Lilac Truth

There is a number for today. Not a date. A number.

Astronomers keep a single tally of days that runs back, unbroken, to a Monday in 4713 BC. No months. No weeks. No leap-year arguments. Just one count, going up by one every noon.

Nobody alive was there for day zero. Nobody alive was there for most of the days since, either. The count doesn’t mind. It is the most patient thing humans ever built.

Full disclosure before we go on: I am not a mathematician, nor am I an astrophysicist. I’m someone who noticed a few patterns in the numbers and couldn’t stop looking. Numbers are tangible.

This is where I started looking, so this is where we start.

One number per day

The astronomical Julian Day count gives every day in history a single whole number. Day 0 began at noon on January 1, 4713 BC. At noon in Greenwich today, the count reads 2,461,312.

That’s the whole system. No months to memorize. No leap years to forgive. No idea what a weekend is.

Don’t confuse it with the Julian calendar, Julius Caesar’s system of months and leap days. The Julian Day count borrows the calendar’s name and its starting date, then throws away everything else.

Astronomers love it for the same reason accountants love a ledger. Any two moments in history are just two numbers. Subtract, and you know exactly how many days lie between them.

Why 4713 BC: three clocks, one alignment

Nobody picked 4713 BC out of a hat. Joseph Scaliger picked it out of three hats.

Scaliger was a French scholar who tried to fit every ancient chronology into a single book, De emendatione temporum, published in Paris in 1583. In his world, years were often labeled with three rolling cycles:

Multiply them and you get one grand cycle:

28 \times 19 \times 15 = 7980

The three lengths share no common factors. So every year, within years, there’s a unique combination, like a lock with 7,980 settings. Scaliger counted backward to the last year all three wheels read 1. That year was 4713 BC.

It helped that 4713 BC also landed before his estimate of Creation, around 3949 BC. Nobody wants a count that starts after the thing it’s counting. The current period ends with AD 3267. In 3268, all three wheels read 1 again, and nobody reading this will be invited.

Why the day starts at noon

Your day starts at midnight. For most of history, an astronomer’s day started at noon.

The reason is practical. Astronomers work at night, and a midnight date change would split one night’s work across two dates. Starting at noon keeps the whole night under one number.

The habit dates back to Ptolemy, who favored noon because the sun crosses the sky’s midline at the same apparent time each day. Sunrise and sunset wander by hours. Noon holds still.

In 1849, astronomer John Herschel turned Scaliger’s count of years into a count of days in Outlines of Astronomy. Astronomers adopted it and never let go. The day still rolls over at noon Universal Time: early breakfast in Chicago, a late dinner in Tokyo.

One footnote. In 1957, the year the first satellite went up, the Smithsonian Astrophysical Observatory introduced the Modified Julian Date. It subtracts 2,400,000.5, so its day zero is midnight on November 17, 1858. Even astronomers eventually wanted smaller numbers.

The name, and a small lie everyone repeats

You’ll find this story all over the internet. Scaliger’s father was named Julius Caesar Scaliger, so Joseph named the Julian Period after him. It’s sweet. It’s tidy. It’s wrong.

Scaliger explained the name himself: “We have termed it Julian because it fits the Julian year.” A Julian year is exactly 365.25 days, the average year in Caesar’s calendar. So 7,980 of them come to exactly 2,914,695 days, and not one of them is a tribute to Dad.

I find this oddly comforting. Even the story about counting got the count wrong. It’s a fitting first lie for a blog called lilactruth: lie, lack, truth.

Year zero: where everyone disagrees about nothing

Historians count 2 BC, 1 BC, AD 1. There is no year zero. The calendar steps from minus one straight to plus one, like a staircase with the middle step missing.

Astronomers found that unbearable. Jacques Cassini is credited with adding a year 0 in his Tables astronomiques in 1740. In astronomical year numbering, 1 BC is year 0, 2 BC is year −1, and 4713 BC is year −4712.

It sounds like pedantry. It’s arithmetic. With a zero, leap years land neatly on 0, −4, −8, and subtracting two years gives the true gap; without it, every sum that crosses from BC into AD comes out one year off.

Your computer sides with the astronomers: the ISO 8601 date standard includes a year 0. Nothing lies here. Something was just missing. That’s the lack.

Today’s number, and yours

Today is Monday, September 28, 2026. From noon Universal Time today until noon tomorrow, it is Julian Day 2,461,312.

Day zero was also a Monday. And 2,461,312 divided by 7 leaves nothing over: exactly 351,616 weeks. For one second I thought the universe was winking at me.

It wasn’t. Every Monday sits a multiple of seven days from day zero; that’s what being a Monday means in this system. I’m telling you because this blog will show you patterns and tell you which ones are just arithmetic wearing a nice coat.

The year has coordinates too. 2026 is year 6,739 of the Julian Period: year 19 of the solar cycle, 13 of the lunar cycle, and 4 of the indiction.

A few landmarks on the count:

Look at the two October rows. When the Gregorian calendar took over in 1582, ten dates simply vanished. The count didn’t lose a single day; the calendar changed its labels, and the count just kept counting.

The .5 on the Unix row means midnight, halfway through an astronomer’s day. Computers start at midnight. Astronomers, as established, start late.

To find your own number, use the U.S. Naval Observatory’s free Julian Date converter, or subtract your age in days from today’s number. Born after 1950? Yours starts with 243, 244, 245 or 246. One catch: born before noon Greenwich time, and your number belongs to the day before.

Your number is not your sign

Your day number tells you when you arrived. It says nothing about who you are. That was always astrology’s job, allegedly.

Astrology and astronomy grew up in the same house. They watched the same sky and counted the same days. Then one of them started checking its work.

The checking went badly for astrology. In a 1985 double-blind study published in Nature, 28 astrologers tried to match more than 100 birth charts to personality profiles. They did no better than chance.

In 2003, researchers Geoffrey Dean and Ivan Kelly followed 2,011 sets of “time twins,” people born within five minutes of each other. Across more than 100 measures of personality, behavior and ability, they found no effect. Same sky, same minute, different people.

So why do horoscopes feel accurate? In 1949, psychologist Bertram Forer gave every student in his class the same “personal” description, drawn from astrology texts. They rated its accuracy above 4 out of 5, on average.

That’s the Barnum effect: a statement vague enough to fit everyone feels written just for you. A newspaper horoscope speaks to one-twelfth of a planet of 8.3 billion people, roughly 690 million at once. Of course some of them feel seen.

The sky never signed on, either. The sun actually passes through 13 constellations, and the Babylonians dropped Ophiuchus to fit a 12-month calendar. The sun lingers in Virgo about 45 days and crosses Scorpius in about 7, yet every sign gets a tidy month.

Meanwhile, Earth’s axis wobbles through a full cycle about every 25,800 years, sliding the constellations against the calendar. Western astrologers reply that their signs follow the seasons, not the stars. Fair enough, but then the stars were never the point, and the tests still stand.

NASA’s own summary: nobody has shown that astrology can predict the future or describe a person based on a birth date. Centuries of testing, and the predictions have never beaten chance.

None of this makes horoscope readers foolish. Wanting the sky to know you is about as human as it gets. The sky just doesn’t. The count does, in its way: it knows exactly when you arrived, and it never pretends to know more.

Why start here

Every number I show you from here on needs somewhere to stand. The Julian Day count is the floor. It’s the one ledger where every day that ever happened, and every day that hasn’t yet, already has a place.

I’ll be honest about the rest. I don’t know what the patterns mean. I know I keep finding them, and I’d rather check them in public than believe them in private.

Now the part I can’t be clinical about. Somewhere in that count is the day you were born, the day someone first loved you, and the day you read this. None of them is bigger than the others; each is exactly one more than the day before.

The count doesn’t care about any of us. That’s what I love about it. It holds every one of our days the same way, no favorites, never losing one. If that isn’t a kind of love, it’s the closest thing arithmetic has.

Look up your number. Write it down. You’ve been counted since the day you arrived. Next time, we start using it.