Jewish Standard Time: Understanding the Hebrew Calendar

How do we determine the lengths of the months?

וְדָבָר זֶה הֲלָכָה לְמשֶׁה מִסִּינַי הוּא. שֶׁבִּזְמַן שֶׁיֵּשׁ סַנְהֶדְרִין קוֹבְעִין עַל פִּי הָרְאִיָּה; וּבִזְמַן שֶׁאֵין שָׁם סַנְהֶדְרִין קוֹבְעִין עַל פִּי הַחֶשְׁבּוֹן הַזֶּה שֶׁאָנוּ מְחַשְּׁבִין בּוֹ הַיּוֹם וְאֵין נִזְקָקִין לִרְאִיָּה...

Mishneh Torah, Sanctification of the New Month 5:2

And this matter is a law of Moses from Sinai: That at a time that there is a Sanhedrin, we set [the new month] by sighting; and when the Sanhedrin does not exist, we set [it] according to this calculation that we [use] to calculate today, and we are not concerned about the sighting...

בראשית א׳:ט״ז-י״ח

(טז) וַיַּ֣עַשׂ אֱלֹקִ֔ים אֶת־שְׁנֵ֥י הַמְּאֹרֹ֖ת הַגְּדֹלִ֑ים אֶת־הַמָּא֤וֹר הַגָּדֹל֙ לְמֶמְשֶׁ֣לֶת הַיּ֔וֹם וְאֶת־הַמָּא֤וֹר הַקָּטֹן֙ לְמֶמְשֶׁ֣לֶת הַלַּ֔יְלָה וְאֵ֖ת הַכּוֹכָבִֽים׃ (יז) וַיִּתֵּ֥ן אֹתָ֛ם אֱלֹקִ֖ים בִּרְקִ֣יעַ הַשָּׁמָ֑יִם לְהָאִ֖יר עַל־הָאָֽרֶץ׃ (יח) וְלִמְשֹׁל֙ בַּיּ֣וֹם וּבַלַּ֔יְלָה וּֽלְהַבְדִּ֔יל בֵּ֥ין הָא֖וֹר וּבֵ֣ין הַחֹ֑שֶׁךְ וַיַּ֥רְא אֱלֹקִ֖ים כִּי־טֽוֹב׃

Genesis 1:16-18

(16) God made the two great lights, the greater light to dominate the day and the lesser light to dominate the night, and the stars. (17) And God set them in the expanse of the sky to shine upon the earth, (18) to dominate the day and the night, and to separate light from darkness. And God saw that this was good.

חולין ס׳ ב:ב׳-ד׳

רבי שמעון בן פזי רמי כתיב (בראשית א, טז) ויעש אלקים את שני המאורות הגדולים וכתיב את המאור הגדול ואת המאור הקטן אמרה ירח לפני הקב"ה רבש"ע אפשר לשני מלכים שישתמשו בכתר אחד אמר לה לכי ומעטי את עצמך אמרה לפניו רבש"ע הואיל ואמרתי לפניך דבר הגון אמעיט את עצמי אמר לה לכי ומשול ביום ובלילה אמרה ליה מאי רבותיה דשרגא בטיהרא מאי אהני אמר לה זיל לימנו בך ישראל ימים ושנים אמרה ליה יומא נמי אי אפשר דלא מנו ביה תקופותא דכתיב (בראשית א, יד) והיו לאותות ולמועדים ולימים ושנים זיל ליקרו צדיקי בשמיך (עמוס ז, ב) יעקב הקטן שמואל הקטן (שמואל א יז, יד) דוד הקטן חזייה דלא קא מיתבא דעתה אמר הקב"ה הביאו כפרה עלי שמיעטתי את הירח והיינו דאמר ר"ש בן לקיש מה נשתנה שעיר של ראש חדש שנאמר בו (במדבר כח, טו) לה' אמר הקב"ה שעיר זה יהא כפרה על שמיעטתי את הירח

Chullin 60b:2-4

§ Rabbi Shimon ben Pazi raises a contradiction between two verses. It is written: “And God made the two great lights” (Genesis 1:16), and it is also written in the same verse: “The greater light to rule the day, and the lesser light to rule the night,” indicating that only one was great. Rabbi Shimon ben Pazi explains: When God first created the sun and the moon, they were equally bright. Then, the moon said before the Holy One, Blessed be He: Master of the Universe, is it possible for two kings to serve with one crown? One of us must be subservient to the other. God therefore said to her, i.e., the moon: If so, go and diminish yourself. She said before Him: Master of the Universe, since I said a correct observation before You, must I diminish myself? God said to her: As compensation, go and rule both during the day along with the sun and during the night. She said to Him: What is the greatness of shining alongside the sun? What use is a candle in the middle of the day? God said to her: Go; let the Jewish people count the days and years with you, and this will be your greatness. She said to Him: But the Jewish people will count with the sun as well, as it is impossible that they will not count seasons with it, as it is written: “And let them be for signs, and for seasons, and for days and years” (Genesis 1:14). God said to her: Go; let righteous men be named after you. Just as you are called the lesser [hakatan] light, there will be Ya’akov HaKatan, i.e., Jacob our forefather (see Amos 7:2), Shmuel HaKatan the tanna, and David HaKatan, i.e., King David (see I Samuel 17:14). God saw that the moon was not comforted. The Holy One, Blessed be He, said: Bring atonement for me, since I diminished the moon. The Gemara notes: And this is what Rabbi Shimon ben Lakish says: What is different about the goat offering of the New Moon, that it is stated with regard to it: “For the Lord” (Numbers 28:15)? The Holy One, Blessed be He, said: This goat shall be an atonement for Me for having diminished the size of the moon.

שמות י״ב:א׳-ב׳

(א) וַיֹּ֤אמֶר ה' אֶל־מֹשֶׁ֣ה וְאֶֽל־אַהֲרֹ֔ן בְּאֶ֥רֶץ מִצְרַ֖יִם לֵאמֹֽר׃ (ב) הַחֹ֧דֶשׁ הַזֶּ֛ה לָכֶ֖ם רֹ֣אשׁ חֳדָשִׁ֑ים רִאשׁ֥וֹן הוּא֙ לָכֶ֔ם לְחׇדְשֵׁ֖י הַשָּׁנָֽה׃

Exodus 12:1-2

(1) The LORD said to Moses and Aaron in the land of Egypt: (2) This month shall mark for you the beginning of the months; it shall be the first of the months of the year for you.

רש"י על שמות י״ב:ב׳

(א) החדש הזה. הֶרְאָהוּ לְבָנָה בְּחִדּוּשָׁהּ וְאָמַר לוֹ כְּשֶׁהַיָּרֵחַ מִתְחַדֵּשׁ יִהְיֶה לְךָ רֹאשׁ חֹדֶשׁ (מכילתא). וְאֵין מִקְרָא יוֹצֵא מִידֵי פְשׁוּטוֹ, עַל חֹדֶשׁ נִיסָן אָמַר לוֹ, זֶה יִהְיֶה רֹאשׁ לְסֵדֶר מִנְיַן הֶחֳדָשִׁים, שֶׁיְּהֵא אִיָּר קָרוּי שֵׁנִי, סִיוָן שְׁלִישִׁי: (ב) הזה. נִתְקַשָּׁה מֹשֶׁה עַל מוֹלַד הַלְּבָנָה, בְּאֵיזוֹ שִׁעוּר תֵּרָאֶה וְתִהְיֶה רְאוּיָה לְקַדֵּשׁ, וְהֶרְאָה לוֹ בְּאֶצְבַּע אֶת הַלְּבָנָה בָּרָקִיעַ וְאָמַר לוֹ כָּזֶה רְאֵה וְקַדֵּשׁ (שם). וְכֵיצַד הֶרְאָהוּ? וַהֲלֹא לֹא הָיָה נִדְבָּר עִמּוֹ אֶלָּא בַּיּוֹם? שֶׁנֶּ' "וַיְהִי בְּיוֹם דִּבֶּר ה'" (שמות ו'), "בְּיוֹם צַוֹּתוֹ" (ויקרא ז'), "מִן הַיּוֹם אֲשֶׁר צִוָּה ה' וָהָלְאָה" (במדבר ט"ו)? אֶלָּא סָמוּךְ לִשְׁקִיעַת הַחַמָּה נֶאֶמְרָה לוֹ פָרָשָׁה זוֹ וְהֶרְאָהוּ עִם חֲשֵׁכָה:

Rashi on Exodus 12:2

(1) החדש הזה — He showed him the moon in the first stage of its renewal, and He said to him, “The time when the moon renews itself thus, shall be unto you the beginning of the month”. (The translation therefore is: “This stage of renewal (חדש) shall be the moment of beginning the months”; cf. Mekhilta d'Rabbi Yishmael 12:2:2). But no Scriptural verse can lose its literal meaning, and He really spoke this in reference to the month Nisan: this month shall be the beginning in the order of counting the months, so that Iyar shall be called the second, Sivan the third. (2) הזה THIS [STAGE OF RENEWAL] — Moses was in perplexity regarding the Molad of (the exact moment when begins) the new moon — how much of it must be visible before it is proper to consecrate it as new moon: He therefore pointed it out to him in the sky with the finger and said to him, “Behold it like this, and consecrate it” (i. e., when you see the moon in a stage of renewal similar to this which you now behold you may proclaim that a new month has begun). But how could He point it out to him, for did He not conserve with him only by day, as it is said, (Exodus 6:28) “And it came to pass on the day when the Lord spake [unto Moses]”; (Leviticus 7:38) “On the day when he commanded”; (Numbers 15:23) “From the day that the Lord commanded and henceforward”? But the explanation is: This chapter was spoken to him close to sunset and He pointed it out to him at nightfall (more lit., near darkness) (Mekhilta d'Rabbi Yishmael 12:2:1).

ספורנו על שמות י״ב:ב׳:א׳

(א) החדש הזה לכם ראש חדשים מכאן ואילך יהיו החדשים שלכם, לעשות בהם כרצונכם, אבל בימי השעבוד לא היו ימיכם שלכם, אבל היו לעבודת אחרים ורצונם, לפיכך ראשון הוא לכם לחדשי השנה. כי בו התחיל מציאותכם הבחיריי:

Sforno on Exodus 12:2:1

(1) החודש הזה לכם ראש חדשים, from now on these months will be yours, to do with as you like. [you have My authority to organise your own calendar. Ed.] This is by way of contrast to the years when you were enslaved when you had no control over your time or timetable at all. [Freedom, i.e. retirement from the “rat race,” means being able to formulate one’s own timetable. Ed.] While you were enslaved, your days, hours, minutes even, were always at the beck and call of your taskmasters.

דברים ט״ז:א׳

(א) שָׁמוֹר֙ אֶת־חֹ֣דֶשׁ הָאָבִ֔יב וְעָשִׂ֣יתָ פֶּ֔סַח לַה' אֱלֹקֶ֑יךָ כִּ֞י בְּחֹ֣דֶשׁ הָֽאָבִ֗יב הוֹצִ֨יאֲךָ֜ ה' אֱלֹקֶ֛יךָ מִמִּצְרַ֖יִם לָֽיְלָה׃

Deuteronomy 16:1

(1) Observe the month of Abib and offer a passover sacrifice to the LORD your God, for it was in the month^-a of Abib, at night, that the LORD your God freed you from Egypt.

רש"י על דברים ט״ז:א׳

(א) שמור את חדש האביב. מִקֹּדֶם בּוֹאוֹ שְׁמֹר שֶׁיְּהֵא רָאוּי לְאָבִיב – לְהַקְרִיב בּוֹ אֶת מִנְחַת הָעֹמֶר, וְאִם לָאו עַבֵּר אֶת הַשָּׁנָה (עי' סנהדרין י"א): (ב) ממצרים לילה. וַהֲלֹא בַּיּוֹם יָצְאוּ שֶׁנֶּאֱמַר (במדבר ל"ג) מִמָּחֳרַת הַפֶּסַח יָצְאוּ בְנֵי יִשְׂרָאֵל וְגוֹ'? אֶלָּא לְפִי שֶׁבַּלַּיְלָה נָתַן לָהֶם פַּרְעֹה רְשׁוּת לָצֵאת, שֶׁנֶּאֱמַר (שמות י"ב) וַיִּקְרָא לְמֹשֶׁה וּלְאַהֲרֹן לַיְלָה וְגוֹ' (בראשית ט'):

Rashi on Deuteronomy 16:1

(1) שמור את חדש האביב WATCH THE MONTH OF ABIB — This means: Before it comes watch whether it will be capable of producing ripe ears (אביב), so that one may offer the Omer meal-offering during it, and if not (i.e. if you observe that the ears will not be ripe by the 16th of Nisan), then intercalate the year (i.e. add a month to the winter-period, so that the month Abib falls later than it otherwise would, by which time the ears will be ripened) (cf. Sanhedrin 11b and Note 4 on p. 191 of Leviticus in the Silbermann edition of the Pentateuch). (2) ממצרים לילה [FOR IN THE MONTH OF ABIB THE LORD THY GOD BROUGHT THEE FORTH] FROM EGYPT BY NIGHT — But did they not go forth by day , as it is said, (Numbers 30:3) “on the morrow after the Passover the children of Israel went out … [in the sight of all the Egyptians]”? But it states that they went out by night because Pharaoh gave them permission to go forth by night, as it is said, (Exodus 12:31) “And he called for Moses and Aaron by night, [and said, Rise up, go forth from among my people etc.]” (cf. Sifrei Devarim 128:5; Berakhot 9a).

סנהדרין י״א ב:ה׳

תנו רבנן על שלשה דברים מעברין את השנה על האביב ועל פירות האילן ועל התקופה על שנים מהן מעברין ועל אחד מהן אין מעברין

Sanhedrin 11b:5

§ The Sages taught in a baraita (Tosefta 2:2): The court may intercalate the year for three matters: For the ripening of the grain, if it is not yet time for the barley to ripen; for the fruit of the trees, if they have not yet ripened; and for the equinox, i.e., to ensure that the autumnal equinox will precede Sukkot. If two of these concerns apply, the court intercalates the year even if the third factor does not apply; but for only one of them the court does not intercalate the year.

ספורנו על דברים ט״ז:א׳

(א) שמור את חדש האביב שמור בהתמדת השגחה שיהי' ניסן חדש האביב ע''י עבורי החדשים והשנים שיכוונו בהם שני הלבנה עם שני החמה: (ב) ועשית פסח בערב חג המצות: (ג) כי בחדש האביב הוציאך כיון ורצה שתהיה יציאתך בעת שנשלם החדש של אביב והוא הנגוד בהיות טלה אלקי מצרים עם השמש בגבורתו והירח בנגודו: (ד) לילה כי אותו הנגוד היה אז בלילה ובהיות שאין קרבן בלילה הוצרך להקדים הקרבתו ביום הקודם לאותו הנגוד ולזכרון זה קבע כן לדורות:

Sforno on Deuteronomy 16:1

(1) שמור את חודש האביב, make sure that the month of Nissan always occurs in the spring, by manipulating the calendar, if necessary and inserting an extra month of Adar. By doing this the solar orbit (year) and the lunar orbits, (12 moons equaling a year) can be brought into line with each other. (2) ועשית פסח, on the first evening of the festival of matzot (3) כי בחודש האביב הוציאך, because it was G’d’s will that your departure from Egypt should be at the time when the month signaling the beginning of spring should occur, astrologically a time when the zodiac sign of the lamb ascends in tandem with the sun, and is opposite the moon, the latter symbolising the Jewish people, as opposed to the Egyptians who worship the sun as a major deity. (4) לילה, on that occasion, the sun/lamb being opposite the moon occurred at night. Seeing that one cannot offer a sacrifice at night, the Torah arranged for the Passover to be offered on the afternoon preceding that night. As a commemoration of that event, it was decided not to change the time of offering the Passover even though the astrological/astronomical data change from year to year.

How many months are in a year?

Types of Yearly Calendars

Solar
- It takes the earth 365.24 days to complete an orbit around the sun.
- Add an extra day every 4th year in order to make every year consist of a complete number of days.
  - (365 x 3 + 366) / 4 = 365.25 ≈ 365.24 days per year
Lunar
- Average of 29.5 days per month (based on how long it takes the moon to orbit Earth, on average)
- 12 months per year x 29.5 days per month = 354 days per year
Lunisolar
- A combination of a lunar and solar calendar...

What type of calendar does Judaism use?

משנה תורה, הלכות קידוש החודש א׳:א׳

(א) חָדְשֵׁי הַשָּׁנָה הֵם חָדְשֵׁי הַלְּבָנָה שֶׁנֶּאֱמַר (במדבר כח יד) "עלַת חֹדֶשׁ בְּחָדְשׁוֹ" וְנֶאֱמַר (שמות יב ב) "הַחֹדֶשׁ הַזֶּה לָכֶם רֹאשׁ חֳדָשִׁים". כָּךְ אָמְרוּ חֲכָמִים הֶרְאָה לוֹ הַקָּדוֹשׁ בָּרוּךְ הוּא לְמשֶׁה בְּמַרְאֵה הַנְּבוּאָה דְּמוּת לְבָנָה וְאָמַר לוֹ כָּזֶה רְאֵה וְקַדֵּשׁ. וְהַשָּׁנִים שֶׁאָנוּ מְחַשְּׁבִין הֵם שְׁנֵי הַחַמָּה שֶׁנֶּאֱמַר (דברים טז א) "שָׁמוֹר אֶת חֹדֶשׁ הָאָבִיב":

Mishneh Torah, Sanctification of the New Month 1:1

(1) The months of the year are lunar months, as it is stated (Numbers 28:14), "the monthly burnt-offering for each new moon"; and it is [also] stated (Exodus 12:2), "This month shall be for you the beginning of the months." Thus did the Sages say: The Holy One, blessed be He, showed Moshe a likeness of the moon in a prophetic vision and said to him, "See [when] it is like this, and sanctify it (as the beginning of the month)." But the years that we calculate are solar years, as it is stated (Deuteronomy 16:1), "Guard the month of the Spring."

משנה תורה, הלכות קידוש החודש א׳:ב׳

(ב) וְכַמָּה יְתֵרָה שְׁנַת הַחַמָּה עַל שְׁנַת הַלְּבָנָה קָרוֹב מֵאַחַד עָשָׂר יוֹם. לְפִיכָךְ כְּשֶׁיִּתְקַבֵּץ מִן הַתּוֹסֶפֶת הַזֹּאת כְּמוֹ שְׁלֹשִׁים יוֹם אוֹ פָּחוֹת מְעַט אוֹ יוֹתֵר מְעַט מוֹסִיפִין חֹדֶשׁ אֶחָד וְעוֹשִׂין אוֹתָהּ הַשָּׁנָה שְׁלֹשָׁה עָשָׂר חֹדֶשׁ וְהִיא הַנִּקְרֵאת שָׁנָה מְעֵבֶּרֶת. שֶׁאִי אֶפְשָׁר לִהְיוֹת הַשָּׁנָה שְׁנֵים עָשָׂר חֹדֶשׁ וְכָךְ וְכָךְ יָמִים שֶׁנֶּאֱמַר (שמות יב ב) "לְחָדְשֵׁי הַשָּׁנָה". חֳדָשִׁים אַתָּה מוֹנֶה לְשָׁנָה וְאֵין אַתָּה מוֹנֶה יָמִים:

Mishneh Torah, Sanctification of the New Month 1:2

(2) The solar year exceeds the lunar year by eleven days, approximately. Hence, whenever this excess accumulates to about thirty days, somewhat more or less, one month is added and the year is made up of thirteen months and is called leap year. The year cannot consist of twelve months plus several days, because it is written: "Months of the year" (Exodus 12:2), implying that the year should be reckoned by months and not by days.

365 ≠ 354
If we add a leap month of 30 days 7 times in a 19-year cycle,
( ( (354 + 30) x 7) + 354 x 12) / 19 ≈ 365
then the lunar months will align consistently with the seasons of the solar year.
*Disclaimer: A Jewish non-leap year can have 353, 354, or 355 days, and a Jewish leap year can have 383, 384, or 385 days. The equations above are purely to explain the concept of the Jewish leap year.

Why is it so important that the solar year and lunar year align?

משנה תורה, הלכות קידוש החודש ד׳:א׳

(א) שָׁנָּה מְעֻבֶּרֶת הִיא שָׁנָה שֶׁמּוֹסִיפִין בָּהּ חֹדֶשׁ. וְאֵין מוֹסִיפִין לְעוֹלָם אֶלָּא אֲדָר וְעוֹשִׂין אוֹתָהּ שָׁנָה שְׁנֵי אֲדָרִין אֲדָר רִאשׁוֹן וַאֲדָר שֵׁנִי. וּמִפְּנֵי מָה מוֹסִיפִין חֹדֶשׁ זֶה מִפְּנֵי זְמַן הָאָבִיב כְּדֵי שֶׁיְּהֵא הַפֶּסַח בְּאוֹתוֹ זְמַן שֶׁנֶּאֱמַר (דברים טז א) "שָׁמוֹר אֶת חֹדֶשׁ הָאָבִיב" שֶׁיִּהְיֶה חֹדֶשׁ זֶה בִּזְמַן הָאָבִיב. וְלוּלֵא הוֹסָפַת הַחֹדֶשׁ הַזֶּה הַפֶּסַח בָּא פְּעָמִים בִּימוֹת הַחַמָּה וּפְעָמִים בִּימוֹת הַגְּשָׁמִים:

Mishneh Torah, Sanctification of the New Month 4:1

(1) A leap year is a year to which an extra month is added. Only Adar is the month that is ever added, so that a leap year has two months of Adar: a first Adar and a second Adar. Why is just this month added? Because of the spring season, so that Pesaḥ should be observed during the barley season, as it is written: "Observe the month of Aviv, and keep the Passover…" (Deuteronomy 16:1), implying that this month of Nisan should occur during the spring. Without the addition of this month of Adar, Passover would occur sometimes in the summer and sometimes in the rainy season [of winter].

שמות חקלאיים לשלושת הרגלים

פסח - חג האביב

שבועות - חג הקציר & חג הביכורים

סוכות - חג האסיף

Agricultural Names for Shalosh Regalim

Pesach - Chag HaAviv

Shavuot - Chag HaKatzir & Chag HaBikurim

Sukkot - Chag HaAsif

Which Adar do we celebrate Purim in?

אסתר ט׳:כ׳-כ״ב

(כ) וַיִּכְתֹּ֣ב מָרְדֳּכַ֔י אֶת־הַדְּבָרִ֖ים הָאֵ֑לֶּה וַיִּשְׁלַ֨ח סְפָרִ֜ים אֶל־כָּל־הַיְּהוּדִ֗ים אֲשֶׁר֙ בְּכָל־מְדִינוֹת֙ הַמֶּ֣לֶךְ אֲחַשְׁוֵר֔וֹשׁ הַקְּרוֹבִ֖ים וְהָרְחוֹקִֽים׃ (כא) לְקַיֵּם֮ עֲלֵיהֶם֒ לִהְי֣וֹת עֹשִׂ֗ים אֵ֠ת י֣וֹם אַרְבָּעָ֤ה עָשָׂר֙ לְחֹ֣דֶשׁ אֲדָ֔ר וְאֵ֛ת יוֹם־חֲמִשָּׁ֥ה עָשָׂ֖ר בּ֑וֹ בְּכָל־שָׁנָ֖ה וְשָׁנָֽה׃ (כב) כַּיָּמִ֗ים אֲשֶׁר־נָ֨חוּ בָהֶ֤ם הַיְּהוּדִים֙ מֵא֣וֹיְבֵיהֶ֔ם וְהַחֹ֗דֶשׁ אֲשֶׁר֩ נֶהְפַּ֨ךְ לָהֶ֤ם מִיָּגוֹן֙ לְשִׂמְחָ֔ה וּמֵאֵ֖בֶל לְי֣וֹם ט֑וֹב לַעֲשׂ֣וֹת אוֹתָ֗ם יְמֵי֙ מִשְׁתֶּ֣ה וְשִׂמְחָ֔ה וּמִשְׁל֤וֹחַ מָנוֹת֙ אִ֣ישׁ לְרֵעֵ֔הוּ וּמַתָּנ֖וֹת לָֽאֶבְיוֹנִֽים׃

Esther 9:20-22

(20) Mordecai recorded these events. And he sent dispatches to all the Jews throughout the provinces of King Ahasuerus, near and far, (21) charging them to observe the fourteenth and fifteenth days of Adar, every year— (22) the same days on which the Jews enjoyed relief from their foes and the same month which had been transformed for them from one of grief and mourning to one of festive joy. They were to observe them as days of feasting and merrymaking, and as an occasion for sending gifts to one another and presents to the poor.

מגילה ו׳ ב:י״ג

מתני׳ קראו את המגילה באדר הראשון ונתעברה השנה, קורין אותה באדר שני...

Megillah 6b:13

MISHNA: If the people read the Megilla during the first Adar and subsequently the year was then intercalated by the court and now the following month will be the second Adar, one reads the Megilla again during the second Adar...

מגילה ו׳ ב:כ״ז

אמר רבי טבי: טעמא דרבי שמעון בן גמליאל מסמך גאולה לגאולה עדיף

Megillah 6b:27

Rabbi Tavi said: The reason for the opinion of Rabban Shimon ben Gamliel is that juxtaposing the celebration of one redemption, Purim, to the celebration of another redemption, Passover, is preferable.

רש"י על מגילה ו׳ ב:כ״ז:א׳

גאולה לגאולה - פורים לפסח:

Rashi on Megillah 6b:27:1

...

What happens on the 14th and 15th of Adar Rishon during a Jewish leap year?

Fun fact: This is the last Siman and Seif of Shulchan Aruch Orach Chaim:

אורח חיים תרצ״ז:א׳

(א) אין אומרים תחנה בי"ד וט"ו שבאדר ראשון ודין תענית והספד בהן ובו סעיף אחד:
יום י"ד וט"ו שבאדר ראשון אין נופלין על פניהם ואין אומרים מזמור יענך ה' ביום צרה ואסורים בהספד ותענית אבל שאר דברים אין נוהגים בהם וי"א דאף בהספד ותענית מותרים: הגה והמנהג כסברא ראשונה. י"א שחייב להרבות במשתה ושמחה בי"ד שבאדר ראשון (טור בשם הרי"ף) ואין נוהגין כן מ"מ ירבה קצת בסעודה כדי לצאת ידי המחמירים (הג"מ בשם סמ"ק) וטוב לב משתה תמיד:

Shulchan Arukh, Orach Chayim 697:1

(1) The day of the 14th and the 15th of the First month of Adar [in a leap year] we do not fall upon our faces [recite tahanun] and we do not say (the Psalm) a song - Hashem will answer you on a day of suffering, and on them [the 14th and 15th of Adar I] it is forbidden to eulogize or fast. There are those who say that even eulogies and fasting is permitted. Rema: the practice is according to the first understanding. There are those who say that one is obligated to increase in joy and feasting on the 14th of Adar I however this is not the practice. Nonetheless one should increase slightly their joy and feasting in order to fulfill the words of those who are stringent 'But he that is of a merry heart hath a continual feast (Proverbs 15:15).'

Some Hashkafa / a message / something to think about...

ברכות בקידוש ובעמידה

"...מקדש השבת."

"...מקדש ישראל והזמנים."

"...מקדש ישראל וראשי חדשים."

Kiddush and Amida Brachot

"...Mekadesh Hashabbat."

"...Mekadesh Yisrael V'Hazmanim."

"...Mekadesh Yisrael V'Roshei Chadashim."

ברכות מ״ט א:ט׳

״מְקַדֵּשׁ יִשְׂרָאֵל וְהַזְּמַנִּים״! — יִשְׂרָאֵל דְּקַדְּשִׁינְהוּ לִזְמַנִּים. ״מְקַדֵּשׁ יִשְׂרָאֵל וְרָאשֵׁי חֳדָשִׁים״! — יִשְׂרָאֵל דְּקַדְּשִׁינְהוּ לְרָאשֵׁי חֳדָשִׁים.

Berakhot 49a:9

Levi cited two other blessings: Who sanctifies Israel and the seasons. It means: Who sanctifies Israel, who sanctify the seasons. Who sanctifies Israel and the New Moon. It means: Who sanctifies Israel, who sanctify the New Moons.

Kedushat Yom Tov is dependent on human effort.

ויקרא י״ט:ב׳

דַּבֵּ֞ר אֶל־כָּל־עֲדַ֧ת בְּנֵי־יִשְׂרָאֵ֛ל וְאָמַרְתָּ֥ אֲלֵהֶ֖ם קְדֹשִׁ֣ים תִּהְי֑וּ כִּ֣י קָד֔וֹשׁ אֲנִ֖י יְהוָ֥ה אֱלֹהֵיכֶֽם׃

Leviticus 19:2

Speak to the whole Israelite community and say to them: You shall be holy, for I, the LORD your God, am holy.

משנה תורה, הלכות דעות א׳:ו׳

כָּךְ לָמְדוּ בְּפֵרוּשׁ מִצְוָה זוֹ. מַה הוּא נִקְרָא חַנּוּן אַף אַתָּה הֱיֵה חַנּוּן. מַה הוּא נִקְרָא רַחוּם אַף אַתָּה הֱיֵה רַחוּם. מַה הוּא נִקְרָא קָדוֹשׁ אַף אַתָּה הֱיֵה קָדוֹשׁ. וְעַל דֶּרֶךְ זוֹ קָרְאוּ הַנְּבִיאִים לָאֵל בְּכָל אוֹתָן הַכִּנּוּיִין אֶרֶךְ אַפַּיִם וְרַב חֶסֶד צַדִּיק וְיָשָׁר תָּמִים גִּבּוֹר וְחָזָק וְכַיּוֹצֵא בָּהֶן. לְהוֹדִיעַ שֶׁהֵן דְּרָכִים טוֹבִים וִישָׁרִים וְחַיָּב אָדָם לְהַנְהִיג עַצְמוֹ בָּהֶן וּלְהִדַּמּוֹת אֵלָיו כְּפִי כֹּחוֹ:

Mishneh Torah, Human Dispositions 1:6

In explaining this commandment the sages taught thus: Even as He is called gracious, be thou gracious; even as He is called merciful, be thou merciful; even as He is called holy, be thou holy.⁴Shabbat, 133b.; Sotah, 14a. C. In this wise did the prophets attribute to God all such terms as long-suffering, abundant in benificence, just and right, perfect, mighty and powerful and others like these, to proclaim that they are good and straight paths, and that man is obligated to lead himself in them, and to be like unto Him in proportion to his power.

By emulating Hashem, we bring Hashem into our lives.

ראש השנה כ״ה א:ג׳-ד׳

אָמַר רַבִּי דּוֹסָא בֶּן הוֹרְכִּינָס: עֵדֵי שֶׁקֶר הֵן, הֵיאַךְ מְעִידִים עַל הָאִשָּׁה שֶׁיָּלְדָה וּלְמָחָר כְּרֵיסָהּ בֵּין שִׁינֶּיהָ? אָמַר לוֹ רַבִּי יְהוֹשֻׁעַ: רוֹאֶה אֲנִי אֶת דְּבָרֶיךָ. שָׁלַח לוֹ רַבָּן גַּמְלִיאֵל: גּוֹזְרַנִי עָלֶיךָ שֶׁתָּבֹא אֶצְלִי בְּמַקֶּלְךָ וּבִמְעוֹתֶיךָ בְּיוֹם הַכִּפּוּרִים שֶׁחָל לִהְיוֹת בְּחֶשְׁבּוֹנֶךָ. הָלַךְ וּמְצָאוֹ רַבִּי עֲקִיבָא מֵיצֵר, אָמַר לוֹ: יֵשׁ לִי לִלְמוֹד שֶׁכׇּל מַה שֶּׁעָשָׂה רַבָּן גַּמְלִיאֵל עָשׂוּי, שֶׁנֶּאֱמַר: ״אֵלֶּה מוֹעֲדֵי ה׳ מִקְרָאֵי קֹדֶשׁ אֲשֶׁר תִּקְרְאוּ אֹתָם״, בֵּין בִּזְמַנָּן בֵּין שֶׁלֹּא בִּזְמַנָּן — אֵין לִי מוֹעֲדוֹת אֶלָּא אֵלּוּ.

Rosh Hashanah 25a:3-4

Rabbi Dosa ben Horkinas disagreed and said: They are false witnesses; how can witnesses testify that a woman gave birth and the next day her belly is between her teeth, i.e., she is obviously still pregnant? If the new moon was already visible at its anticipated time, how could it not be seen a day later? Rabbi Yehoshua said to him: I see the logic of your statement; the New Moon must be established a day later. Upon hearing that Rabbi Yehoshua had challenged his ruling, Rabban Gamliel sent a message to him: I decree against you that you must appear before me with your staff and with your money on the day on which Yom Kippur occurs according to your calculation; according to my calculation, that day is the eleventh of Tishrei, the day after Yom Kippur. Rabbi Akiva went and found Rabbi Yehoshua distressed that the head of the Great Sanhedrin was forcing him to desecrate the day that he maintained was Yom Kippur. In an attempt to console him, Rabbi Akiva said to Rabbi Yehoshua: I can learn from a verse that everything that Rabban Gamliel did in sanctifying the month is done, i.e., it is valid. As it is stated: “These are the appointed seasons of the Lord, sacred convocations, which you shall proclaim in their season” (Leviticus 23:4). This verse indicates that whether you have proclaimed them at their proper time or whether you have declared them not at their proper time, I have only these Festivals as established by the representatives of the Jewish people.

The Jewish Leap Year
The average length of the synodic month is 29.530589 days. Thus it is convenient if months are in general alternately 29 and 30 days (sometimes termed respectively hollow and full). Hence, the period of 12 lunar months equals 354.37 days.
The Jewish leap year, referred to in Hebrew as Shanah Me'uberet, has 13 months and occurs seven times in a 19-year cycle. There are 29 or 30 days in each month in a Jewish leap year, which has 383, 384, or 385 days.
An extra month, Adar I, is added after the month of Shevat and before the month of Adar in a leap year. The month is also known as Adar Rishon or Adar Alef. According to Jewish tradition, Adar is a lucky and happy month.
A leap year is referred to in Hebrew as Shanah Me'uberet, or a pregnant year. A Jewish leap year occurs 7 times in a 19-year cycle. The 3rd, 6th, 8th, 11th, 14th, 17th, and 19th years are leap years in this cycle.