"I have to wait a month longer this year to eat apples and honey," complains Jeremy, 16.
"No, the first of Tishrei is always the first of Tishrei," I say, referring to the date on the Jewish calendar that marks our New Year.
"But it's not till Oct. 4," he answers.
Jewish time, to most people, means that Shabbat services and synagogue board meetings begin 15 to 30 minutes late. But true Jewish time means that our days and our holidays adhere to a primarily lunar calendar, corresponding to the waxing, waning and reappearance of the moon as it circles the earth. Jewish time also means that our days begin at sunset and our months begin when the crescent of the new moon is just visible. (It's no mistake that the Hebrew word for month, chodesh, is related to the Hebrew word for new, chadash.)
And it means that our days don't correspond -- except every 19 years, give a day on either side -- to the dates on our secular or Gregorian calendar, based on the earth's orbit around the sun.
"Wait till 2043," I say. "Rosh Hashanah will fall on Oct. 5, the latest it's ever been."
But the first of Tishrei will always be the first of Tishrei, whether it falls on Sept. 5 or Oct. 5. And around the world, all on the same day, we Jews will be carrying out God's commandment, expressed in Leviticus 23:24, "In the seventh month, on the first day of the month, you shall observe complete rest, a sacred occasion commemorated with loud blasts."
Devising this Jewish calendar, and celebrating sacred occasions at their appointed times, as God instructs in Leviticus, entails more than running outside at sunset and staring at the sky looking for the first appearance of stars.
"Which, in Los Angeles, you can't even see," my frustrated amateur astronomer husband, Larry, says.
Although that's exactly what used to happen. In ancient times, when people saw the new moon, they would report their sighting to the Sanhedrin, the high court in Jerusalem. After the Sanhedrin confirmed their testimony, the religious court would declare a new month and alert the Jewish community -- initially by lighting fires atop mountaintops and later by dispatching messengers.
But there were some complications. For starters, the mean lunar month is 29 days, 12 hours, 44 minutes and 3 1/2 seconds, making a lunar year 354 days. That's about 11 days shorter than the solar calendar, which runs 365 1/4 days. And that's problematic for the pilgrimage festivals -- Pesach, Shavuot and Sukkot -- which are agricultural holidays and thus season-sensitive.
After all, you couldn't very well celebrate Pesach, known as Chag Ha-Aviv (the Festival of Spring), in October.
"And you couldn't celebrate Chanukah in August, right before school starts, because we'd get pencils and binders as gifts," Jeremy notes. "How messed up would that be?"
So the ancient Jews had to intercalate their lunar year to correspond with the solar year.
"Intercalate? Is that even a word?" asks Gabe, 18.
"Ask Hillel the Second," I answer.
Hillel the Second was a patriarch who, as head of the Sanhedrin, devised a fixed Jewish calendar based on mathematical and astronomical calculations that standardized the length of months to 29 or 30 days. He also cleverly inserted an extra month -- seven times every 19 years, in the third, sixth, eighth, 11th, 14th, 17th and 19th years of the cycle -- to keep the holidays regulated according to seasons.
Maybe he was heeding the psalmist who said, in 90:12, "Teach us to count our days rightly, that we may obtain a wise heart." Or maybe he forgot his wife's birthday one too many times.
A more informal form of intercalation probably appeared earlier, scholars surmise. For example, if the road to Jerusalem was too muddy to travel or if there were not enough baby lambs to sacrifice, the ancients waited another lunar cycle to celebrate Pesach. This leap month is Adar II, though technically Adar I is the extra month. And the month of Nisan, which contains the pivotal holiday of Pesach, remains the start of the calendar year.
"What Hillel and the other Jews didn't do is make sure that all the Jewish holidays fall on the weekdays," points out Danny, 14, always happy to miss a day of school.
But the ancient Jews did succeed in giving us, with their lunar/solar calendar, a way, despite our living in mostly urban and technological environments, to stay tuned to the natural rhythms of the universe.
And they did succeed in giving us, despite our living in a primarily secular world, a way to stay tuned to the natural rhythms of the Jewish universe, moving us forward through the cycles of the Jewish year, which provide a range of emotional and spiritual experiences while rooting us solidly in our traditions and history.
And so, at sunset on Oct. 3, we celebrate Rosh Hashanah. We celebrate a new moon, a new month and the new year of 5766. And as we reflect on the past year and commit to changes in the coming year, we know, as always, that Rosh Hashanah is right on time.
Freelance writer Jane Ulman lives in Encino with her husband and has four sons.