Thursday, September 15, 2016

Muggeridge's Law

From Tom Wolfe's "Stalking the Billion-Footed Beast:  A literary manifesto for the new social novel," Harpers, November, 1989. 
While Malcolm Muggeridge was the editor of Punch, it was announced that Khrushchev and Bulganin were coming to England. Muggeridge hit upon the idea of a mock itinerary, a lineup of the most ludicrous places the two paunchy pear-shaped little Soviet leaders could possibly be paraded through during the solemn process of a state visit. Shortly before press time, half the feature had to be scrapped. It coincided exactly with the official itinerary, just released, prompting Muggeridge to observe: We live in an age in which it is no longer possible to be funny. There is nothing you can imagine, no matter how ludicrous, that will not promptly be enacted before your very eyes, probably by someone well known.

Friday, September 09, 2016

A full Moon can occur on Easter Sunday.

The rule for finding the date of Easter is usually stated as follows:
  1. Determine the date of first full Moon on or after the first day of Spring.
  2. Easter is the Sunday after that.
This eliminates the possibility of the Moon being full on Easter Sunday.

Except that it doesn't. A lunar eclipse can occur only when the Moon is full, and there was a partial lunar eclipse on Easter Sunday, April 12, 1903.

There are two factors in the rule for Easter that contribute to this situation.
  1. The first day of Spring is always assumed to be March 21. This is not exactly true. The vernal equinox (determined astronomically) can occur on March 19, 20 or 21.
  2. The full Moon used is not the astronomical full Moon, but an ecclesiastical full Moon, i.e., one that is used for ease of determination.
The second factor is what caused Easter Sunday in 1903 to fall on the same date as the astronomical full Moon.

The date of Easter is actually determined by the Roman Catholic Church using tables that were set up when the Gregorian Calendar was established in 1582.

For further information: http://aa.usno.navy.mil/faq/docs/easter.php