Calculating the Conjunction
The conjunction
happens at the same moment in time no matter where a person is on the
earth. According to Josephus,
Seth’s sons were the first astronomers and had developed a knowledge of
the precise cycles of the sun, moon and stars (what we today call
astronomy). We can likewise determine the various cycles of the moon
with precision.
1. Toward the end of the week before the
conjunction, shortly before sunrise sight the waning moon above and towards the eastern sky.
2.
With your hand measure the angle between the waning moon and the
horizon, just as the sun rises; watching for a time that most closely
fits measuring degrees with your hands.
3.
Mark down the date, the degree of the angle (eg.25°) and the time
(eg.4:30 a.m.)
The angle in this
example is 25° between the moon and the horizon where the sun is just
appearing; and this is about 2 days before the conjunction (or what you
believe will be the day of the conjunction). Let's use 4:30 a.m. when
the sun appears. The moon travels
around the earth once a month in about 29.53 days, on average (1
revolution is 360°). We do a calculation: 29.53 days X 24 hours a day =
708.72 hours (on the average) in one 360° revolution of the moon in one
month. Then divide 360° by 708.72 hours to determine that the moon moves
precisely .508° or about .51° in
one hour. The moon moves relative to the sun by an amount .51°; multiplying
by 24 hours, makes the movement of the moon about 12.2°
every day.
The formula is the
angle of the sun to the moon at sunrise divided by the rate of change
per hour, which equals the time of conjunction, in hours, from the time
you took your measurements. That's all you need to know.
The moon will travel 360° from new moon to
new moon in 29.53 days, on average. Take the 25° measurement for the
angle between the sun and the moon at sunrise and divide it by the .51°
rate of change per hour. This gives us the amount of time it will take
for the sun and moon to reach the point of alignment or
conjunction.Therefore 25° divided by .51 degrees per hour gives us 49.2
hours. It will take 49.2 hours from 4:30 a.m., when we determined our
angle between the sun and the moon, for the moon to travel the 25° still
needed to reach conjunction. So, how many days away is 49.2 hours from
the time we determined our angle between the sun and the moon? How many
days away is the conjunction? Divide 49.2 hours by 24 hours (don't use
fractions of a day for the remainder; we want whole days with the
remainder in hours) and we come up with 2 days, with 1.2 hours or 72
minutes remaining. Add this 2 days to the date marked down, and we
arrive at 4:30 a.m (2 days later). Add the remaining 1 hour and 12
minutes to 4:30 a.m., and that brings us to 5:42 a.m. as our “rough”
calculation for the time of the conjunction. The new month then begins
after sunset the following evening in this example.
