Terrible Pluto: It is not unfair to be kicked out of the ranks of planets in the solar system

Humans love to give names to celestial bodies, and these names often live up to their names. Take Pluto, for example. The name sounds a bit unlucky, so it's no wonder that people find it scary and unlucky.

The terrifying and mysterious Pluto

So, how terrible is Pluto? Why is it not unfair to kick it out of the ranks of planets? Next, let's take a closer look at the world of Pluto and see what happened.

The former "Nine Planets" family

Discovery of Pluto

Pluto, a dwarf planet outside the solar system, was discovered relatively late, but astronomers had already "predicted" it before it was officially discovered.

Before this, people had successfully discovered the position of Neptune by analyzing the orbital disturbances of Uranus. Therefore, at the beginning of the last century, American astronomer Percival Lowell reused this method and built an observatory specifically to search for mysterious celestial bodies that affect the orbit of Neptune.

In his opinion, the gravitational force of this celestial body caused Neptune to change its expected orbit. And the mysterious celestial body in this prediction was Pluto.

Lowell Observatory, funded by Percival Lowell

Later, young Clyde Tombaugh arrived at the observatory and began his work. He needed to compare numerous negatives and find out the celestial bodies that had moved.

You know, there are hundreds of thousands of stars in each film, which means that the comparison work is very difficult.

However, Tombaugh was very patient. He used a "flash comparator" to compare the film negatives and finally discovered Pluto on February 18, 1930.

The arrow points to Pluto.

This celestial body in a distant place appeared in people's field of vision and was treated as the ninth planet.

It is worth mentioning that due to the great distance between them, even if Pluto was confirmed to exist at that time, it was just a "bright spot" on the film, and people knew very little about it.

With the advancement of observation technology, people gradually realized how "terrible" Pluto is.

Pluto gradually loses its mystery

The "terrible" Pluto

First, let's get to know some basic information about Pluto. Pluto's name is Pluto, the god of the underworld in Roman mythology, which corresponds to Hades in Greek mythology. Its main components are rock and ice, and its mass is very small, only one-sixth of the moon's.

Pluto's size compared to Earth

Because of its great distance from the sun, Pluto's orbital period is 247.94 years, which means that since it was discovered in the last century, it has not yet completed a complete orbit around the sun.

In addition, this distance means that Pluto receives very little heat, so its surface temperature is extremely low, around minus 229 degrees Celsius.

Judging from the above, Pluto does not seem to be scary or weird, so why do astronomers think it is a "freak celestial body"?

Sputnik Ice Sheet on Pluto

The first point is Pluto's satellites. Although this guy is not big, it has five natural satellites, and the most bizarre one is Charon. In order to make its name match Pluto, scientists named it after the ferryman of the Styx, Charon.

The strange thing about Charon is that its average radius reaches 606 kilometers, which means that its diameter is half of Pluto. Not only that, its mass is 12% of Pluto. Although this value is still far behind, it is already the satellite with the smallest size difference with its parent star in the solar system, and the two have also achieved "tidal locking".

Because of this, for a long time, scientists regarded it as Pluto's twin brother.

Charon and Pluto as seen by the New Horizons probe

The second point is Pluto's magical orbit.

From the picture we can see that its orbit is a very flat ellipse. This makes the difference between its perihelion and aphelion very large, about 4.5 billion kilometers from the sun when it is closest, and 7.4 billion kilometers when it is farthest.

The elliptical orbit is obviously different from that of other planets.

Looking at its orbit alone, you can only see that it is a bit flat, but if you compare it horizontally with the orbits of other planets in the solar system, you can find that this guy is indeed a "freak".

Because the angle between its orbit and the solar equatorial plane reaches 17 degrees, this special feature makes people suspect that it was not formed in the same "system" as the other planets.

Pluto's very exaggerated "three-dimensional" orbit

As for the scary thing about Pluto, it mainly refers to its surface environment. On the surface, everyone just thinks it's a little cold, but in fact, Pluto is a little cold. The low temperature of minus 220 degrees Celsius is like a natural refrigerator, freezing the possibility of life birth and survival.

Secondly, although there is a thin atmosphere on the surface of Pluto, its atmosphere is rich in nitrogen, carbon monoxide, methane, etc. This means that if you go to Pluto and take a deep breath here, you will most likely be poisoned and die immediately.

Pluto's icy mountains, ice sheets, and haze layers

Finally, let's talk about the topography of Pluto's surface. According to current observations, the surface of Pluto, an ice planet, is not as smooth as the ice rink that everyone expects. On the contrary, it is full of potholes, and people can easily fall into ice holes if they are not careful.

In addition, from the photos of Pluto, we can see that there are dark red areas on its surface, which means that its topography is more complex than we imagined.

The mysterious and colorful Pluto

In summary, Pluto is indeed one of the most bizarre celestial bodies in the solar system. And a major event has happened to it, which is the familiar "downgrading" event.

So why was Pluto demoted? And what impact did its demotion have?

Pluto Demoted

Many people have the impression that there are nine planets in the solar system. This is not because they remember it wrongly, but because it was indeed the case in the past. Since Pluto was discovered in the last century, it has been treated as a planet and successfully became the ninth planet in the solar system.

However, this title is not "awarded for life" because as astronomers discovered the unusual characteristics of Charon and discovered more small celestial bodies in the Kuiper belt, they pointed out that Pluto should not be called a planet.

Schematic diagram of Iber belt objects and satellites

Because it is about the same size as Makemake, Eris and others, if it can be defined as a planet, then those celestial bodies undoubtedly have a chance as well.

In addition, we have mentioned above that Pluto's orbit is also quite different from the other eight planets. Under the combined effect of the above conditions, many astronomers believe that Pluto's position in the solar system should be redefined.

"Solar System Family"

The controversy surrounding it eventually escalated to the International Astronomical Union, which even set up a special committee on the definition of a planet.

Later, after long discussions and consultations, the International Astronomical Union made a new definition of the planets in the solar system, and these new definitions can be said to be piercing the heart of "Pluto" with every word.

A new definition was adopted in August 2006: a "planet" must meet three conditions: first, it must be located in an orbit around the sun; second, its mass must be large enough to overcome the gravity of solid objects and achieve a shape of hydrostatic equilibrium; and third, the area near the orbit must be cleared, and there must be no celestial body larger than it within the range of its orbit.

Pluto is not qualified

In this case, Pluto was removed from the ranks of planets and became a "dwarf planet".

Although there are many controversies about the downgrade, most scientists believe that Pluto is not wronged because it does not have the qualifications to become a planet. As for why humans once worshipped it as a planet, it was because of limited observation conditions, which led to many misunderstandings about its mass for a long time.

Pluto joins the ranks of dwarf planets in the solar system

Therefore, since 2006, Pluto is no longer a planet, and has been numbered like an asteroid, with the number 134340.

I believe that if the solar system planet family had an internal meeting, Pluto would have become the ridiculed "clown" from then on.

Pluto is "excluded"

However, the "cold-blooded" earthlings don't care about this. On the contrary, everyone thinks that Pluto's demotion is still a historic moment, which marks that humans have improved their understanding of the universe. In the future, we may update more definitions because we see more and more things.

Professor Diamond of the University of Manchester in the UK said: "The new definition of a planet is very appropriate; we are likely to find more objects larger than Pluto in the solar system, and the new resolution standardizes the categories of these objects."

There are still many mysterious celestial bodies in the universe waiting for us to explore

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