20 18: 365 days and 52 weeks.

The time generally used in China is calculated according to the solar calendar and the lunar calendar. The calculation methods of solar calendar year and lunar calendar year are different. Gregorian calendar, 365 days a year (366 days in leap year). In the lunar calendar, the number of days in a year fluctuates between 12 months and 13 months due to leap months. Look at the calendar. How many days are there in 20 18?

Q: How many days and weeks are there on 20 18?

A: 20 18 has 365 days and * * * has 52 weeks 1 day.

A year is a vague concept, and the detailed distinction can be divided into the following categories:

1, solar year

The current Gregorian calendar is 365 days a year (366 days in leap years), and one day (called solar day) is 24 hours, 60 minutes each time and 60 seconds each time;

2. Lunar New Year

Due to leap months, the number of days in a year fluctuates between 12 months and 13 months.

3. The year of return

Seen from the earth, the time for the sun to circle the ecliptic of the celestial sphere, that is, the time from the vernal equinox to the vernal equinox, is also called the "solar year". The return year is about 20 minutes and 23 seconds shorter than the sidereal year, and the average return day is 365.2422 or 365 days at 5: 48: 46.

4. sidereal year

The time required for the earth to make one revolution around the sun. Only used in astronomy, not in calendar. Due to precession (the age difference of the earth's rotation axis makes vernal equinox slowly move westward along the ecliptic at a speed of 50.24 arc seconds per year, which is caused by this phenomenon), the sidereal year is about 20 minutes and 23 seconds longer than the tropic of cancer. It is equal to 365.25636 average solar days, that is, 365 days 6: 9: 9.5 seconds.

The above figures are not absolutely accurate, because the rotation speed of the earth around the sun is not uniform, so there are still some errors every year, which can be corrected by astronomical observation!