AS THE vice Provost of Trinity and I went home on the DART the other night, he remarked how bright the planet Venus was of late. He's right, of course: indeed I am sure vice provosts always are, by definition. But on this particular night the shining planet and the bright crescent of the waxing moon were close, the latter turned away from Venus as if miffed, and the two together - the moon and Venus - provided quite a spectacle. One could almost believe that Coleridge's astronomical impossibility might come to pass:
There clomb above the east ern bar.
The horned moon with one bright star
Within the nether tip.
The clear sky augured well for the coming weeks. It was believed, in days gone by, that each lunar month took its meteorological character from the weather on the fourth and fifth days after the new moon. The popular rhyme described it thus:
The first and second never mind,
The third regard not much;
But as the fourth and fifth you find,
The rest will be as such.
Another common feeling was that the orientation of the young crescent moon had an influence upon the weather. A crescent moon on its back - described as "holding water"
foretold strong south westerly gales and heavy rain, while an upright or "standing" crescent moon brought on the cold. Nowadays, of course, we know that the attitude of the young moon depends solely on its situation relative to the sun; it varies with the time of year, but not with the weather.
The 18th century astronomer, Sir William Herschel, who should have known better, went even further. After years of careful study, he concluded that the character of the weather for the following seven days depended on the exact time each of the four phases of the moon began - the New Moon, the First Quarter, the Full Moon and the Last Quarter.
In wintertime, for example, if the phase in question began between noon and 2 p.m., snow and rain would be frequent in the coming week; a change of phase occurring between 2 and 4 p.m., on the other hand, indicated fair and mild weather. In this way, Herschel carefully tabulated the significance of a lunar phase change in each of the 12 two hourly intervals of the day, and provided a similar tabulation for the summer months. Present day wisdom, however, is summed up in the rhyme:
The moon and the weather may change together,
But a change in the moon does not change the weather.