When we were children and were taught which planets belonged to the solar system, Pluto was always the last on the list. However, over the years, this planet was removed from the list for various reasons. Many people don't know what happened to Pluto and why it is no longer considered a planet in the solar system.
In this article we are going to tell you what happened to Pluto, what characteristics a celestial object must have to be considered a planet and much more.
What happened to Pluto
In August 2006, Pluto's status as the ninth planet of the Solar System was changed, and it was reclassified as a dwarf planet. This decision was made by the International Astronomical Union (IAU), which stated that a celestial body must meet three specific conditions to be considered a planet . These conditions include orbiting the Sun, possessing a mass large enough to create a spherical shape due to gravitational forces, and having a clear neighborhood of other objects.
After a vote carried out by the international community of astronomers, Pluto was excluded from the definition of a planet because it shares its orbit with other celestial bodies. As a result, our Solar System is now officially composed of eight planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune), each with their own satellites, five dwarf planets (including Ceres, Haumea, Eris, Makemake and Pluto), as well as asteroids, comets, interstellar gas and dust.
Gloria Delgado Inglada commented fifteen years after Pluto's reclassification, stating that the ensuing controversy over whether to demote Pluto or reinstate its planetary status was a positive thing. She believes the debate allowed for a deeper understanding of the issue and provided an opportunity to learn from a variety of perspectives.
During an episode of the Radio UNAM program Primer Movimiento, it was stated that the debate over whether there are eight or nine planets is not the ultimate concern. Rather, it is imperative to make consistent observations and definitions. As additional evidence, new theories, and advanced tools are acquired, the definitions of concepts will develop and become more precise. Furthermore, to delve deeper into this topic, you can consult the article on why Pluto is not a planet or read about Pluto's atmosphere.
Considerations in antiquity
In ancient times, both the Sun and the Moon were classified as planets. The head of the Science Communication and Culture unit at the IA recalled that in the 2nd century AD, the geocentric or Ptolemaic model of the universe was widely accepted. This model considered the Moon and the Sun to be planets that revolved around the Earth, which was believed to be the center of the entire Solar System.
In the XNUMXth century, Nicholas Copernicus challenged the prevailing idea that the Earth was stationary and proposed a new model. According to his heliocentric model, the Earth rotated on its own axis and at the same time rotated around the Sun. This model has endured to this day and remains the guiding principle.
Recently, newly discovered celestial objects and Ceres, the first dwarf planet, have garnered much attention. During the quest to discover new astronomical bodies, William Herschel stumbled upon Uranus in 1781. In 1846, by using mathematical predictions, Urbain Le Verrier and Johnan Galle were able to locate Neptune.
By 1801, astronomers had already identified Ceres, a sizable object that was the only one known to exist in the asteroid belt between Mars and Jupiter at that time. Initially classified as a planet, it was reclassified as an asteroid when more similar objects were discovered. However, it is worth noting that Ceres still accounts for a significant third of the total mass in the asteroid belt.
According to the speaker, the asteroid belt has a total mass equivalent to 4% of the mass of our Moon . Experts have identified Ceres as the final step in the process of becoming a planet. Furthermore, Ceres' classification was revised even before Pluto was discovered, making it a pioneer in its category.
In 1930, Clyde Tombaugh, a renowned astronomer, managed to discover Pluto. Prior to this discovery, Percival Lowell, one of Tombaugh's colleagues, had been on a mission to locate the planet since 1905. However, it was later discovered that Pluto's mass had no impact on the orbits of Neptune and Uranus. , thus denying Lowell's claim.
He stated that the advancement of science is not simply the result of successes, but also the consequence of errors, miscalculations, or a lack of conclusive results . This is important because it allows us to broaden our understanding, which is the very goal of science.
After much deliberation, he concluded that science is constantly evolving to accommodate new data and theories. In fact, some astronomers have postulated that the definition of a planet has changed over time, raising the possibility of future revisions and votes that could alter our understanding of these celestial bodies. If you'd like to learn more about Pluto's current status, you can read about interesting facts about Pluto or about Pluto's classification as a dwarf planet.
Characteristics to be considered a planet
The definition of a planet has been debated throughout history, but currently, certain specific criteria are followed to classify a celestial body as a planet. These criteria were established by the International Astronomical Union (IAU) in 2006 and are known as "The Pluto Resolution."
- Orbit around the sun: The first fundamental requirement is that the object must orbit the Sun. This means that objects that orbit other stars will not be considered planets.
- Enough mass to have a spherical shape: A planet must be large enough that its own gravity allows it to take on a spherical shape. This is important to distinguish them from asteroids and other celestial bodies that may have irregular shapes.
- Having cleared its orbit: A planet must have cleared its orbit of other objects, meaning that its gravity has cleared the surrounding region of any significant material. This differentiates it from "dwarf planets" that have not managed to clear their orbit, such as Pluto.
These three criteria are essential for an object to be considered a planet in our solar system. However, it is important to note that these criteria apply specifically to the planets in our solar system. Other star systems may have their own classification criteria.
The Pluto Resolution, which excluded Pluto from the category of planet, generated some controversy at the time, but it was based on the need to establish clear and consistent definitions for the classification of celestial objects. Since then, Pluto has been considered a "dwarf planet" rather than a planet because it has not cleared its orbit of other objects. For more information on the various dwarf planets in our solar system , feel free to consult the corresponding article.
I hope that with this information you can learn more about what happened to Pluto.