Mankind has never stopped looking up at the starry sky in history. In the face of the vastness of the universe, our face is constantly expanding, and many cognitions have evolved from calculation, speculation, and observation to empirical or negation.
The book "The Rise and Fall of Pluto" written by American astronomer Neil DeGrass Tyson is a complete record of this story about Pluto. From questioning Pluto's status, to widespread discussion throughout society, to-for-tat speeches and debates by astronomers....You'll hear not only about Pluto's life, but also about the unique way of thinking in astronomy.
The story of Pluto begins at the beginning of the last century. At that time, it was already known that there were eight large planets in the solar system, which were arranged according to their distance from the Sun, from near to far, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
At that time, less than 100 years after the French astronomer Lévier discovered Neptune, the farthest point away, astronomers were still immersed in the passion for discovering new large planets.
At the same time, inspired by the discovery of Neptune, it was discovered that according to Newton's law of universal gravitation, Neptune's orbit was also abnormal. This means that there is a good chance that there must be another planet interfering with Neptune's movements.
In 1930, Tombaugh, a young man from the Lowell Observatory in the United States, observed the night sky alone for many nights, photographed and recorded repeatedly, and finally found the spider silk "star" trace that was later named Pluto in the dense 5 light spots on the **. Tombau was 24 years old that year.
Since the discovery of Pluto, astronomers have been estimating Pluto's mass since 1930 to verify whether its mass is large enough for a large planet, and the result is that Pluto's mass is less than 1% of Earth's. Could such a small planet cause definite interference with Neptune's orbit? The rigorous thinking of astronomers laid the groundwork for the ups and downs of Pluto's fortunes.
In August 1992, astronomers discovered another celestial body beyond Neptune's orbit, more than 100 kilometers in diameter. Such a discovery confirmed the previous conjecture of astronomer Kuiper that there are a large number of meteorites at the edge of the solar system. Astronomers speculate that Pluto may also be an asteroid in that region.
The fatal blow to Pluto was the discovery in 2005 of Eris, which also belongs to the Kuiper Belt and is more massive than Pluto. As a result of the discovery of Edi, Pluto not only lost its status as an independent possessor of space outside of Neptune, but also further lost its status as the largest celestial body outside of Neptune. The discovery caused an uproar in the astronomical community over the status of Pluto.
The consensus in astronomy at the time was that there had to be a definitive conclusion on the question of Pluto's position.
In 2006, the astronomical community welcomed the 26th Congress of the International Astronomical Union, which was held in Prague, the capital of the Czech Republic. The General Assembly of the Astronomical Union set up an important part of the discussion, which was discussed by astronomers from all over the world, and then voted on the draft. There were 2,500 astronomers at the conference, and more than 400 astronomers participated in the final day of discussion and voting.
After a week of discussions, the meeting finally came to the conclusion that in order to be called a planet, three conditions must be met: first, it moves around the sun. Pluto is fine with this one. Second, the mass is large enough to give itself a spherical shape. Pluto is no problem with this one. Third, it empties its own orbit, which means that it must be the main celestial body in this orbit, and there can be no other stars about its size. This is exactly what happened, and all kinds of facts proved that Pluto is not capable of dominating this orbit on its own.
Because Pluto does not meet this third criterion, the resolution stipulates that a new classification be created called dwarf planets, dwarf is dwarf, and all celestial bodies that do not meet the third condition are classified into this category, including Pluto and the aforementioned Eris.
In this way, Pluto was ruthlessly kicked out of the list of the great planets of the solar system by science! From astronomers, to localities, to ordinary people, there have been ups and downs of Pluto's downgrade. More than a decade later, the dispute continues.
Although Pluto has been downgraded, scientists have never stopped studying it.
In the summer of 2015, the New Horizons probe, launched by the Americans to explore Pluto, approached Pluto after more than nine years of flight. Because New Horizons was moving so fast, the man-made probe could only make a brief encounter with Pluto. In just 30 minutes, New Horizons explored Pluto in a variety of ways, photographing the clearest Pluto**, discovering the geological structure on Pluto, accurately measuring its volume and mass, and discovering more new moons of Pluto. If Pluto had not been positioned on the ninth planet, such exploration and discovery would not have been possible.
Scientific exploration is never-ending and tortuous, and what is needed is to respect the labor of predecessors, respect the scientific spirit, and perseverance.