In what way can you see the ecliptic on earth? Why?

What is the ecliptic? In ancient times, we often said that "the zodiac is auspicious" refers to the zodiac! The so-called "auspicious day" is the day or time node when the influence of the sun on the earth is beneficial to human survival. Also known as "light track".

The orbit of the sun's annual movement imagined by the ancients. That is, the great circle where the earth's orbital plane around the sun intersects with the celestial sphere. Around 80 BC, China had a clear concept of the ecliptic, and used the ecliptic as the basic circle to measure the position of celestial bodies.

The Book of the Later Han Dynasty quotes the Star Classic, which explains the history of the Han Dynasty: "The zodiac rules lead the ox to a straight fight of 20 degrees at the beginning and 25 degrees at the top (it should be 115 degrees)."

"Hanshu Tianwenzhi": "There is a middle way in the day and nine lines in the month. Zhongdao, ecliptic, Guangming Avenue. Hiroshima is north to Tokyo and near the North Pole; South to Petunia, as far as the North Pole; East to the corner, west to Lu, to the extreme. As for Tokyo from summer solstice, the north is close to the North Pole, so it is very short; Set an eight-foot table, and the landscape (shadow) is five inches and eight minutes long. As for the morning glory in winter, it is far away, so it is very long; Set an eight-foot table, and the scenery is three feet, one inch and four minutes long. In the spring and autumn, it is divided into Lou and Jiao, and it goes to the pole, but it is in the middle; Set an eight-foot table, and the scenery is seven feet, three inches and six minutes long. This day is far away, and the length of the scene is also certain. It's hard to know how far to go, but it's necessary to see the scenery. Those who look at the scenery, so they know the north and south of the sky. "

Textual research on the history of the New Five Dynasties, Sitian: "Those who are ecliptic are also traces of the sun. Half is on the equator and half is outside the equator, which is 24 degrees apart. "

When measuring the shadow of the sun on the ground, we can get the Taiji diagram of the 24 solar terms of the sun's polar shadow.

Twenty-four solar terms, solar polar shadow, Tai Chi map

Figure the daily trajectory of the sky "8"+the shadow of the sun on the ground "Tai Chi map"

Therefore, we will eventually get such a picture: the track map of the "8" day in the sky and the "Tai Chi map" of the sun shadow on the ground. Of course, in fact, the synchronization phenomenon caused by the sun's annual movement cycle is not limited to these, but these two are the most obvious astronomical phenomena!

How can I see the ecliptic on the earth? Let's take "Twenty-four solar terms" and "Zodiac" as examples to see the observation range of the ecliptic and equator:

Zodiac and equator

Twelve stars, because the 24 solar terms are determined according to the different visual positions of the sun on the ecliptic. The ancients divided the balance around the ecliptic into twelve periods, such as astrology and mystery. When the sun runs for a certain time, it is called a solar term (in fact, the twenty-four solar terms represent the twenty-four different positions of the earth in its orbit around the sun). Twelve times correspond to the zodiac. )

Figure Celestial orbits and solar terms of the zodiac in the west.

The yellow line is the ecliptic and the red line is the equator.

From the above picture, we can see that the zodiac signs in the west are distributed on the circular orbit of the Yellow Line, while the zodiac signs in China are located around the "Twenty-four solar terms". The red line in the figure is the celestial equator (that is, the earth's equatorial projection), and the determination of the vernal equinox needs to observe the rising intersection of the ecliptic and the celestial equator.

Figure 12 Zodiac, Zodiac Equator

In the above picture, we can see that there is no celestial equator above the western "ecliptic coordinate system", so there is no celestial equator constellation, so it is naturally impossible to measure the "vernal equinox", and the "0 degree of the ecliptic" starts from the vernal equinox.

Figure 12 Dynamic diagram of the motion of the ecliptic on the celestial sphere.

From this dynamic map, we can see that the zodiac is rotating along the ecliptic. How does the west draw the all-sky star map without celestial-equatorial coordinate system? !

How to measure "winter solstice, vernal equinox and summer solstice" in ancient times?

China knew the concept of the ecliptic in ancient times. Although China is an equatorial coordinate system, it is inevitable to know the ecliptic because of observing the vernal equinox. The determination of the winter solstice is very important for the beginning of the calendar. It's impossible not to know that the vernal equinox and autumnal equinox existed in China during the Western Zhou Dynasty, and these four solar terms have made a preliminary division of the four seasons!

But strangely, the "ecliptic coordinate system" used in the west does not use the "twenty-four solar terms" in the calendar, especially the "dichotomy". How can you know the four seasons without knowing the concept of the four seasons? How to make a calendar? How can there be "ecliptic" or even "ecliptic coordinate system"? I can't help asking, is the ecliptic coordinate system really invented by the west? !

Because the earth's rotation axis (earth axis) is inclined to its orbital plane by 66 34'. This relationship between the earth's rotation and revolution is usually expressed by its complementary angle (23 26') in astronomy and geography, that is, the intersection angle between the equatorial plane and the orbital plane.

However, this intersection angle is difficult to measure in reality. What should we do?

Therefore, we need "celestial equatorial coordinate system", which has actually been mentioned before, and now I will say it again.

Simply put, imagine the sky as an imaginary big ball. All the celestial bodies we see are projections on this big ball, which is called the celestial ball. The projection of the earth's orbit on the celestial sphere is the ecliptic. From the earth's point of view, it is the circle that the sun passes through in the sky. The celestial equator is the projection of the earth's equator on the celestial sphere; The white road is the projection of the moon's trajectory in the sky on the celestial sphere.

The celestial equator is the projection of the earth's equator on the celestial sphere.

Therefore, the earth's equator is projected on the celestial sphere, and the relative relationship between the sun and the earth's equator is calculated by observing the relative position between the sun and the celestial equator. In this way, we can observe the winter solstice, the vernal equinox and the summer solstice.

Moon map, spring and autumn equinox, summer and winter solstice and Huang Chibai Road.

Therefore, the inclination angle between the earth's axis and the orbital plane is the intersection angle between the ecliptic and the celestial equator on the geocentric celestial sphere, also known as the intersection angle between the ecliptic and the Huang Chi distance. However, it is a great pity that only the mid-latitude areas can observe the phenomenon of "inclination" of the earth!

I feel a little sad that ancient astronomy in China was described by astrology, numerology and medicine. People often say that Chinese medicine is metaphysics and its theory is unpredictable, which is ignorance of China tradition.

However, few people know the knowledge of ancient astronomy today. At the end of the Ming Dynasty, Gu said, "Everyone knows astronomy for more than three generations. Fire in July' is a farmer's word; Samsung is in the sky', the language of women is also; The end of the month', the merits of guarding the pawn; The story of "The Long Tail Theory and Chen Fu" is also a rumor aimed at children. Later scholars learned the soil, and the questioner was at a loss. " ("Rizhilu" Volume 30). Because of this, many people in China can't understand the culture of China!

If you know the basic knowledge of ancient astronomy in China, you can learn a lot about China culture. Only by observing the celestial phenomena for a long time can we know that the ancients were not stupid, and understand the ancient concept of time and space, can we make such a sound of "harmony between man and nature"!

The starry sky, the sun and the moon are the only means for the ancients to understand the universe. At this point, there are many similarities between the East and the West. For example, there are zodiac signs in foreign countries, zodiac signs in China, sundials in China and sundials abroad. These similarities are too numerous to mention, and they all stem from the observation of the same objective phenomenon. However, it must be mentioned that when the west can combine the precise timing system obtained by developing machinery with the telescope obtained by developing glass (both machinery and glass are derived from the demand of the church to build the main church, bell tower and colored windows), it will lag behind the east in its understanding of celestial bodies.

References: 1. Tianwu and Xuan Ji, the ancient "harmony between man and nature" in China and the Japanese track (the zodiac); Observation range of ecliptic and equator

The ecliptic is invisible, just a theoretical virtual plane. Now let's use our imagination. First of all, we should know that the earth we live in is spherical, while the universe is vast and huge. Although the universe is limited, because the earth is too small in the universe, we can imagine the universe as boundless.

In this boundless universe, there are 10 trillion galaxies and trillions of stars. Our sun is just an ordinary star among these trillions of stars, and the earth is just a satellite planet of the sun, with a mass of about one third of that of the sun.

We can also imagine that with the earth as the center, the whole universe surrounds our earth, so we call the sphere around the earth a celestial sphere.

The earth is wrapped in this celestial sphere and rotates once a day around the sun and once a year. Thus, from the earth's point of view, it seems that the celestial sphere and the sun revolve around us. Every day, the celestial sphere rotates once and the sun rises in the east and sets in the west.

This is also the origin of ancient geocentric theory.

In a year, the sun moves on the big screen with the celestial sphere as the background, only once a year, from the position of a certain star to the position of a certain star. In this way, the sun rotates around the celestial sphere to form a surface, which cuts the celestial sphere in half. This surface is called the ecliptic plane.

In fact, the stars are constantly moving, but because they are too far away from us and the nearest stars are several light years away, their movement is very small compared with the distance to us. From this point of view, they seem to have changed very little, and have hardly changed for thousands of years. Ancient people thought they were eternal, so they called them stars.

In this way, humans can draw the ecliptic on the celestial sphere with the stars as the reference coordinates.

Simply put, we can draw a circle on paper with the sun in the middle and a small ball on the circle line. This small ball is the earth. This circle is the earth's orbit around the sun. Draw this circle with yellow pigment, and this yellow face is the ecliptic.

So you can see the ecliptic. We can also imagine the earth spinning like a football. This rotation has an imaginary axis of rotation, which runs through the north and south poles of the earth, and the rotation of the earth rotates around this axis.

Every rotating ball has a surface point, which produces the longest circumferential line as the ball rotates. The plane of the longest circumference of a perfect circular ball makes an angle of 90 degrees with the axis. The earth's rotation also has such a circle, which is called the equator. Because the rotation axis of the earth is not perpendicular to the ecliptic plane, it forms an included angle of 66 34' with the ecliptic plane, so the equator of the earth is not on the same plane, but has an included angle of 23 26'.

Don't underestimate this included angle. It is this angle that makes the position where the earth receives direct sunlight constantly change on the earth, forming the Tropic of Cancer, which leads to the alternation of cold and hot temperatures throughout the year, creating the necessary conditions for the birth and evolution of life.

The reason why the earth tilted its neck was because it collided with a planet the size of Mars at birth.

This is a long story, which is not discussed in this article. Let's stop here.

Welcome to the discussion, thank you for reading.

People on the earth look at the apparent path of the sun between stars in a year, that is, the great circle where the earth's orbital plane intersects the celestial sphere. The ecliptic and the celestial equator form an angle of 23 degrees and 26 minutes, and intersect at the vernal equinox and the equinox.

In the universe, the earth, as a planet in the solar system, is constantly moving, and its movement is complicated, but the most basic movement is the rotation and revolution of the earth. The rotation of the earth is that the earth itself rotates from west to east around its axis of rotation. The rotation axis of the earth, referred to as the earth axis. The axis of the earth is hypothetical, but when the earth rotates, it seems that this axis exists. The plane perpendicular to the earth axis through the center of the earth is called the equatorial plane, and the great circle intersecting the earth surface is called the equator. The equator divides the earth into two hemispheres. The axis of the earth passes through the center of the earth and intersects the surface of the earth at two points, of which the intersection in the northern hemisphere is called the North Pole and the intersection in the southern hemisphere is called the South Pole. The earth revolves around the sun from west to east while it rotates on its axis of rotation. The orbit of the earth is an ellipse close to a perfect circle. The plane formed by this ellipse is called the orbital plane, also called the ecliptic plane. As the earth revolves around the sun, it also rotates around its axis. In this process, the earth axis is not perpendicular to the orbital plane (ecliptic plane), but inclined with an included angle of 66 34'. However, the tilt direction of the earth's axis remains unchanged in space (translation), so the equatorial plane and the ecliptic plane are not coincident (not parallel) but inclined, and the included angle is the complementary angle of 66 34', that is, 23 26'. This included angle is called the yellow-red intersection angle. The inclination and inclination direction of the earth's axis remain unchanged, which also leads to the different inclination of the earth's axis to the sun, so that the direct point of the sun on the earth moves back and forth between 23 26' north latitude and 23 26' south latitude. The relocation period is one year. This causes the seasonal difference between the height of the sun at noon and the length of day and night around the earth, thus forming the four seasons.

There is no ecliptic in the world, and many people say it. So you can't see the ecliptic anywhere! No matter on the earth or the celestial sphere, it only appears in the mind, just like the auxiliary line for making geometric figures.

The ecliptic is an astronomical name invented by scientists for the convenience of research. It has no entity, just like the axis of rotation, celestial sphere and coordinate system. ...

First of all, what is the "ecliptic of the earth"? Simply put, the ecliptic is the orbital plane of the earth around the sun, and the equator of the earth is tilted by 23.5? The intersection of the equator and it is the vernal equinox and autumnal equinox. But based on the geocentric theory, it is the trajectory of the sun revolving around the earth, assuming that the earth is stationary.

The word ecliptic has existed since ancient times, and the earliest record is Historical Records of the Warring States Period. In the early years of the Eastern Han Dynasty, Liu Xiang also recorded that "the sun and the moon are in harmony with the ecliptic" in Wang Ji Lun. It seems that the ancients have long known that the ecliptic is the orbit of the sun above the earth.

How can we see the ecliptic? As mentioned earlier, the ecliptic is an imaginary plane of the sun's orbit, which is invisible to the naked eye. Since it is imaginary, you can only imagine it with your clever brain. If you have better hands-on ability, you can draw it with a piece of paper and a stroke.

Because the ecliptic is the trajectory of the sun, draw a sun first (many people don't draw the sun), which is easier to understand, then draw an earth beside it, and then draw an ellipse as the orbit of the earth's revolution. This orbit is connected with the sun into a disk-shaped plane, which is the ecliptic plane.

Is it simple? Liao Liao drew it in a few strokes. Of course, you must have simple astronomical knowledge first.

If the ecliptic is an existing entity, you can see it as long as the sun shines on the earth day and night.

The ecliptic plane is formed by the movement of the sun, so there will be ecliptic in the whole solar system, and all celestial bodies in the system will revolve around the sun in the orbit near this plane.

In the early days of the solar system, the sun just formed, dragging a huge disk nebula around. As time goes on, these nebulae gradually condense into planets under the action of universal gravitation, and they also revolve within the gravitational range of the sun. At the same time, due to centrifugal force, angular momentum and other forces, scattered nebulae and celestial bodies move farther and slowly the equatorial plane of the sun moves closer. Under the blowing of the solar wind, the lighter gaseous planets are blown far away, while the heavier terrestrial planets stay near the sun, so a galaxy is formed.

Then the earth, one of the eight planets, revolves around the sun, and its orbit around the sun is called the ecliptic plane. On earth, it is the orbit of the sun on the celestial sphere.

"Auspicious day in the ecliptic" is a ceremony that people living in farming times choose an auspicious day in order to do things smoothly in the twenty-four seasons of spring, summer, autumn and winter. Therefore, the journey to see the 24 solar terms is the "ecliptic". Everyone has different "auspicious days" in their hearts.

The equator is in balance with sunlight. Only when the ecliptic is inclined to the sun can there be four seasons in a year. When the sun sweeps the meridian, time will not change.

The ecliptic angle or ecliptic exists because the sun rotates around its center with the solar system. The earth is not only attracted by the sun (rotating to form the equatorial plane), but also by the center of the solar system (twisting the equatorial plane to form the ecliptic plane). Therefore, simply looking at the changes of the solar system, the sun and the earth, we can't see the ecliptic, but also look outside the solar system, and see the change of the angle of Polaris and the contrast between the angle of the sun and the earth.