Why does the sun look as far away in the morning as at noon?

The distance between the sun and the earth is the same in the morning and at noon.

The maximum distance between the earth and the sun is 15 265438+ ten thousand kilometers (the earth is at apohelion); The minimum value is 14 765438+ million kilometers (the earth is at perihelion); The average is1496,000 km; This is an astronomical unit. 1976 was determined by the international astronomical union as 149597870 km, and it was used from 1984. According to this distance, it takes only 8 minutes 18 seconds for sunlight to reach the earth's surface.

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The four seasons of the earth are caused by direct sunlight and oblique sunlight. Because there is an included angle of 23.5 degrees between the earth's orbital plane and the earth's equatorial plane, during the summer solstice, the northern hemisphere of the earth leans towards the sun, and the sun shines directly on the tropic of cancer, so the weather in the northern hemisphere is hot. In addition, the speed of the earth's revolution also has an impact. The speed of the earth's revolution is very fast when it passes the perihelion, and very slow when it passes the perihelion.

According to Kepler's three laws, the earth's orbit around the sun is an ellipse, and the sun is at a focus of this ellipse. The eccentricity of the earth's orbit is 0.0 17, and there is a perihelion and an apohelion in the orbit. The perihelion is 14765438+ 10,000 kilometers away from the sun, and the apohelion is 15265438+ 10,000 kilometers away from the sun, with a difference of 5 million kilometers, about 1/30.

But the difference of 1/30 has also brought obvious benefits to our northern hemisphere. According to the change of precession, this situation will be reversed after 13000 years. Winter in the northern hemisphere passes through apohelion and summer passes through perihelion.

Mercury's perihelion moves on its orbital plane, moving forward every 100 years (called precession in astronomy) by about 560 1 ",which is 43" higher than the value calculated according to Newton's law. This value is called the anomalous precession of Mercury's perihelion. 1859, inspired by the discovery of Neptune, French astronomer Urbain Le Verrier boldly suggested that this phenomenon was caused by the disturbance of an unknown underwater planet to Mercury.