Kindergarten in 2005 and Kindergarten in 2006 learned very different facts about the number of planets in the solar system. 2006, of course, was the year Pluto was reclassified as a dwarf planet — a move that sparked outrage among a public inclined to romanticize our solar system.
But long before Pluto was “controversial,” other bodies had moved in and out of the solar system’s official list of planets. In fact, kindergarteners in the early 19th century had taught that Ceres was a planet.
So, while the Earth debate may seem like a modern astronomical debate, 19th-century astronomers spoiled this question of how to determine what actually counts as a planet.
As it is hinted, Ceres is ahead of Pluto in its argument. The asteroid belt, located roughly between Mars and Jupiter, is full of minor planets and asteroids. One of those celestial bodies, Ceres, has a surface covered in minerals such as clay and carbonates, as well as water ice. It’s a strange world, for sure: Because it’s not completely frozen and covered in salt water, scientists think Ceres could harbor microbial life. This place Ceres is in stark contrast to Pluto, which is on the opposite side of the Solar System and has a completely frozen surface. Additionally, while Ceres is a dull gray monochromatic, Pluto’s colors range from white and black to bright orange.
However, Ceres and Pluto have one thing in common: astronomers at one point thought they should be classified as planets, but then changed their minds. It’s all about size, which is really important in the case of planetary science.
Flashback to the beginning of the nineteenth century. An Italian priest and astronomer named Giuseppe Piazzi at the Palermo Observatory answered a question nearly three decades old: Why do the orbits of Mars and Jupiter indicate a planet in between, even though neither has been found? On January 1, 1801, Piazzi seemed to answer this question by announcing that he had found a “star” that had moved from its position in the constellation Taurus. Scientists soon concluded that this was the lost planet and assumed that the matter had been resolved.
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Then another “planet” was discovered. On March 28, 1802, German physician and astronomer Heinrich Olbers Pallas discovered it. This was quickly followed by Juno in 1804 and Vesta in 1807. Both were duly classified as planets, although astronomers began to suspect that this increasingly cumbersome system was at work. Although scientists had a break for a few decades, a large number of new discoveries between 1845 and 1852 left the astronomical community with 15th asteroids to calculate. None of the new planets were classified as planets, but it was becoming increasingly clear that repairs would be necessary. By 1867, it was clear that Ceres was too small to be grouped with a body like Earth, and so it was given a new designation: small planet. Rather than being given fancy names and symbols, they will be tagged with numbers based on when they were discovered or their orbit determined.
This brings us to Pluto. While Ceres is 588 miles in diameter (compared to Earth’s diameter of 7,918 miles), Pluto is a relative 1,477 miles in diameter. However, this did not save Pluto from getting the ax as a planet when the International Astronomical Union met in 2006. The reason, quite simply, is that astronomers decided that there Three criteria To consider it a planet:
Therefore, the three IAU standards for a full-sized planet are:
It revolves around the sun.
It has enough mass to withstand hydrostatic balance (almost round shape).
It has “cleared the neighborhood” around its orbit.
Because Pluto did not meet the third condition – it did not “clear the neighborhood” around its orbit – it lost its status as a planet. Neighborhood clearing means that the area of space near which it orbits the Sun is stripped of larger bodies, having been sucked into the planet. It is clear that Ceres, like Pluto, does not pass these criteria: the asteroid belt in which Ceres resides is evidence of a “failed” planet that has not cleared its neighborhood. In fact, there are several relatively massive objects – Vesta, Pallas and Hygiea – also in the vicinity of Ceres.
Pluto maintained this distinction of the planet for 76 years, beginning with its discovery in 1930 by American astronomer Clyde W. Tombaugh. Downgrading of Pluto to a Dwarf Planet Still controversial, and not only among ordinary astronomers. A team of American scientists Published a paper in December In the scientific journal Icarus he said that “planet” should be defined as any geologically active celestial body. 1 co-author argue that we should say that there are “perhaps more than 150 planets in our solar system”; The paper claimed that the need to distinguish planets from moons is a cultural rather than scientific necessity, and hinders a proper understanding of astronomy.
“We found that during the nineteenth century the non-scientific public in the Latin West developed its own popular classification about planets that reflected the interests of astrology and theology, and that this popular classification eventually influenced scholars,” the scientists explained. They later concluded that “the use of the geophysical planet concept with subcategories of individual features (including gravitational dominance) makes the planet concept useful and profoundly insightful for communicating with the public.” They asserted that this did not happen in 2006 because “there was not enough time to sort out these issues”, with the resulting vote leading to a “deeper division in society”.
Ironically, even when Pluto was demoted, Ceres almost got a promotion. A pre-21st century proposal to define a planet had done so by describing a planet as having enough mass to be roughly round and orbiting a star without being a satellite of a planet or star per se. Had this definition been accepted, Ceres would have been the fifth planet from the Sun.
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