The Question was raised regarding what factors are needed to sight a new moon. Here is the promised answer. First, I think folks would like the answer to be simple, like "you can sight the New Moon when it is 3% and the elongation is 10 degrees"... But the answer isn't that simple. In fact, some have sighted a New Moon when it is only 1%, but the conditions have to be absolutely - and unusually - perfect... So much so that this almost never happens. So, a simple formula doesn't work for 100% accuracy in determining when New Moon crescents will be visible... Sorry...
Perhaps the most important factor for reliably sighting the new moons and getting the dates right is practice in actually sighting the new moons. We have found great insights and help from just practicing sighting it. You get a flavor for it, so to speak. And your ability to calculate the new moon dates improves the more experience you get in this.
Having said that, the next most important factors for determining the new moon sighting are phase, altitude and elongation. Of these, elongation is the most important. Also, you can use the date of the conjunction (dark phase of the moon) to help you find the new moon date... The new moon sighting should be at least 24 hours from the actual conjunction.
The size and brightness of the lunar crescent depends on the elongation of the Moon from the Sun, which is the apparent angular distance between their centers. Elongation has been called the arc of light. If we know the value of the elongation at any instant, we can immediately compute the width of the crescent.
Elongation is more accurate than moon's percentage of illumination in determining whether it is visible or not. And, honestly, this is where accurately pre-calculating new moon dates gets a bit complicated...
So, for all who are feeling a bit overwhelmed and intimated at this point, please know that Lighted Way Ministries plans to provide this information for calendation.
What is the value of the elongation when the Moon's age is 1 day? (1 Day after the lunar conjunction). It varies, depending on several factors:
1) The elongation at the lunar conjunction (wrongly now called the "New Moon" day). The moon can pass directly in front of the sun at the lunar conjunction (which it does when a solar eclipse will occur) or the lunar conjunction can pass as far as five degrees from the sun.
2) The speed of the Moon in its orbit. The moon's orbit is elliptical, and its speed is greatest when it is near perigee (when the moon is nearest to earth). If perigee occurs near the lunar conjunction (dark phase of the moon), the moon will appear to be moving away from the sun at a greater than average rate (making elongation possibly happen sooner).
3. The distance of the Moon. Again, because of its elliptical orbit, the distance of the moon varies, so even if the moon moved with a constant speed, its angular motion as viewed from the Earth would be greater when the moon is near perigee.
Note: some of the earliest reliable sightings of the crescent occur near elongations of around 10 degrees.
Simply specifying the age of the Moon cannot tell the whole story. The elongation of the Moon doesn't tell the full story either. But, of the two parameters, the elongation is much more reliable parameter to use as a starting point in assessing the lunar crescent visibility at any given date and time.
For more information about what it takes to make a new moon crescent visible, visit the US Naval Observatory at: https://aa.usno.navy.mil/faq/crescent
Here is a link to a moon calculator... Please note, for challenging moon dates (when conditions are such that visibility is in question) it is best to use 2-3 different calculation sources to verify sightability:
Once again, this information is provided in answer to a question raised in class today. This information is not intended to overwhelm anyone. As students of the Torah, we all need to know how a Biblical calendar should be made. We have studied this. But, it is not wrong to rely on someone else, longer in the priesthood role, to give the timing of the moon sightings. After all, the Children of Israel left determining the moon-sightings and dates of new moons to the priests.
So, please don't feel overwhelmed. If you know how to calculate the Feast Days, as shown in class, that is sufficient to be protected from calendar doctrinal confusion.
COURSE FEE FOR JANUARY:
Quick reminder... The course fee for this class, for January is now due. Please send online through the Lighted Way Ministries' Donation center. For convenience, you may use the following button. If you have already sent the $100.00 for December, please disregard this reminder and thank you so much!
ANNOUNCEMENTS:
The following is our class schedule for January, 2024:
Mon & Wed, January 15 & 17 - Torah Class will meet, as scheduled, live on Zoom, on both these days.
Mon & Wed, January 22 & 24 - Torah Class will meet, as scheduled, live on Zoom, on both these days.
Mon & Wed, January 29 & 31 - Torah Class will meet, as scheduled, live on Zoom, on both these days.