Conjunction or Sliver?
There is much debate about whether the new moon is based upon conjunction (no light given) and the sliver, which is when the first hint of a crescent can be spotted in the sky.

The lack of straight-forward details in scripture is how this debate came to be.
Here are a couple of reasons why Tracy and I have settled on conjunction:

Reason #1
How does a time piece work?
When a clock approaches midnight, we have exactly sixty seconds to go once we hit 11:59pm.
We can watch the sweep of the second hand as it moves around the clock face. As it approaches midnight, we can count down…
Four, three, two, one — and then the second hand is exactly on the 12 and it is midnight.  Be sure to enjoy it, because it only lasts for a moment, and then it isn’t midnight anymore…
We can start counting up the seconds of a new day.
One, two, three, four…
And so on.

Genesis 1:14-15 tells us this:
“Then Yehova said, “Let there be lights in the firmament of the heavens to divide the day from the night; and let them be for signs and seasons, and for days and years; ¹⁵ and let them be for lights in the firmament of the heavens to give light on the earth”; and it was so.”

We are told in scripture that the lights in the firmament will mark the days, and years, and they will mark the seasons. In other words, the sun, moon, and stars are a cosmic timepiece.
And we just discussed how timepieces work. Any point in time lasts only one second, and then it is no longer that point in time.

I believe the moon works the same way.
Over approximately 29.5 days, the moon goes from being full, to  giving no light, to being full again.
One whole cycle.
It is consistent, and has been so throughout recorded history.
How long does a full moon last?  If we know the light increases over time, reaching a maximum full moon, and then begins waning, we can accurately say that a full moon only lasts a moment, just as midnight only lasts for a moment.
That is the way cyclical things work.
In the same manner, a new moon lasts for but a moment. It goes from waning (reducing its light) to new moon for a moment (no light), and then it begins waxing, or gaining light.

We are told that the sliver of the waxing moon is not visible immediately, and could take as many as two or three days to become observable with the naked eye. This would put the moon well past its point of giving no light.
Do we wait until several minutes past midnight before we officially declare it is midnight?
No, we don’t. We know exactly when midnight is…  12:00am is midnight.
12:01 is not midnight.
12:02 is not midnight.
12:03 is not midnight…

So, having made a short story long, my first reason for believing conjunction is because I understand how a timepiece works, and Genesis tells us the heavenly bodies are a timepiece.

Reason #2
I believe this reason is much more compelling…
While it is difficult to see a tiny sliver around the time of a new moon, we have no such difficulty seeing when the moon is full.  A night before the full moon, the visual image of the moon is obviously not a perfect circle.  The same goes for a night after a full moon.  It is quite easy to tell, without any measuring instruments, that we are before or after a full moon.
What does this have to do with the new moon, though?

Leviticus 23:4-6
“These are the appointed feasts of Adonai, holy convocations which you are to proclaim in their appointed season. ⁵ During the first month, on the fourteenth day of the month in the evening, is Adonai’s Passover. ⁶ On the fifteenth day of the same month is the Feast of Matzot to Adonai. For seven days you are to eat matzah.

We know that half of a lunar cycle is about 14.75 days.
From the time of a new moon (no light), the First Day of Unleavened Bread is to be 15 days later.
The moon should be full for this feast.  If you establish the new moon using conjunction, the moon is ALWAYS full on the First Day of Unleavened Bread.
If you establish the new moon (and therefore the month) by sliver, the moon is always 1 to 3 nights past full.

This hint in scripture tells us that sliver is not correct.

We see the same thing a second time…
Leviticus 23:33-34
Adonai spoke to Moses saying: ³⁴ “Speak to Bnei-Yisrael, and say, On the fifteenth day of this seventh month is the Feast of Sukkot, for seven days to Adonai. 

Once again, based on scientific fact of how long the lunar cycle lasts, the beginning of Sukkot will always have a full moon, if we count our fifteen days from the time of no light.
If we go by sliver, the moon will be past full, therefore, we know we ‘missed’ the new moon.

One could argue that scripture simply says these feast days begin on the 15^th of the month, without being tied to a full moon.
One could argue that if we establish the new moon by sliver, then it makes sense that the moon is past full for the beginning of these two feasts.
I willingly admit this to be the case…

Except for this in Psalm 81:4-5
“Blow the shofar at the New Moon,
at the full moon for the day of our festival.
⁵ For it is a decree for Israel,
an ordinance of the God of Jacob.”

Yes, we are to blow a shofar at new moon.
But Psalm 81 adds “at the full moon for the day of our festival.”

This bit of scripture leads me to believe that those festival days beginning on the fifteenth of the month are on a full moon.
And if this is true, then it requires us to establish the new moon at conjunction and not at sliver.

Reason #3
The feast days are moedim.
Here is Strong’s definition for the moedim:
מוֹעֵד môwʻêd, mo-ade’; or מֹעֵד môʻêd; or (feminine) מוֹעָדָה môwʻâdâh; (2 Chronicles 8:13), from H3259; properly, an appointment, i.e. a fixed time or season; specifically, a festival; conventionally a year; by implication, an assembly (as convened for a definite purpose); technically the congregation; by extension, the place of meeting; also a signal (as appointed beforehand):—appointed (sign, time), (place of, solemn) assembly, congregation, (set, solemn) feast, (appointed, due) season, solemn(-ity), synogogue, (set) time (appointed).

We also see this in Leviticus 23:1-2
hen Adonai spoke to Moses saying: ² “Speak to Bnei-Yisrael, and tell them: These are the appointed moadim of Adonai, which you are to proclaim to be holy convocations—My moadim.

The feast days are His.
They are not ours.

If we utilize the heavenly bodies as a time piece, just as Genesis says they are, then His moedim can be calculated in advance.  We will know exactly when His appointed times are.

If we go by sliver, it may be a night, two nights, possibly even three nights before man sees the sliver.  What if the sliver should be visible to us, but there is cloud cover?  This happens sometimes. Could cover prevents the sliver from being seen until the next night, thus changing His appointed times by our inability to see.

Are we to believe that His times, His ‘appointed’ times, are to be established by man?
I do not believe this for one second.
Leviticus 23 does not say His moedim are set by man.
It says these appointed times are His.
We do not get to say when His times are.

My conclusion…
As much as I would like it to, scripture does not tell us exactly how to determine the new moon. It would be much easier if we had Step 1, Step 2, Step 3, and there you go: New Moon.

But we get no clear instructions on how to do it.
For this reason, conjunction/sliver debate will continue.
The reasons I gave above seem clear to me, but they may not seem clear to others. What is quite logical to me may be easily dismissed by others.
When scripture isn’t blatantly clear, my goal is to glean as much information from scripture as I can, and make the best logical decision I can using that information.
Based on what I shared above, I land on conjunction.

Here is the good news, though…
One day, we will be told what is correct.
I don’t know if that will happen when the two witnesses arrive.
Maybe we have to wait until Yeshua returns?
Maybe we’ll know in some other way.
No matter, I will accept truth, even if it is different from what I believe today.
In the meantime, conjunction makes the most sense to me, based on the hints we see in scripture.

What do you think?