MONTH, in astronomy, properly the time in which the moon makes one com plete revolution round the earth, or ap pears to return to precisely the same point in the heavens from which it started. This may be from change to change, from full moon to full moon, or in an indefinite number of other ways. The time of the revolution now de scribed is properly 29 days. 12 hours, 44 minutes, and 3 seconds. Twelve periods, called lunar months, fall short of a year by about 11 days. Lunar months were used by the ancient Jews, as they still are by their modern successors and by the Mohammedans. Also a solar month; the period for the passage of the sun through one of the signs of the zodiac. Twelve of these periods constitute a year.
In law, formerly the word month in a statute meant a lunar month, but it was made to signify calendar months unless otherwise expressly designated. Anom
alistic month, the time taken by the moon in passing from one perigee to the next, viz., 27 days, 13 hours, 18 minutes, and 37.4 seconds. Nodical month. the time taken by the moon in revolving from one node to the same node again, viz., 27 days, 5 hours, 5 minutes, and 36 seconds. Sacred month: suggested at Chartist Convention, London, 1838, during which the working classes were to ab stain from labor to compel the govern ment to concede the Charter.
Sidereal month, the time taken by the moon in passing from one star to the same star again, viz., 27 days, 7 hours, 43 minutes, 11.5 seconds. Tropical or periodic month, the time taken by the moon in passing from any point of the ecliptic to the same point again, viz., 27 days, 7 hours, 43 minutes, 4.7 seconds.