greenwich explains the astronomy behind the sighting, including the conditions that must be met: the sun must be below the horizon, the moon must be above it, and the two must not be within the Danjon Limit (roughly 5 to 7 degrees of separation in the sky, as shown below).

Muslims fasting in Iceland face more than 20 hours of daylight during summer Ramadan

In countries near the Arctic Circle, Ramadan's rule of fasting from sunrise to sunset can cause some unique challenges for the extended periods of daylight in the region. Icelandic Muslims have developed pragmatic workarounds—some follow the hours of Mecca, others adjust locally. It's an edge case that illuminates how a 7th-century practice gets negotiated across radically different geographies.

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.

Nearly 70% of Muslim Americans always donate to charity during Ramadan

Zakat, one of the core pillars of Islam, directs Muslims to redistribute their wealth and give to the poor. This pillar is commonly honored during Ramadan and likely motivated by the practice of fasting, which encourages gratitude and compassion for those who are less fortunate. Other spikes in charitable giving are seen during the holiday of Eid al-Adha and at the end of the financial year.

Laylat al-Qadr: the single Islamic night 'holier than a thousand months'

Toward the end of Ramadan, Laylat al-Qadr is observed, recalling Muhammad's "night of power" when the Quran was first revealed, according to Islamic tradition. The Quran describes it as better than a thousand months of worship. Its exact date differs between Sunni and Shia adherents, falling on the 27th night of the month for Sunnis and the 23rd for Shias.

UK's Royal Astronomers join the hunt for Ramadan's crescent moon

In Britain, Muslim communities and professional astronomers now collaborate to officially spot the moon that begins Ramadan, blending ancient practice with modern science. The partnership culminates in a live, unscripted annual broadcast even.

Visa data shows Muslim spending spikes at night during Ramadan

Fasting during the day reschedules economic activity to the night. Visa's spending data shows a surge in Muslim-majority markets during Ramadan at night as restaurants and retailers orient themselves around iftar. The pattern has become a significant target for advertisers and brands.

Iftar foods from around the world

The global population of Muslims eats and fasts in distinct way around the world. This photo survey spans Morocco's harira soup to Indonesia's kolak (a sweet dessert soup) and Turkey's pide (like pizza but without the tomato sauce). The one universal aspect for most iftar meals is dates and water, following Muhammad's practice. (Some users may experience a paywall.)

Ramadan moon-sighting can spark intra-family disputes

Because different communities—and even different members of the same family—follow different methods for confirming the crescent, Ramadan doesn't always start on the same day for everyone. The result: "moon wars" that pit parents against children, and mosques against each other, on when exactly the fast begins.

The Five Pillars of Islam, explained through Islamic art at the Met

Fasting during Ramadan—known as sawm—is one of five foundational practices that define Muslim life. The Met uses art objects to illuminate the pillars to make the theology more tangible. Ramadan's fast is interwoven with this broader framework of prayer, charity, pilgrimage, and expressions of faith.

Eid ul-Fitr vs. Eid ul-Adha: differentiating the two lesser and greater Eids

Most non-Muslims associated Eid with the end of Ramadan—but that's actually the lesser Eid. The greater one, Eid ul-Adha, comes 70 days later and commemorates Ibrahim's (Abraham) willingness to sacrifice his son. It involves Qurbani, the ritual slaughter of an animal, with meat distributed to those in need.

A readable narrative account of how Muhammad first received the Quran

The story behind Ramadan's origins involves a lesser-known layer of personal drama for Muhammad, who fled the Cave of Hira in fear thinking he had been possessed by the angel communicating with him. Only his wife, Khadijah, was able to reassure him. The first revelation came during Ramadan in 610 CE, but the full Quran took 23 years for the angel Jibril (or Gabriel) to deliver.

Hanukkah is one of 8 major Jewish holidays

This calendar, maintained by the Reform Judaism organization, not only shows when each holiday is to be celebrated in the current year, but also includes short histories and common rituals.

Ramadan tends to reduce Gulf productivity, but increases reported happiness

Economists have documented a measurable dip in productivity and output in Muslim-majority countries during Ramadan. But surveys consistently show the opposite on subjective well-being, with people reporting they feel better and more connected.

The Hajj

A diary of fasting through all 30 days of Ramadan

Aramco World's first-person account follows one Muslim through a full month of fasting—the pre-dawn suhoor meal, the hunger wall, the social texture of iftar. Get a sense of the day-to-day of Ramadan with this experiential guide.

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.

How Eastern Orthodox and other Christians celebrate Easter differently

Western churches switched to the Gregorian calendar in 1582, though the Orthodox Church still calculates Easter using the Julian calendar, which runs 13 days behind. Orthodox Easter also must always follow Jewish Passover. The result is two Easters that can fall up to five weeks apart.

Why Easter's date changes, making it a 'moveable feast'

Unlike Christmas, Easter has no fixed date: It falls on the first Sunday after the first full moon on or after March 21, a formula set by the Council of Nicaea in 325 CE to form a standard across Christianity. The result is a window of 35 possible dates, from March 22 to April 25.

Tarawih: the special night prayers during Ramadan

Beyond fasting, Ramadan nights have their own distinct ritual: Tarawih, an extended voluntary prayer performed after Isha, the standard final of five daily prayer times. Communities read through the entire Quran over the course of the month alongside these Tarawih prayers.

A virtual tour of the Hajj pilgrimage

Over 2 million pilgrims travel to Mecca, Saudi Arabia, every year during the Hajj pilgrimage, a central tenet of the Islamic faith. The route traces one the Prophet Mohammed is said to have once walked, and involves challenging rituals including...

Ramadan is a major television event in the Middle East

Each year, major networks air special 30-episode dramas timed to the month—one episode per night after iftar. Syrian productions long dominated the format, though that has shifted. The season is the advertising event of the year across the Middle East, rivaling the Super Bowl in commercial intensity.

In 1995, Hakeem Olajuwon won NBA Player of the Month while fasting

When Ramadan began on February 1, 1994, Olajuwon fasted every day of the month while playing for the Houston Rockets. He still won Player of the Month. His story is a fascinating look on how world-class athletes stay competitive while observing their religious obligations.

Explore an interactive diary of the International Space Station

The tool enables users to learn about the daily events that occurred on the ISS since continuous human occupancy began on November 2, 2000. Upon selecting a date in the calendar, users can explore activity logs, relevant news, and multimedia content, including videos, photographs, and audiologs, from the onboard crew.

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.

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.

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.

A 12-minute crash course on Islam, its beliefs, and history

John Green's Crash Course World History episode overs Islam's core tenets, the Five Pillars, and the religions spread across continents in a jam-packed video under 15 minutes. The video is an efficient on-ramp for newcomers and is an ideal starting point to Islam.

Calibrate to the U.S. government's official clock, synchronized to the atomic standard

The site displays the current time across all American time zones—corrected for network delay—and shows whether your device's clock has drifted. Computer clocks rely on quartz crystals that drift slightly with temperature and age, requiring alignment with atomic clocks (which are so stable that seconds are defined by them).

How the months of the year got named

Curious about how the months got their names? This article from The Old Farmer's Almanac explores the origins of today’s Gregorian calendar. Based on the ancient Roman lunar calendar, the months were named after Roman gods until winter when the names changed to numerical titles. Read along to learn the significance and intentions behind labeling each lunar cycle.

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

Visualize your city’s annual daylight map

Type in your town or region and see sunrise and sunset for each day of the year. A separate view shows the number of hours of day versus night for each day. Search a city far north like Oslo, Norway, and compare its graphs to one near the equator (like Singapore).

Check out hurricane history where you live

The NOAA's historical hurricane tracker lets you explore over 150 years of data to see where hurricanes traveled and made landfall. The tool lets you search by location, name, or year; create maps and tables; and read NOAA storm reports.

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.

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.

The 1979 Iranian Revolution inspired other Islamist movements and alarmed Sunni governments

By establishing the world's first modern Islamic theocracy, the revolution inspired Islamist movements across the region and alarmed Sunni Arab governments. The resulting rivalry between Shia Iran and Sunni Saudi Arabia has since fueled proxy conflicts in Lebanon, Iraq, Syria, and Yemen that persist today.

Historically, cholera has repeatedly disrupted the Hajj for Muslims

Outbreaks of the disease throughout the 19th century and the beginning of the 20th, killed thousands of religious pilgrims as they sought to complete this obligatory pilgrimage.

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.

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 to eat for suhoor, the pre-dawn mean that has to last all day

Suhoor—eaten before the Fajr prayer at dawn—is the only fuel a fasting Muslim has until sunset. This practical guide covers the logistics around what foods sustain energy longest, what to avoid, and why hydration strategy matters as much as what you eat.

Mapping the Middle East showing Sunni and Shia populations by country

France24's interactive visualization shows where each branch of Islam predominates across the region, from Iran's Shia majority to Saudi Arabia's Sunni dominance. The map helps make Middle Eastern politics (and conflicts) more legible.

Explained: The Year of the Rabbit

One of the world's largest holidays, this visual guide will help you welcome the Year of the Rabbit and celebrate the new lunar year.

By identifying patterns in the periodic movements of the sun, moon, and Earth, ancient civilizations realized that identical eclipses repeat about once every 6,585 days, known as the saros cycle.

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.

Early timekeeping tools included sundials, water clocks, and astrolabes

Astrolabes also provided a person's latitude based on the height of the stars in the sky, thus aiding in navigation. Incense and candle clocks relied on the constant burning rate of fire to track the passage of time based on premarked locations with equal-interval spacing.

Watch the many different civilizations around the Mediterranean shift power from the year 2500 BCE to 0 BCE in this animated map.

Hanukkah wasn’t always a major Jewish holiday

In the 1800s, Jewish immigrants to the United States began searching for ways to maintain their cultural identity in an overwhelmingly Christian environment. Because Hanukkah often falls around the same time as Christmas, Jewish congregations began adapting Christmastime traditions like gift giving to their own holiday.

Smaller companies’ IPO information can be hard to track down

This calendar keeps you updated on the current IPO dates and pricing from different companies. You can search for upcoming and future IPO dates and see which companies withdrew from the IPO process.