Calendar mysteries

Were you born on this rare date? Only 1 in 1,461 people were

Most of us think we know the calendar pretty well, and if we don’t, our phones are there to remind us of dates and events. But the way humans measure the passage of time hasn’t always been the same. From the origins of month names to the truth behind leap years, today we’re going to share 10 surprising facts you probably didn’t know about the calendar.

The probability of being born on February 29 is 1 in 1,461. Although birthdays on this date are rare, people born on it even have a name: leaplings. Leaplings officially get to celebrate their birthday on February 29 only once every four years, but what happens in the other years? While some people prefer not to jump to another month, March 1st is considered more astronomically accurate, as it comes directly after February 28.

The Earth’s orbit is elliptical, which means there are times when we are closer to the Sun and other times when we are farther away. In January, Earth is at its closest point to the Sun, known as "perihelion." You might wonder how we can be closer to the Sun during winter, but the seasons are caused by Earth’s tilt, not by our distance from the Sun. On the other hand, the month when we are farthest from the Sun is July, and this point in the orbit is called "aphelion."

Due to its particularly short duration, February is the only month that can lack a full moon. Lunar cycles are 29.5 days long, which means that, approximately every 19 years, February has all the lunar phases except the full moon. When this happens, both January and March have two full moons, with the second one being called a "Blue Moon"; and that's why, when we say "once in a blue moon," we're talking about something that happens very rarely. The next time this will happen will be in the year 2037.

Did you know that our calendar has a name? That’s right; most of the world uses the Gregorian calendar, named after Pope Gregory XIII, who introduced it in 1582 as a reform of the older system.

The main difference lies in how leap years are handled. The previous system, known as the Julian calendar, added a leap year every four years, assuming a year lasted exactly 365.25 days. However, a real solar year is slightly shorter. To fix this, the Gregorian calendar keeps leap years every four years with one exception: century years (like 1900) are not leap years unless they are divisible by 400 (such as 2000).

But before the Julian calendar, ancient Rome used an even older system with one key difference: it had only 10 months. This calendar began in March and ended in December, totaling just 304 days. What about the remaining days? They were considered a winter gap and simply weren’t counted. Around 700 BC, January and February were added to fill that gap, and these changes were later standardized under Julius Caesar’s reform in 45 BC, when he introduced the Julian calendar.

The names also come directly from life in ancient Rome, where months were named in honor of deities and important festivities. For example, March was named Martius after Mars, the god of war, because it marked the start of the military campaigning season. Aprilis, the Roman name for April, comes from the Latin verb aperire, meaning "to open," in reference to the arrival of spring. May was named Maius after Maia, the goddess of fertility and growth, and June was named Iunius in honor of Juno, the Roman goddess of marriage.

What about the rest of the months? From July through December, they were originally named after their position in the year. Since March was considered the first month, July was called Quintilis ("the fifth"), August was Sextilis ("the sixth"), September comes from septem, meaning "seven" in Latin, October from octo ("eight"), November from novem ("nine"), and December from decem ("ten").

Most of these names remained similar, with two exceptions: Quintilis was renamed Iulius to honor Julius Caesar after his death, and Sextilis became Augustus, in honor of Augustus Caesar, the first Roman emperor.

The days of the week are no exception to Roman tradition. Sunday was named dies Solis ("day of the Sun"), Monday was dies Lunae ("day of the Moon"), Tuesday was called dies Martis (day of Mars), Wednesday dies Mercurii (day of Mercury), Thursday dies Iovis (day of Jupiter), Friday dies Veneris (day of Venus), and finally, Saturday was dies Saturni (day of Saturn).

As you may have noticed, only Saturday retained its Roman root, while Sunday and Monday kept their meaning but were translated. What happened to the rest? They were influenced by Norse mythology, resulting in Tuesday being named for Tyr, a Norse god of war; Wednesday after Woden (Odin), the Norse interpretation of Mercury; Thursday from Thor, the god of thunder, replacing Jupiter; and Friday from Freya, a Norse goddess linked to the Roman Venus.

In the United States, Sunday is considered the start of the week. This tradition has religious and cultural roots, and it’s shared by many parts of the world, but not all of them. In fact, several other English-speaking countries do it differently: places like England, Australia, and parts of Canada consider Monday the first day of the week, with Sunday closing it out.

The 12 longest-living animals on Earth (and how they cheat time)

Nature doesn’t just create beauty, it crafts survival miracles. While most animals have short lives, a rare few have mastered the art of staying alive for centuries, even millennia. These aren’t just long-lived creatures; they’re nature’s ultimate time travelers. From the frozen depths of the oceans to the darkest corners underground, they’ve developed bizarre, brilliant strategies to cheat death. Get ready to meet 12 animals whose lifespans will absolutely blow your mind.

Record age: up to 15,000 years

This unassuming sea sponge thrives in the freezing waters of Antarctica, where temperatures hover around 28.6 °F—so cold that biological processes hit the brakes. In such icy conditions, metabolism slows to a crawl, allowing these sponges to live for thousands of years.

Some have reached impressive sizes of over 3 feet tall and have been around since mammoths were still thundering across the tundra. They don’t move, they don’t stress, and they barely change, just quietly existing while centuries pass them by. Their secret to extreme longevity? Glacial patience, deep-sea stillness, and a lifestyle that redefines "low-maintenance".

Age: technically… infinite

This tiny jellyfish, no bigger than a fingernail—less than 0.2 inches—is like the ocean’s very own Benjamin Button. What makes it truly extraordinary is its ability to rewind its life story, flipping back to a youthful, juvenile stage whenever it wants. While it’s not completely invincible (predators and other threats are still very real), if left undisturbed, it can keep hitting the reset button on aging indefinitely, making it one of the most fascinating "time-benders" in nature.

Record age: 507 years

In 2006, a special clam was discovered buried deep in the seabeds of the North Atlantic. Scientists were able to determine that it had been there since at least 1499—that’s centuries before the United States was even a thought! This ancient marvel, nicknamed "Ming", was able to perfect a slow-and-steady approach to life. Growing at a snail’s pace and barely budging, Ming’s sedentary lifestyle turned out to be a brilliant strategy for beating the clock. Who knew doing almost nothing could be the ultimate secret to longevity?

Record age: estimated 392 years

These sharks aren’t your average ocean cruisers—they can stretch over 20 feet long and weigh up to 2,200 pounds. But what’s really mindblowing is how slowly they move, like they’re in a permanent state of deep relaxation. Living in the icy Arctic waters, these giants don’t hit adulthood until they’re about 150 years old, and some can glide through the depths for nearly 400 years. Imagine that! These ancient swimmers were already around before America declared independence... and they are still out there, silently roaming the seas!

Record age: over 211 years

This whale is a true ocean giant, stretching up to 60 feet long and weighing a staggering 200,000 pounds. But what makes it stand out isn’t just its size but its age. Some of these majestic creatures carry harpoons from the 1800s still lodged in their skin, like walking history books. Just picture living so long that you’re literally carrying outdated technology embedded in your body—talk about being a time traveler of the seas!

Record age: 200 years

Spanning the chilly Pacific coastline from California all the way up to Alaska, this spiky little ball—about 7 inches across—is full of surprises. It munches on algae and calls the deep, dark ocean its home, thriving at depths of up to 300 feet. Don’t let its size fool you: this prickly creature is a true elder of the cold seas, quietly outliving many ocean neighbors while keeping a low profile. A tough, slow-living veteran wrapped in spikes!

Record age: 226 years

Meet Hanako, a legendary Japanese koi who swam through life for an astonishing 226 years. Scientists discovered how old she was by studying the rings on her scales, much like counting the growth rings of a tree. These colorful, ornamental fish aren’t just symbols of good fortune; they’re also secret long-lifers with the potential to celebrate over two centuries of birthdays, as long as they get the right care and a peaceful pond to call home.

Record age: 190 years

Jonathan is a male tortoise living on the remote island of Saint Helena in the South Atlantic Ocean. He was born back in 1832, and he’s still happily chomping lettuce and soaking up the sun today. Weighing in at more than 400 pounds and measuring around 3 feet long, Jonathan holds the title of the oldest known living land animal on the planet. If he could share tales, they’d span nearly two centuries of history. Imagine that!

Record age: 152 years

This ancient-looking fish, with its whisker-like barbels, looking like a tiny underwater submarine, prowls the lakes of North America. It can reach an impressive length of up to 7 feet and weigh around 200 pounds. These slow-living creatures don’t rush into adulthood—they start breeding only around age 20—and then take their time cruising through life at a leisurely pace. Believe it or not, one legendary catch in Wisconsin was estimated to be over 150 years old!

Record age: over 90 years

This chunky, night-loving parrot from New Zealand is a true oddball—it can’t fly, snores like a grumpy grandpa, and smells like fresh flowers. Despite its quirks, this bird boasts an impressively long lifespan. Sadly, it teeters on the edge of extinction. The oldest known kakapo, affectionately named Richard Henry, lived 90 years, earning him the title of the charmingly eccentric elder statesman of the avian world.

Record age: 37 years

This tiny, kooky rodent—barely 3 inches long and just over an ounce in weight—could’ve been cast straight from a sci-fi apocalypse flick. Dwelling in vast underground colonies across Africa, it’s practically invincible to cancer, pain, and the usual effects of aging. Scientists are fascinated by this little marvel, even if it’s not winning beauty contests anytime soon. Its superpowers make it a star in longevity research!

Record age: estimated 100+ years

Lobsters have a totally different rulebook than us when it comes to aging. They don’t really grow old; they just keep getting bigger and bigger. Some giant lobsters weigh over 40 pounds and stretch beyond 3 feet long. Their biggest threats? Not old age, but predators or the risky process of shedding their shells. In theory, they could live forever if left alone—but let’s be honest, not many get to enjoy a peaceful, lobster-sized retirement!