What do the solar day, sidereal day, sidereal year and tropic year mean respectively, and how long are they?

Solar Day is based on the sun. Sidereal day is based on distant stars (distances are recorded in light years). Both the Sun Day and the sidereal day are the results of rotation and revolution, and the angle formed by the revolution of the earth can be ignored because of the remoteness of the stars.

Manual timers are used in sidereal years and natural timers are used in tropical years. The artificial timer is not affected by the earth tide, while the natural timer in tropical years shortens the time of tropical years (crust surface time) under the action of the earth tide, resulting in time difference, and this accumulated year is precession.

The time of the sidereal year is 10 second at 6: 09 on 365. Because of the earth tide and the gravity of celestial bodies, the time of the tropical year is not fixed. In the year with high gravity, the return year is shorter. A year with less gravity takes longer to return to that year.