Does the distance between the sun and the earth change at different times?

Does the distance between the sun and the earth change at different times?

Now we know that the change of the distance between the sun and the earth in a day is negligible. In the morning, the sun is a little far away from us, and at noon, the difference is about equal to the radius of the earth, which is only 1 / 2300 of the distance between the sun and the earth. This has little effect on the observation of the size of the sun and the heat energy radiated by the sun to the earth

When will the sun be closest to the earth?
When is the sun closest to the earth?

The earth's orbit around the sun is an ellipse with an inclination (degree) of 0.000, an eccentricity of 0.0167 and an inclination of 23.45 degrees. The solar system is a system of celestial bodies constrained by the sun's gravity, The solar system consists of the sun (stars), nine planets (including the earth), numerous asteroids, many satellites (including the moon), comets, meteoroids, a large amount of dust and thin gaseous matter. In the solar system, the mass of the sun accounts for 99.8% of the total mass of the solar system, The sum of other celestial bodies is less than 0.2% of the sun. The sun is the central celestial body, and its gravity controls the whole solar system, making other celestial bodies revolve around the sun. The nine planets in the solar system (mercury, Venus, earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto) are in near circular orbits close to the same plane, Orbit around the sun in the same direction. The distance from the planet to the sun (expressed by a) a = 0.4 + 0.3 * 2n-2 (astronomical units), where n represents the nth planet from near to far (see the table above for details). The rotation periods of earth, Mars, Jupiter, Saturn, Uranus and Neptune are 12 hours to one day, but the rotation periods of mercury, Venus and Pluto are very long, 58.65 days, 243 days and 6.387 days respectively, Most planets have the same direction of rotation and revolution, but Venus has the opposite direction. Except mercury and Venus, all other planets have satellites that rotate around the sun to form a satellite system. Usually, the rotation of the earth around the sun is called the revolution of the earth. To be exact, the rotation of the earth and the sun around the common center of mass of the sun and the earth is just because the mass of the sun is 330000 times that of the earth, Their common center of mass is only about 450 km away from the sun's center of mass, which is insignificant compared with the average distance between the sun and the earth of 1.496 × 108 km. Therefore, people usually only talk about the earth's revolution around the sun, not about the sun's geological center. The direction of the earth's revolution is the same as that of its rotation, that is, from west to East, The closest distance between the earth and the sun is about 1.471 × 108km, and the farthest distance is about 1.521 × 108km. The eccentricity of the ellipse is only 0.0167. The orbit plane of the earth around the sun is called ecliptic plane, and the angle between the ecliptic plane and the equatorial plane of the earth is called "ecliptic angle", At present, it is 23 ° 26 ′ 21 ″. 448. The earth's rotation and revolution are carried out at the same time. The angle between the rotation axis (Earth's axis) and the orbit plane of the revolution is 66 ° 34 ′. No matter where the earth rotates, the tilt angle of the earth's axis remains unchanged. The period of the earth's revolution is one year, If a star is used as a reference point, the time interval between the sun passing through the line between the star and the earth is called stellar year. In fact, it is the length of 360 ° rotation of the earth, with a value of 365.2564 days, which is the real cycle of the earth's revolution, The first regression year is 365.2422 days, which is equal to 5:48:46.08 seconds of 365 days. Because the equinox moves westward 50 ″ every year on the ecliptic, the angle that the sun passes through the equinox is 360 ° - 50 ″. 29 = 359 ° 59 ′ 9 ″. 71, This phenomenon is called precession in astronomy. In the course of the earth's revolution, its revolution speed changes constantly. At perihelion, the speed is the fastest, the angular speed is 1 ° 1'11 ″ / day, and the linear speed is about 30.3km/s; at aphelion, the speed is the slowest, the angular speed is 57'11 ″ / day, and the linear speed is about 29.3km/s, However, due to the change of the earth's revolution speed, the summer half year from the vernal equinox to the autumnal equinox is more than 186 days, while the winter half year from the autumnal equinox to the vernal equinox is only 179 days. The earth's revolution leads to many natural phenomena, such as the change of the height of the earth's midday horizon, the change of the length of day and night on the earth, the change of four seasons, the formation of five zones, etc

What is the season when the earth is closest to the sun?

Winter in the Northern Hemisphere