Lessons 3–4 · 2 lessons · U. Jo‘rayev, Q. Usmonov, A. Nurqulov, G. Jo‘rayeva. Tarixdan hikoyalar (Stories from history), Grade 5 (2nd edition). Cho‘lpon Publishing House, Tashkent, 2015
3
From the history of calendars
Textbook: pp. 9–11
GoalExplain what a calendar is, how the Egyptian, Julian and Gregorian calendars differ and how errors were corrected.
New words
calendar · kalendar (taqvim)equinox · tengkunlikJulian calendar · Yuliy kalendariGregorian calendar · Grigorian kalendari
Explanation
“Calendar” is a Latin word; it is a system for counting time in days, weeks, months and years. Our ancestors called it “taqvim”. A year is the time the Earth needs to go once around the Sun: 365 days and about 6 hours. The ancient Egyptians made the first calendar by watching the flood of the Nile: 12 months of 30 days, with 5 festival days added at the end, 365 days in all. Because they ignored the 6 hours, an error of one day built up every 4 years. In 46 BCE the Roman ruler Julius Caesar introduced a new calendar: the year began on 1 January and every fourth year had a 29-day February, making a 366-day year. A small error remained, and by 1582 the gap had reached 10 days, so the spring equinox was drifting away from 21 March. Under Pope Gregory XIII a new calendar, the Gregorian, was introduced: after 4 October 1582 people went straight to 15 October, and it was set that 29 February occurs 97 times in 400 years. Today Uzbekistan and most countries use this calendar.
Worked examples
Egyptian count: 12 × 30 = 360 days, 360 + 5 festival days = 365 days. The real year is 365 days 6 hours, so 4 × 6 = 24 hours: one day was lost every 4 years.
The Gregorian rule: in 400 years there are 400 × 365 = 146,000 days, plus 97 extra days, 146,097 in all. So 29 February occurs 97 times in 400 years.
Class activity
“The missing days”: pupils draw a page for October 1582, writing 15 October right after 4 October, and count how many days dropped out.
Practice
1
What did the ancient Egyptians watch to build their calendar?
The flooding of the Nile.
2
When and by whom was the Julian calendar introduced and what was new in it?
By Julius Caesar in 46 BCE; the year began on 1 January and every 4 years February had 29 days, making a 366-day year.
3
The Egyptian year was 6 hours shorter than the real year. After how many years does an error of 1 day build up?
In 4 years (4 × 6 = 24 hours).
4
Why did the calendar have to be corrected in 1582?
The error in the Julian calendar had grown to 10 days, the spring equinox was drifting from 21 March, and the count of seasons and festivals was going wrong.