Here's what I think of Pluto] Video this week . I assume that Bridenstine was just kidding because someone in the background is laughing and I think I see a grin on his face. But now is a good time to discuss the complicated question of Pluto's Planethood.
Pluto is a planet. Pluto is not a planet either. The word "planet" is indeed an obsolete concept that does not capture the complexity of the universe.
A planet originally referred to everything that traveled across the sky, including the comets, the sun and the moon . , As scientists looked more closely at the objects in the sky, they found that the Earth orbited the Sun and that the other objects in the Solar System could be further sorted. Planet has earned the definition "you know if you see one" – Mercury, Venus, Earth, Jupiter, Saturn, Uranus and Neptune are obviously planets. The moon would not be a planet because it is a moon. Since then, we have attached importance to this planet and have identified ourselves with it.
When Clyde Tombaugh discovered Pluto in 1930, he saw a stain that traveled across the sky. By definition, he was looking at a planet.
But in general, the more you query a category, the less defined it is. In 1992, scientists David Jewitt and Jane Luu discovered an object called Albion in the then-theorized Kuiper Belt beyond Neptune. Later, Eris, Makemake, Haumea, and researchers soon discovered that there were a number of Pluto-like objects in the outer solar system. Eris was especially problematic because it is more massive than Pluto. The question was: are we going to turn these big Kuiper belt objects into planets or are we going to degrade Pluto?
In 2006, the International Astronomical Union opted for the second option, defining an unsatisfactory set of criteria for a planet. Planets must be round because of their own gravity, they must circle the sun, and they must "clean up their neighborhood," a fairly unscientific term that basically means they are the dominant gravitational body in orbit. Pluto and Eris were called "dwarf planet" because they did not "clear" their neighborhood. That makes sense somehow. If you look at Pluto and Kuiper Belt Object Charon together, you will notice that Charon Pluto is not orbiting. the two circle a point between them.
Since then, it has been difficult for humans to accept the loss of Pluto's Planethood – which makes sense because we love our planets. In addition, NASA's very expensive New Horizons mission to Pluto was launched in 2006. Visiting a dwarf planet when you thought you were visiting a planet is akin to explaining scientists that another mountain on the way to Mount Everest is the highest mountain. Two years ago, scientists, including New Horizon's Principal Investigator and Pluto Evangelist Alan Stern, proposed making every round object a planet smaller than a star. Incidentally, this definition does not work because there are many objects that span the boundary between star and planet.
This debate is not objective. Today, the word is most important for astrologers, nostalgic people, as well as for universities and agencies such as NASA, whose funding depends on the definition of the word . Neither Pluto nor the rest of the objects in the solar system nor the laws of physics have heard of Jim Bridenstine or NASA or Alan Stern or other humans.
Without a doubt, Pluto fits in with the old definition of planets. But as we learn more about planets, we've found that it just does not belong to the same category as the other eight things we call "planets." The problem is not with Pluto. The problem is that we put too much emphasis on the dated term and the language did not develop as fast as our understanding of the universe. But in reality it's one of many big, round and interesting ice masses beyond Neptune … and that's it. The reality does not fit satisfactorily in our semantic compartments.