When I was a kid, there were nine planets.
Now we know thousands of people! However, it includes the world of an alien that goes around the expornet and alien sun. Only eight planets are called our hometown. Or, if some astronomers are right, there may still be nine people who have passed Neptune. On the other hand, if you are nostalgic (and a little confession), there are still nine, but you need to include so -called dwarf planets to make fairness. Only the sun will go around.
The planet is messed up. Or, perhaps more important, our way of thinking about them is.
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“What is a planet?” It looks like a simple question, but it’s nothing.
You can go in the ancient sense of words. planet It means an ancient Greek word “Wanderer”, which refers to the fact that the planet and the earth go around the sun, and the point of the sky seems to be moving compared to the stars in the background. In this sense, the sun and the moon are also included. Most people agree is not a planet. It also contains comets and asteroids, but now you can see that this may be too broad definition.
Probably a more modern take is required. However, it is also troubled by trouble.
In the early 2000s, the term “planet” was not so discussed. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pru Royal all claimed Monica. However, some troublesome astronomers had to shake things by discovering Sedona, Quaoar, and Eris. These are ice and rock bodies that go around the sun after a considerable amount of Neptune and PL Royal, and the width is over 1,000 kilometers. In fact, the width is 2,300 km or more, and Ellis is comparable to UT Royal, and is somewhat large. So are these also planets?
When Ellis was announced in 2005, one of the discoverers, astronomer Mike Brown, even called the 10th planet in the NASA press material. At that time, it was thought to be slightly larger than UT Royal. And if we call the PL royal planet, Ellis is also worthy. Even if the better observation results were slightly downgraded Eris into subplute, the problem remained. How many planets are in the solar system?
With the growing confusion, the International Astronomical Union (a global group of astronomers, an official keeper of the universe naming law), causes IAU to create a search committee to propose potential definitions. I did it. Several suggestions were suggested, but most of them were inadequate. For example, there was a proposal that would include Ceres, the largest asteroid of the main asteroid belt between Mars and Jupiter as planets. But it is smaller than what most people think is a planet. Many planetary scientists are currently believing CERES is a protoplanet. I believe that this is a large object that is approaching the height of the planet in the early days of the solar system, but grew up with the material.
Eventually, in 2006, IAU settled on the definition of three parts. The planet is huge enough to go around the sun and become a round shape due to gravity, and “clearing the neighborhood around the orbit” means the most gravity. Domestic body there. (This term was misunderstood that the planet could completely clean all the other bodies, so it caused confusion at first. This is impossible.) If you do not meet the two conditions, if you meet the third condition, that’s it. It is called the “WAR star” planet.
This means that PL royales are not considered as major planets like mercury or earth, but are considered as planets for dwarfs. Some astronomers did not like this definition because of the declining PL royal status. And certainly, even today, I am dissatisfied with the voice of the PL royal demotation.
Other definitions have been proposed for many years and are better than other definitions. In my opinion, one seemed to be defined in the backward just to include the PL royal. But frankly, such a reverse engineering is a method that has reached the current 8 Planet situation. If you want to say that Uto is a planet, you need to include Ellis at least. After setting a specific preceding example, Many The planet of other D stars. Without a solid size or mass, you have to say that there are hundreds of planets in the solar system. Objects must be rounded through self -gravity, at least about 400 km, but there are still a lot of space that has not been found in the darkness beyond Neptune.
Now we have no scientific reason you can’t There are thousands of planets in the solar system, culture Consideration is another problem. Most space scientists stand in eight or nine, as excess planet seems to dilute the term itself.
Or do you need to be “9 or 10”? Astronomers are now pursuing this idea. Many small outer solar -based objects seem to have tracks arranged in a specific mysterious way. The simplest explanation is that those movements are still affected by the body of non -scenes, which are more than 30 km from the sun and are many times the mass of orbitals. The potential position of the world in the sky, which is temporarily called a planet Nine (and voice), is not clear. Various teams of astronomers propose different hidden places on planet 9. The appearance of large -scale telescopes such as Vera Rubin Observatory is set to greatly narrow down the search or find the charged planet. If you find it, it’s up to you, whether you want to call it the ninth or tenth planet.
But be careful before you make a decision. The main reason we struggled to come up with the definition of a planet for a long time is That’s not clear。 As Brown put in a book in 2010 How to kill the PL Royal and why it came,, “Planet” is a concept rather than a definition, and is common. He is right. There are no hard and fast lines that can draw the concept of planetary to draw the concept of planets and distinguish them from other class objects. Regardless of whether the overall or part is determined by mass, size, shape, orbital, or at first glance, Planethood standards seem relentlessly arbitrary.
Such slide is a universal theme of natural science. The definition is a human dull, not a natural event. Look at the color. The wavelength cut -off defines orange and red reductions, but the boundaries are selected and are not observed. Blue light and red light are two flavors of the same thing, with different wavelengths. And all colors in between are literally along the spectrum. The next step is blended with the next step without a sharp step to identify them.
It is not difficult to come up with more examples, such as gender, gender, political affiliation, and species. All of these exist in the spectrum. The difference is clear between the examples of both ends of the spectrum, and they are tempted to put them in binaryika Tegori, but the difference is much more difficult to bully when comparing two samples nearby. So where do you draw a line?
Humans like to put things in a clear category, but in general, nature is not so noisy. It acknowledges that it will make life easier and help us to understand the universe and ourselves.
