Jeffery Schneider, age 11, of Milwaukee, Wisconsin, for his question:

Is it true that the year has 365 1/4 days?

For three years in a row, our calendar has 365 days. Then it has a leap year with 366 days. This should give us a hint that there is something rather odd about the number of days in a year. Actually there are many ways to measure the year, but the one that concerns us most is the number of days in the calendar. This is based on the Tropical Year, the period of time it takes our orbiting earth to travel around from one spring equinox to the next. Its actual length is 365 days, five hours, 48 minutes and 45 seconds. This is about 12 1/2 minutes shorter than 365 1/4 days.

The calendar year starts after midnight of December 31st and we need an even number of days to complete it. The orbiting earth, however, does not fit a neat number of whole days into each year. So we make allowances. Our calendar saves up the quarter days until there are four of them. For three years we count off 365 days, then use the four quarter days to add an extra day to a leap year with 366 days.