What is the mean length of the year in the Gregorian calendar?
- A.365.2422 days
- B.365.2425 days
- C.365.25 days
- D.365.5 days
Correct answer
Explanation
The correct answer is B, 365.2425 days. The Gregorian cycle of 400 years contains 97 leap years, so it holds 146,097 days, and dividing that by 400 gives exactly 365.2425 days for the mean year. Option A, 365.2422 days, is the true tropical year, the interval between successive vernal equinoxes, and it is a deliberate near miss: the small difference between the two figures is why the Gregorian calendar gains only about one day in three thousand years. Option C, 365.25 days, is the mean Julian year, which came from adding one leap day in every four years with no exception, and it was eleven minutes too long. Option D, 365.5 days, matches no calendar at all. Candidates should be able to place all three figures: 365.2422 in nature, 365.2425 in the Gregorian rule and 365.25 in the Julian rule.
Read the full article: Gregorian Calendar, Leap Years, Solstices and Equinoxes
Practice Questions
View allWho introduced the Gregorian calendar, which is in civil use across most of the world today?
- A.Julius Caesar
- B.Pope Gregory XIII
- C.Sosigenes of Alexandria
- D.Emperor Augustus
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He issued the bull Inter gravissimas in February 1582 and the new calendar took effect that October, correcting the drift that had built up in the older system and tightening the rule for leap years.
Read the full explanation →How many days were omitted from the calendar when the Gregorian reform came into force in October 1582?
- A.7 days
- B.10 days
- C.11 days
- D.13 days
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Thursday, 4 October 1582 was followed immediately by Friday, 15 October 1582, so ten dates vanished while the sequence of weekdays continued unbroken; the correction was needed because the Julian year of 365.25 days was about eleven minutes too long and had pushed the spring equinox ten days out of…
Read the full explanation →Which of the following is NOT a leap year?
- A.1600
- B.2000
- C.1900
- D.2400
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Under the Gregorian rule a year divisible by four is a leap year, but a century year is a leap year only if it is also divisible by 400.
Read the full explanation →The Gregorian calendar was introduced to correct the errors of which earlier calendar?
- A.The Julian calendar
- B.The Saka calendar
- C.The Hijri calendar
- D.The Vikram Samvat
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The Julian calendar, in use from 46 BC, assumed a year of exactly 365.25 days, which is about eleven minutes longer than the true tropical year of roughly 365.2422 days, so it gained a day about every 128 years and the equinox slid out of place.
Read the full explanation →Which of the following calendars will be the same as the calendar for the year 2003?
- A.2014
- B.2013
- C.2012
- D.2011
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A year repeats another year's calendar when the odd days between them add up to a multiple of seven and both years are of the same kind, ordinary or leap.
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