Rosh Hashanah 20b — the Talmud in English

And we answer:

this one,

when the new moon is seen on the thirtieth day, and the witnesses do not testify concerning it, this is

seen as falsehood.

The falsehood is apparent to the public, because there are many others who saw the moon, and it appears that the court intercalated the month through falsehood.

But

this one,

when the new moon was not seen at its proper time, even if the witnesses falsely testify that they saw it, nevertheless

it is not seen as falsehood.

This falsehood is not apparent to the public, for although the other people did not see that the moon had renewed, it is possible that the witnesses saw it.

And the Gemara continues to discuss the matter of sanctifying the new moon:

Samuel said: I can establish the calendar for the entire diaspora,

I can establish the order of the years and the months for all the people of the diaspora without seeing the moon, because I am expert in the course of the moon and in the order of the constellations. And if I had to establish a calendar, I would be capable of doing so.

Abba, the father of Rabbi Simlai, said to Samuel:

Does

the Master know this matter that was taught in the secret of intercalation,

does the Master know what is the explanation of the words of the beraita called “the secret of intercalation,” in which matters were stated by way of allusion?

“If it was born before midday or if it was born after midday”.

There is a distinction between whether the birth of the moon was before midday or after midday. And this matter is an allusion.

He said to him,

Samuel:

No,

I do not know its meaning.

Abba, the father of Rabbi Simlai, said to him:

the father of Rabbi Simlai,

Since the Master does not know this, there is another matter that the Master does not know.

From the fact that you do not know this concept, it appears that there are additional matters that you do not know.

When Rabbi Zeira went up,

when Rabbi Zeira went up to the Land of Israel,

he sent them,

to his colleagues in Babylonia, two matters that he had learned in the Land of Israel: first, concerning those who hold that the witnesses who did not see the renewal of the moon on the thirtieth day are threatened that they should give false testimony in order to sanctify the month before its proper time. This does not apply in every case. Rather—

There must be a night and a day from the new month.

It is necessary that at night, the eve of the thirtieth day, the moon belonging to the preceding month should no longer be seen.

But if at night, the eve of the thirtieth day, the moon from the preceding month can still be seen, the entire day follows the night preceding it.

And since the night belonged to the preceding month, the day also necessarily belongs to the preceding month.

And the new month is not sanctified before its proper time, because since the moon of the preceding month was still visible at night, everyone knows that this day is not Rosh Chodesh. And if they were to sanctify the month on it before its proper time, the matter would be plainly seen by everyone as falsehood.

2.

And this is what Abba, the father of Rabbi Simlai, said

before Samuel, and since he did not know how to explain the distinction between “born before midday” and “born after midday,” its explanation is as follows:

The birth is the time when the moon is renewed and begins the cycle of the new month.

The moon circles the earth [according to the average calculation known from earlier generations, through the tradition of the Sages] once in twenty-nine days, twelve hours, and 793 parts [each “part” is approximately three seconds].

Only half of the moon is illuminated by the rays of the sun, whereas its other half is perpetually dark.

During its orbit around the earth, the illuminated portion of the moon that faces the earth changes gradually. At the beginning of the orbit, mainly the dark portion of the moon is turned toward us, and only a tiny portion of its illuminated half is turned toward us. The gradual filling of the moon, from the beginning of the month until its middle, and likewise the waning of the moon after the middle of the month, is the result of the constant change in the position of the moon as it orbits the earth.

The sun shines its light upon the moon, and the moon reflects it toward the earth. When the moon completes half of its orbit around the earth, the entire side of the moon that faces the rays of the sun is exposed toward the earth, and therefore in the middle of the month the moon is seen shining in its entirety. At the moment of the birth itself, the moon’s monthly orbit around the earth is completed, and then the moon is not visible at all. For at that time it is located between the earth and the sun, and the entire illuminated side faces the sun.

Toward the end of the orbit, and likewise at the beginning of the orbit, the moon “disappears” from the sight of every observer, because of the small number of rays of light reflected from it, since the human eye is then unable to receive such a small amount of light.

They calculate its offspring,

the time of the birth of the moon of the month of Tishrei, which is Rosh Hashanah, according to calculation, and accordingly they know when it will be visible:

If

it was born before midday

that day—

it is known that it will be seen

by the eye after six hours,

close to sunset,

and that day is Rosh Hashanah.

And if

it was not born before midday—

it is known that it will not be seen

by the eye

close to sunset, but only afterward, and it is impossible to make it Rosh Hashanah.

For the moon is seen after the birth at the southwestern corner of the sky.

And it is close to the people of the Land of Israel who dwell in the west, as follows. And therefore they see it six hours after the birth.

and it is close to the inhabitants of Eretz Yisrael, who live in the west, as will be explained below. Therefore, they see it six hours after the molad.

And we inquire about it:

What practical difference is there

when the moon will be visible? For the month is sanctified on the basis of witnesses, and in any event they cannot testify until the moon is visible!

He said,

he answered,

Rav Ashi:

There is a practical difference

for disproving

the witnesses!

If we know that the birth was after midday, and the witnesses testify that they saw the moon before sunset, it is known that they are false witnesses.

Rabbi Zeira said in the name of Rav Naḥman: For twenty-four hours the moon is concealed.

For twenty-four hours the moon is concealed from sight:

And if it happened that the birth was at midday, then:

For us,

for the people of Babylonia, the moon is concealed

six from the old and eighteen from the new.

Six hours before the birth, the moon is concealed from us in the cycle belonging to the preceding month, and eighteen hours after the birth, the moon is concealed in the cycle belonging to the coming month.

For the people of Babylonia, who dwell east of the Land of Israel, the sun sets on the final day of the month before it sets in the Land of Israel, and they cannot see the appearance of the moon close to sunset as it appears then in the Land of Israel, six hours after the birth that was at midday.

And therefore the moon is concealed from them during the six hours before the birth, and it does not appear before them until the following morning, eighteen hours after the birth. [Rather, because of the sunlight at sunrise it cannot be discerned ordinarily, but only close to sunset].

Whereas

for them,

for the people of the Land of Israel, which lies west of Babylonia, the moon is concealed

six from the new,

six hours in the cycle belonging to the new month,

and eighteen from the old.

And eighteen hours from the cycle belonging to the old month.

Because the new moon [after the birth] is located at the southwestern corner, which is seen later by the people of the Land of Israel. Therefore it is concealed from them for only six hours, and appears close to sunset. But before the birth, the last time it can appear, and at the time of its rising in the east, it is then far from the Land of Israel, and therefore they do not see it for eighteen hours before the birth.

It follows that in every place the moon is concealed for a total of twenty-four hours.

What practical difference is there

in this matter?

Rav Ashi said: To disprove witnesses.

If the witnesses said that they saw the old moon and the new moon within twenty-four hours, it is known that they are false witnesses.

The Master said,

Rabbi Zeira, above:

There must be a night and a day from the new month.

The old moon must not be seen even at night, the eve of the thirtieth day on which they sanctify the month.

But if it was seen at the beginning of the night, the court cannot sanctify it intentionally on the thirtieth day.

And we inquire about it:

From where do we know

this law?

And we answer:

Rabbi Yoḥanan said:

Because it is stated [Leviticus 23], concerning Yom Kippur:

“From evening to evening

you shall observe your Sabbath.” From here [it follows] that on the festivals the day follows the night [the festival begins at night and ends at the end of the day].

And likewise with Rosh Chodesh: it begins at night. Therefore it is necessary that even the night of Rosh Chodesh should not belong to the preceding month.

Reish Lakish said:

Because it is stated [Exodus 12], concerning the eating of matza on the festival of Passover: “On the first, on the fourteenth day of the month, in the evening, you shall eat matzot,

until the twenty-first day of the month in the evening.”

From here [it follows] that the festival ends at the beginning of the evening. That is, the festivals begin at night and end at the end of the following day.

And we inquire about it:

What is the difference between them,

what is the halakhic difference between them?

Abaye said: The difference between them is the significance of the exposition.

There is no practical halakhic difference between them; rather, they disagree as to from where to expound this matter.

Rava said:

If the moon in the cycle belonging to the preceding month was seen before

midnight,

in this

there is a difference between them.

There is a practical halakhic difference between Rabbi Yoḥanan and Reish Lakish:

According to Rabbi Yoḥanan, who learned that the day follows the night from Yom Kippur, from the beginning of the night the moon belonging to the old cycle must not be seen. For Yom Kippur begins at the beginning of the night, as it is stated: “From evening to evening.”

But according to Reish Lakish, who learned that the day follows the night from the eating of matza, the beginning of the night does not belong to Rosh Chodesh until midnight.

For the verse says: “On the first [of Nisan], on the fourteenth day of the month, in the evening, you shall eat matzot, until the twenty-first day of the month in the evening.”

And this verse speaks of optional eating during the seven days of Passover, for there is no obligation to eat matza except on the first night alone.

And on the first night of Passover, when eating matza is obligatory, it is eaten together with the Passover offering, concerning which it is stated: “And they shall eat the flesh on this night; with matzot and bitter herbs they shall eat it,” and the Passover offering may be eaten until midnight.

And since the Passover offering is slaughtered on the fourteenth day of Nisan, its eating, and the eating of the matza together with it, belong to the fourteenth day, on which the Passover offering was slaughtered.

From here it follows that only from midnight is the eating of matza considered to belong to the fifteenth of Nisan, which is the first festival day of Passover.

Therefore, according to Reish Lakish, if the old moon was not seen until after midnight, if the court wished to threaten the witnesses on the following day that they should testify that they saw the renewal of the moon, in order to sanctify it before its proper time and thereby distance Yom Kippur from Shabbat, they are permitted to do so.

Rabbi Zeira said in the name of Rav Naḥman:

Outside the Land of Israel, where they do not know when the court will sanctify the month, they observe two festival days because of the uncertainty.

And

every uncertainty—

we cast it forward!

Every second festival day that they observe because of the uncertainty is observed on the day after the date written in the Torah, according to the calendar followed outside the Land of Israel on the basis of calculation.

For example: the first festival day of Passover, which is on the fifteenth of Nisan, is observed on the fifteenth and sixteenth according to their calculation.

And likewise the first festival day of Sukkot, which is on the fifteenth of Tishrei, is observed on the fifteenth and sixteenth.

[Outside the Land of Israel they calculated the calendar on the assumption that Elul and Adar are deficient, while the other months are generally made alternately full and deficient, as we calculate today by means of calculation.]

And Rav Naḥman came

to say,

to state,

that we observe the fifteenth and sixteenth.

But

we do not observe the fourteenth.

For they observe only the fifteenth and sixteenth as festival days, but not the fourteenth preceding them.

And we raise an objection:

Then let us also observe the fourteenth,

let them also make the fourteenth a festival day,

perhaps

[lest]

they made Av deficient and they made Elul deficient.

But we, the people outside the Land of Israel, consider Av to be an intercalated month [and Elul deficient], and it follows that on the thirtieth day of Elul, on which Rosh Hashanah falls according to our calculation, it was already the second of Tishrei in the Land of Israel [and their Rosh Hashanah fell one day earlier].

Therefore it is necessary to observe also the fourteenth of Tishrei as a festival day, because it falls on the fifteenth in the Land of Israel.

And likewise concerning Nisan, one must be concerned lest in the Land of Israel they made Shevat deficient, whereas the people outside the Land of Israel consider Shevat an intercalated month.