Feasts of יהוה

The year does not turn automatically at a fixed astronomical point. Month 1 — the month of Abib (אָבִיב, "young grain") — begins when two conditions are met simultaneously:

• Aviv barley in Israel — the barley crop must be at the stage called aviv: far enough along to be roasted and offered as the wave-sheaf on Firstfruits (Leviticus 23:10–14). If it is not yet aviv at the 12th new moon, an intercalary month is added before Month 1, keeping the harvest feast in its proper season.
• First visible crescent — the new month begins when witnesses sight the thin crescent after conjunction (as marked on the wheel, ●). This is the same sighting tracked on the New Moon page.

Reference: Exodus 12:2; Exodus 23:15; Deuteronomy 16:1 ("Observe the month of Abib").

Each of the 12 (or 13) months begins at the first sighting of the new crescent moon after conjunction. The small crescents (☽) on the outer edge of the wheel mark these 12 monthly new-moon sightings. Click any crescent to see the Torah commands and Old Testament examples for the New Moon festival.

This is the same event tracked on moon.grafted.in — the predicted visibility of the crescent from Jerusalem.

From the day of Firstfruits (the day after the first weekly Sabbath during Unleavened Bread), count seven complete Sabbaths — 49 days. The fiftieth day, the day after the seventh Sabbath, is Shavuot. Both Firstfruits and Shavuot therefore always fall on the first day of the week (Leviticus 23:11, 15–16).

• Passover — one evening: a meal eaten that night (Ex 12:8)
• Unleavened Bread — 7 days (15th–21st of Month 1)
• Firstfruits — 1 day; always falls on the first day of the week, but its position within the week of Unleavened Bread varies by year
• Feast of Weeks / Shavuot — 1 day; always the first day of the week, 50 days from Firstfruits
• Trumpets / Atonement — 1 day each
• Tabernacles — 8 days (7 days + solemn 8th-day assembly, 15th–22nd of Month 7)
• Sabbath — one day each week (the 7-dot pattern in the hub)