Youngsters celebrate Lunar New Year in Hong Kong with a dragon dance. (-RS-/flickr)
By John Major
The Japanese scatter dried beans to drive evil from the house. The
Chinese eat long-life foods. The Balinese observe a day of silence.
Thais splash water on one another. People in many parts of Asia, as
well as elsewhere in the world, love to celebrate a holiday marking the
start of a new year – a festival of putting aside the problems and
disappointments of the past, of finding new hope, of beginning anew.
But when should the new year be celebrated? There is no obvious answer
to that question. Days, months and years all flow continuously; there
is no scientific way of identifying a particular day that marks a “new
The day, the months, the seasons, and the year – the major divisions of
the calendar – are determined by the physical properties of the solar
system, especially the earth, moon, and sun. But not only is there no
“start” to these markers of time, they also do not fit together very
A day is one revolution of the Earth on its own axis: twenty-four hours.
- A lunar month is one orbit of the Moon around the Earth,
about 29 1/2 days, usually measured from new moon (unilluminated moon)
to new moon, or from full moon (fully illuminated moon) to full moon. A
lunar year (twelve lunar months) therefore is about 354 days long;
- A solar year is one orbit of the Earth around the sun, about 365 1/4 days;
- There are four seasons, each a bit more than 91 days long. The axis
of the Earth’s rotation is tilted (like a spinning top leaning to one
side), so that on any given day the hemisphere (northern or southern)
tilted toward the sun receives more light, the hemisphere tilted away
receives less. The summer solstice marks the longest day of the year,
the winter solstice marks the longest night; the spring and autumn
equinoxes occur when days and nights are of equal length worldwide. In
some cultures (e.g. the U.S.), the solstices and equinoxes are
considered to start the seasons; in other cultures (e.g. China) they
are regarded as the mid-points of the seasons. Seasons tend to be
culturally important in the higher latitudes, where the changing length
of days and nights is dramatically apparent, but not near the equator,
where days and nights are always equal.
Therefore there are three basic types of calendar:
- The solar calendar, in which solstices and equinoxes fall on
about the same date every year and a leap-day is added every four
years. Civil months are generally 30 or 31 days long and are unrelated
to lunar months. The modern Western (Common Era) calendar is a solar
- The lunar calendar, a repeating sequence of twelve lunar months. It
tracks the phases of the moon but shifts (by about eleven days a year)
annually relative to the solar year; months do not correlate with the
four seasons. The Islamic calendar is a lunar calendar.
- The soli-lunar calendar, in which extra lunar months (“leap
months”) are added from time to time (on average, about 7 extra months
per 19 years) to keep the solar and lunar years approximately
synchronized. The Chinese and Jewish calendars are soli-lunar calendars.