bhagolblog

Elsewhere · The gist

Ekadashi across the date line

The same monthly fast falls on a Thursday in Auckland and a Wednesday in California, and the two sunrises that decide those dates are only three hours apart, so the date on the calendar tells a family close to the opposite of how far apart they really are.

The essay7 minThe gist1 min

This is the short way in. The essay has the working, the sources and the sky.

In October 2026 the two households are one day apart on paper and three hours apart in fact. One month earlier they share a date, and are nearly 20 hours apart.

Indian fasts and festivals are fixed to the moon, not to a date. The measurement is called a tithi, a lunar day. It is one step in the widening gap between the moon and the sun, and it runs a little shorter than one of our days, so it will not sit neatly inside a date. The printed almanac, the panchang, settles which date carries a tithi's name by one test: whichever tithi is running when the sun comes up in your own town gives that whole day its name. Ekadashi is the eleventh of these lunar days, and a great many households fast on it.

The test uses your sunrise. That is where two households drift apart.

Take Auckland and Fremont, California, in October 2026. The eleventh lunar day begins and ends at two instants that are the same for the whole planet. Auckland's sun comes up inside it on Thursday 22 October. Fremont's sun comes up inside it on Wednesday the 21st. Both sheets are right, and both households are following the same rule.

Almost everybody blames the international date line. It is not the cause. Auckland's Thursday sunrise and Fremont's Wednesday sunrise are 3 hours and 6 minutes apart in real time. The two households are nearly in the same morning. It is only the calendar that restarts in the ocean between them.

Go back one month and it reverses. In September 2026 both cities keep the fast on Tuesday 22 September, and those two sunrises are 19 hours and 45 minutes apart. Same date, nearly a whole day apart.

So the date is the least useful thing said on the phone call. Two people who both say "today" may be almost a day apart. Two who say "today" and "tomorrow" may be three hours apart. The reliable thing to exchange is an hour with a city attached to it.

Words decoded

tithi (तिथि)
a lunar day, one step in the widening gap between the moon and the sun; a little under 24 hours long, so it slips out of step with our dates
ekadashi (एकादशी)
the eleventh of those lunar days, counted from the new moon and counted again from the full moon, so it comes round twice a month; a common fasting day
panchang (पञ्चाङ्ग)
the printed Indian almanac that lists each day's lunar measurements, computed for one named city
parana (पारण)
the meal that ends the fast the next morning, taken inside a window printed on the sheet
international date line
the line through the Pacific where the calendar date changes; an arrangement between governments, with nothing in the sky underneath it
Why anyone should careA family split across the Pacific usually assumes that a one-day difference means somebody's app is set wrong. It normally means nothing of the kind, and worse, the date hides how close together the two households actually are. Knowing that turns an argument about who is correct into a simple exchange of two sunrise times.
Read it properly, 7 min Ekadashi across the date line