Do we usually use the sidereal year or the tropic year (solar year) to remember the year? What is the standard of revolution?

We usually take the tropical year (solar year) as the standard to record the year, while the revolution takes the sidereal year as the standard.

The tropic year refers to the time required for the sun center to pass through vernal equinox twice in a row, that is, the time required for the earth to revolve around the sun once, which is about 5: 48: 46 in 365 days. This time interval is fixed, but due to the rotation of the earth, the direct point of the sun moves on the ecliptic, resulting in seasonal changes and calendar differences.

The sidereal year refers to the time required for the earth to revolve around the sun once. Due to the compound motion of the earth's rotation and revolution, compared with a star, the actual time required is 6: 09: 10 second on 365. This time interval is more commonly used in astronomy because it can be used to accurately calculate the position and trajectory of the earth.

In a word, tropic year and sidereal year are two different time units, which are used for different purposes. We usually use the tropic year to record the year, while astronomers prefer to use the sidereal year as the standard.