On May 20, 2006, at 32: 03, the formation and influence of the tilt of the earth's axis elected by voters: At present, the known change period of the tilt of the earth's axis is about 40,000 years, ranging from 22. 1 to 24.5 degrees, and the current tilt is 23.5 degrees. According to scientists, four billion years ago, an asteroid hit the earth, causing the earth's axis to tilt, thus producing the four seasons climate of the earth. (Another way of saying it: /mrbosh/wbook/gqy07.htm) In fact, among the nine planets in the solar system, all the other planets are more or less inclined except Mercury, which is almost perpendicular to the ecliptic. For example, Mars tilts 25 degrees, Saturn tilts 27 degrees, Jupiter tilts 3 degrees, and even our sun tilts 7 degrees, the moon tilts 6.5 degrees, and Uranus tilts as high as 98 degrees. As we all know, the earth revolves around the sun in an inclined posture, so there are four seasons in the northern hemisphere and the southern hemisphere. At present, it is known that the change period of the inclination of the earth axis is about 40 thousand years, ranging from 22. 1 to 24.5 degrees, and now the inclination is 23.5 degrees. If the inclination angle becomes larger, the sunshine amount in the southern hemisphere and the northern hemisphere will increase greatly in summer and decrease sharply in winter. In addition, there are other orbital factors that affect the earth's climate, such as the eccentricity of the earth's orbital ellipse, whose variation period is about 654.38+ million years. Of the nine planets in the solar system, except Mercury, which is almost perpendicular to the ecliptic plane, all the other planets are more or less inclined. For example, Mars tilts at 25 degrees, Saturn tilts at 27 degrees, Jupiter tilts at 3 degrees, even our sun tilts at 7 degrees, the moon tilts at 6.5 degrees, and Uranus tilts as high as 98 degrees, which is nothing to do! Why are the inclinations of the planets so different? The reason may be that at the beginning of the formation of the solar system, planets were hit by asteroids at different angles and speeds, resulting in different degrees of tilt. Is the current climate caused by space impact? Tracing back to 4 billion years ago, an asteroid hit the earth, which caused the earth's axis to tilt, thus producing the four seasons climate of the earth. Then I went back to Yucatan 65 million years ago. A meteorite hit the earth, which may have led to the extinction of dinosaurs. Because the earth is tilted by 23.5 degrees, the area where sunlight directly hits the earth will change with the position of the earth in the orbit of revolution. In summer, the sun shines directly on the northern hemisphere, which makes the temperature in the northern hemisphere higher, forming summer, while the southern hemisphere gets less energy because of oblique sunlight, so the temperature is lower, forming winter. Half a year later, the sun shines directly in the southern hemisphere and obliquely in the northern hemisphere, so the seasons are reversed. It is summer in the southern hemisphere and winter in the northern hemisphere. Why does the earth's temperature change have a great cycle phenomenon of glacial and interglacial periods? And why the cycle period is not fixed? Generally speaking, the "orbit eccentricity theory" of the earth put forward by Yugoslav mathematician Milankovic in 1930 is very reasonable. The fundamental source of the earth's temperature is solar radiation, so the change of sunshine caused by the change of the distance between the earth and the sun is bound to be the fundamental reason of the ice age and interglacial cycle, especially in the high latitudes of the northern hemisphere, with the periodic change of orbital factors. If the earth is not inclined, but upright, then the sun will shine directly on the equator, which makes the temperature in the area closer to the equator higher and the temperature in the area farther away from the equator lower. No matter where the earth rotates, the temperature will not change much. So hot places are always hot, and cold places are always cold. Of course, the four seasons have not changed! As the earth revolves around the sun, the rotation axis of the earth is influenced by the gravity of the sun and the moon and makes a conical motion in the air. This is the so-called precession phenomenon in physics, which produces "precession". Gyro self-rotating shaft is a typical precession phenomenon. To put it simply, precession is the phenomenon that the rotating shaft rotates in circles (just like the gyro inclines and rotates before landing), and the precession period of the earth is about 26,000 years; Precession is precession, and the two names are different because precession is a physical term, while precession is an astronomical usage. A function related to precession, called nutation, is a phenomenon that the earth's rotation axis swings slightly during precession. These two effects are caused by the tilt of the celestial body's rotation axis, the shape change caused by its rotation and the change of the position of the surrounding celestial bodies. The precession phenomenon makes the earth's axis turn once at the pole of the ecliptic, with a period of about 25,800 years, and the average annual vernal equinox retreats by 50 arc seconds; Now the sun runs on the ecliptic every month, which is different from astrology invented more than 3000 years ago. Polaris is also moving gradually. 14000 years later, Vega will become the North Star.