Ever since the discovery of Pluto in 1930, astronomers on Earth believed there was a total of nine planets in our star system. Together with Pluto, the others were Mercury, Neptune, Venus, Uranus, Earth, Mars, Jupiter, and Saturn. However, in 2006, the International Astronomical Union (IAU) reclassified planets changing our solar system forever. At their conference in Prague in 2006, scientists decided to demote Pluto the smallest ‘planet’ in our solar system to the status of Dwarf Planet, by a margin of 206 – 199.
Is our Solar System model wrong? Image Credit
Pluto lost its title in a controversial decision because according to the IAU, a large number of similar-sized objects to Pluto were discovered in the outer edges of our Solar System, and astronomers were supposedly having a hard time keeping track of them so experts decided to change the criteria, tightening up the entry requirements for a celestial object to enter our star system’s planetary club.
However, Pluto regained fame and hopes of returning to the solar system family after NASA’s New horizon Spacecraft beamed back stunning images of the ‘frozen’ planet in 2015. The images and studies revealed the possibility that there even might be microbial life on Pluto, following New Horizon’s close fly-by in summer 2015.
That’s when Jerry Stone from Spaceflight UK, has launched a campaign to reclassify Pluto. According to Mr. Stone, the definition introduced in 2006 by the IAU changed things a lot but created the opportunity for much smaller celestial objects and dwarf planets in our star system being described as actual planets.
Mr. Stone states that: “In 2003 they found UB313, roughly the same size as Pluto, so if Pluto was a planet, that would have to be one. You had Ceres between Mars and Jupiter – another world in our sky. At the time, a planet was a circular object that circled a star and shine by reflective light. The IAU debated this at their conference in 2006.”
Thus, a new definition was proposed and the new candidates included Ceres, Eris, Pluto and its biggest moon Charon and UB 313. According to to the new definition proposed in August of 2006, a planet is a celestial body which:
- is in orbit around the Sun,
- has sufficient mass to assume hydrostatic equilibrium(a nearly round shape).
But according to Mr. Stone, the smaller planets still qualified under that definition. The IAU then brought in another criterion: in order to be considered a planet, a celestial object must also have “cleared the neighborhood” around its orbit.
Speaking about the controversial issue at the International Astronomy Show in Stoneleigh Park, Mr. Stone said: “But the new definition was only for planets in our solar system. Why did we need one for our star system and for others in other solar systems? What about planets that free flow and do not go around any star, it is a possibility, and we might have found about eight. Jupiter does not orbit the sun so Jupiter is not a planet according to the new definition.”
Smaller sized objects in our solar system like Pluto were kicked out of the planetary family because the definition clearly states a planet must have cleared orbital areas of debris.
Mr. Stone rightfully argued that the fact that there are still meteorites striking our planet, Earth hasn’t cleared its orbital area of debris, but neither has Mars and Jupiter due to the asteroid belt between our neighbouring planet and Jupiter. Interestingly, the same can be said about Neptune or Uranus he claimed.
“So only Mercury, Saturn, and Uranus, should be planets following the new definition. It is the result of a poor definition. The revised definition was done in about four days. If you rush your work you get sloppy results,” added Mr. Stone.
So how many planets are in our solar system then?
According to researchers, in our galaxy alone there are over 200 billion planets that are not differentiated whether they are dwarf planets or not.
“Our sun is a yellow dwarf star, but it is still a star. They have identified dwarf galaxies and they are still galaxies. So Pluto most definitely is a planet. And there is nothing wrong with Jupiter, so we have four terrestrial planets, four gas giants, and five dwarf planets, making 13 planets in the solar system. “They have since found eight other dwarf planets so that makes 21 planets,” argued Mr. Stone.
According to Mr. Stone, by the new definitions, Mike Brown Professor of Planetary Astronomy at the California Institute of Technology, identified a list of a total of 384 new objects in our solar system likely to be big enough to be dwarf planets – and therefore planets.
“With the eight official planets and the five official dwarf planets that make 397 in total. It means the solar system is still growing, So is Pluto a planet? Yes,” said Mr. Stone.