What happens when the earth's orbit is circular?
What will happen if the earth's orbit is circular? We can find out on the internet that the earth's orbit refers to the earth's orbit around the sun, and the earth's orbit is elliptical. But many people will be curious, what will happen if the earth's orbit is round?
What will happen if the earth's orbit is circular? 1 why is the earth's revolution an elliptical orbit? What if it's a cycle?
Some people may think that in the process of the earth's revolution around the sun, it meets the sun for a while and meets the sun for a while, which leads to the four seasons on the earth, but this is not the case. You know, the earth can be divided into the northern hemisphere, and the seasons in the two hemispheres are opposite. For example, it is winter in the northern hemisphere and summer in the southern hemisphere, which is when the earth is closest to the sun.
In fact, the reason why the earth has four seasons is that the rotation axis of the earth forms an angle of about 66 degrees and 34 minutes with the orbital plane of the earth. This angle is called "oblique rotation", which makes the direct sunlight point on the earth's surface move back and forth regularly between the Tropic of Cancer and the Tropic of Cancer, thus causing periodic changes in the earth's surface temperature.
What would happen if the earth didn't "turn sideways"
If the earth is not "tilted", it means that the rotation axis of the earth is perpendicular to the orbital plane of the earth. In this case, the direct point of sunlight will be fixed in the equatorial region of the earth, and the temperature of all regions of the earth's surface will be fixed accordingly. The higher the latitude, the lower the temperature, and there will be no seasonal changes.
It is conceivable that plants that depend on seasonal changes on the earth will be hit hard. In addition, there will be no monsoon and monsoon currents on the earth, and the consequences are unbearable for human beings. However, this is not over yet. In fact, if such a thing really happens, the situation may be worse than expected.
If the earth does not "turn sideways", it may become a "big snowball"
Under the same amount of solar radiation, how much energy the earth's surface can get from the sun mainly depends on the surface albedo (that is, the percentage of solar radiation reflected back to space from the surface per unit area).
For different ground conditions, there will be great differences in surface reflectivity, among which the albedo of ice and snow is quite high, generally above 50%, and the albedo of very "clean" ice sheet can be as high as 90%.
The poles of the earth are covered with thick ice and snow. With the change of seasons, the ice and snow at the poles of the earth will also melt seasonally. Generally speaking, the amount of snow and ice will maintain a dynamic balance.
If the earth does not "turn sideways", many ice and snow at the poles of the earth that should have melted in summer will not melt again. Because the air in the earth's atmosphere is constantly flowing, when the air containing water flows to the poles of the earth, most of it will be fixed for a long time.
As this process continues, the amount of ice and snow at the poles of the earth will continue to increase. When it increases to a certain extent, the ice and snow at the poles of the earth will gradually spread to low latitudes.
In this case, there will be a positive feedback mechanism to make ice and snow spread, that is, ice and snow will reflect a lot of solar radiation back to space, which will lead to the temperature drop in its area, and the temperature drop will promote the formation of more ice and snow, and then reflect more solar radiation back to space. ...
In this way, the ice and snow layer spreading from the two poles of the earth will continue to be in a state of "development and growth", and its coverage will continue to increase and spread to low latitudes, eventually turning the earth into a "big snowball".
Of course, because the earth is not tilted, the area near the equator of the earth will directly receive strong solar radiation, and some areas may not be completely frozen, so the earth may look like the above picture.
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The theoretical basis of the above speculation comes from the Milankovitch Hypothesis put forward by Yugoslav scholar Milankovic.
In short, when Milankovic studied the relationship between the earth's orbit parameters (such as the eccentricity of the earth, precession of the orbit, inclination of the axis, etc.). ) and the earth's climate, he found that the inclination of the earth's rotation axis relative to the earth's orbital plane will change cyclically between 22 degrees and 24.5 degrees. When the inclination reaches the minimum, it may cause the phenomenon that "the snow in winter will not melt" on the earth, which is caused by the positive feedback mechanism mentioned earlier.
It is worth mentioning that Milankovitch hypothesis was put forward in 1920, but it was not recognized by the scientific community for a long time because of insufficient evidence.
Until the 1970s, with the help of modern science and technology, geologists obtained precious samples of the deep seabed and analyzed the data of marine climate changes in the past several hundred thousand years. The final research results show that the situation described by Milankovitch hypothesis is basically consistent with the past climate change cycle of the earth, and since then, the hypothesis has been gradually accepted by most people.
In short, it is better for the earth to "turn sideways" as it is now.
What if the earth's orbit is round? Suppose the earth's orbit around the sun is perfect. A perfect circle means that in this orbit, the earth rotates around the sun at exactly the same speed and the distance from the sun remains the same. Sure, this is no problem. After all, this shape of a circle is defined like this.
It's just a physical requirement To run on this circular orbit, dynamic balance must be satisfied. In other words, the gravity of the earth by the sun is exactly the same as the "centrifugal force" produced by the earth's circular motion around the sun. Of course, assuming a perfect circular orbit, these two forces are obviously equal and there is no problem. But remember, the gravity is related to the distance between the earth and the sun. The magnitude of centrifugal force is not only related to the distance, but also related to the speed at which the earth moves around the sun.
The specific formula does not need to be particularly clear, just a general concept. There are not only the sun and the earth in the solar system, but also many other celestial bodies. This photo is now a map of the inner planets of the solar system orbit. Except for Mercury, True Star, Earth and Mars, all the lines are known orbits of near-earth asteroids. Doesn't it look dense?
In this environment, it is only a matter of time before it orbits the sun and collides with a near-earth asteroid. No matter how big the asteroid is, if it hits the earth, the speed of the earth will definitely change. Remember that speed is related to centrifugal force? After the collision, the speed of the earth is slightly accelerated, the centrifugal force will increase, and the distance from the sun will begin to increase. On the contrary, if the speed of the earth slows down after the collision, the distance between the earth and the sun will begin to decrease.
In both cases, the earth will no longer be able to move along the "perfect circle" orbit originally assumed. Fortunately, there is a way to achieve a dynamic balance between centrifugal force and gravity, so that the earth can continue to move around the sun in an imperfect circular orbit without colliding or falling on the sun. This orbit is an ellipse.
Has the earth been hit like this? Ask the dinosaurs 65 million years ago, or look up at the uneven moon, and you will get a definite answer. Collision is just an extreme example. Even if there is no direct collision, other celestial bodies can change the running speed of the earth through the remote action of gravity. Therefore, even if the earth's orbit used to be a perfect circle, it can't be maintained today, and it has become an ellipse due to various factors. What's more, the circle is just a special form of ellipse, and the earth's orbit around the sun may not be round at first.
What will happen if the earth's orbit is circular? What will happen if the earth stops turning?
British novelist Wells once described a story: haunters George always does good deeds in secret at night. In order to prolong the time of doing good, he simply stopped the rotation of the earth, but it turned out to be a disaster.
According to Neil Cummins, an astrophysicist at the University of Maine in the United States, the significance of such fantasy stories lies not only in entertainment, but also in helping people to understand the laws of the real world more clearly. In his new book, Comins considers what the world around us will look like in several strange scenes, such as the earth stopping spinning.
It is reported that it is easy to think that we are standing on the ground and the earth is in a "static" state. After all, we can't feel any movement in the surrounding environment, but when you observe the sky, you will get evidence that the earth is moving.
Some of the earliest astronomers suggested that we live in a universe centered on the earth, which means that the earth is the center of everything. They say that the sun revolves around our earth, leading to sunrise and sunset, and so do the movements of the moon and planets, but the actual situation does not conform to this vision.
Sometimes, a planet will go backwards in the sky before it can move forward again. We call this kind of motion "reverse motion", which occurs when the earth "catches up" with another planet in orbit. For example, the orbit of Mars is farther from the sun than that of the Earth. In the respective orbits of the Earth and Mars, we "catch up" with Mars and then stay away from it.
When we reach the near fire point, Mars will "run backward", and then when the earth gradually moves away from Mars, Mars will run forward. Another evidence about the center of the sun comes from parallax observation, or obvious changes in the position of stars relative to other planets.
When we observe the starry sky on the earth, the earth has been running around the sun for 365 days. If we observe a star in summer and observe it again in winter, you will find that their positions in the sky change obviously, because our positions in orbit are different. We observe the stars from different vantage points, and then through some simple calculations, we can also use parallax to calculate the distance to the stars.
How fast does the earth go around the sun?
Of course, the rotation of the earth is not the only way for us to move in space. According to the data of Cornell University, the speed of the earth around the sun is about 107000 km/h, which can be calculated by basic geometric formula.
First of all, calculate the running distance of the earth. It takes 365 days for the earth to go around the sun. This track is oval. To simplify the calculation, the orbit is regarded as a circle. According to the data of the International Federation of Astronomers, the orbit of the earth is the circumference of a circle, and the distance from the earth to the sun is called an astronomical unit-149597870 kilometers, which is the radius distance (r), and the circumference of a circle is equal to 2×π×r, so the annual travel distance of the earth is about 940 million kilometers.
Because the revolution speed of the earth is equivalent to the distance traveled in a certain time range, the earth walks 940 million kilometers in an average of 36.525 days, and the result divided by 24 hours is the running speed per hour. The results show that the earth runs 2.6 million kilometers every day on average, that is, every hour 107226 kilometers.
How fast does the earth rotate?
The rotation speed of the earth is constant, but the rotation speed depends on your latitude. For example, according to NASA, the circumference of the largest part of the earth is about 40070 kilometers, also known as the equator. A day is 24 hours. Divide the equatorial circumference by 24 hours a day, and the result is that the rotation speed at the equatorial position is 1, 670 km/h.
But it doesn't move fast at other latitudes. If we move to the latitude of 45 degrees (south latitude or north latitude), we can use the cosine value of latitude to calculate the rotation speed of the earth. A good scientific calculation method should have cosine function, and the cosine value at 45 degrees latitude is 0.707, so the rotation speed at this position is about 0.707×1037 =1180 km/h, and the further south or north, the rotation speed of the earth will gradually slow down.
Space agencies like to use the rotation speed of the earth. If they send humans to the International Space Station, for example, the best launch site is near the equator, which is why NASA usually chooses to launch goods to the International Space Station in Florida, which is in the same direction as the earth's rotation, which will help the rocket fly faster.
The sun and galaxies are also moving.
The sun has its own orbit in the galaxy. The sun is about 25,000 light years away from the center of the Milky Way, and the diameter of the Milky Way is at least 654.38+ million light years. According to the data of Stanford University, the earth should be in the middle of the center of the Milky Way, and the sun and solar system run at a speed of 200 kilometers per second, or the average speed is 720,000 kilometers per hour. Even at this speed, it will take about 230 million years for the solar system to circle the center of the Milky Way.
At the same time, the Milky Way moves in the universe relative to other galaxies. About 4 billion years later, the Milky Way will collide with the neighboring Andromeda galaxy. They rushed at each other at a speed of 1 12 kilometers per second. So all the celestial bodies in the universe are moving.
What will happen if the earth stops spinning?
With the movement of the earth, you can't be thrown directly into the air, because the gravity of the earth is very strong, much stronger than the rotation of the earth. The latter sport is called centripetal acceleration. On the equator, the strongest point in the centripetal acceleration, centripetal acceleration can only offset 0.3% of the earth's gravity. In other words, you don't even notice that people in centripetal acceleration weigh less at the equator than at the poles.
NASA said that in the next few billion years, the possibility that the earth will stop rotating is "almost zero". However, in theory, if the earth suddenly stops running, it will have a terrible impact. The earth's atmosphere will still run at the original rotation speed of the earth, which means that all objects on the land have been removed, including humans, buildings, trees, topsoil and rocks.
What if this process is more gradual? Nasa pointed out that this is the most likely situation in billions of years, because the sun and the moon are pushing the earth to rotate. This will give humans, animals and plants enough time to adapt to this change.
According to the laws of physics, the slowest rotation speed of the earth in the future is 365 days. This situation is called "sun synchronization", which will force one side of the earth to face the sun all the time and the other side to face the sun permanently. In contrast, the moon has been rotating synchronously with the earth, with one side of the moon always facing the earth and the other side facing away from the earth.
Nasa said that if the earth stops rotating completely, there will be some strange phenomena: the earth's magnetic field may disappear because the magnetic field is partially generated by rotation; We will no longer see colorful auroras, and the Van Allen radiation belt around the earth may disappear;
The earth will be completely exposed to solar radiation. Whenever the sun releases coronal mass ejections (charged particles) to the earth, these substances will hit the earth, and all substances on the earth will be immersed in radiation, causing serious harm to life on the earth.
Although it is impossible for the earth to stop in a few short decades in reality, the rotation speed of the earth is indeed slowing down. After several billion years, the rotation of the earth will be synchronized with the revolution. Wells's science fiction "The Time Machine" also depicts the eternal sunset scene on the earth at this time. But apart from fantasy, such a distant future is unpredictable.