The Reason Why Pluto is No Longer a Planet

For 76 years, most people knew Pluto as the smallest and most furthest planet in our solar system. But now Pluto is no longer a planet. This was all due to Mike Brown, an astronomer from the California Institute of Technology, who discovered some objects beyond the known planets. One of those objects was a dwarf planet that we now call Eris. At the time, Eris seemed bigger than Pluto. The International Astronomical Union face a difficult decision. They either label all new objects as planets or narrow the definition of what is and what will be a planet. In 2006, they picked the second opinion which meant scientists had to decide by a vote where Pluto laid within this new definition. Pluto became a dwarf planet.


For an object to get planetary status, it must pass three tests;

1. This object must orbit the sun
2. This object must be round
3. This object must clear the neighbourhood of all other objects

In Pluto's defence, it does pass the first test. Pluto does make one loop the sun once every 248 year (So, you'd be lucky if Pluto did this in your lifetime). But this is why our moon is a moon. Our moon orbit the Earth rather than the Sun.
The second test, Pluto again passes. Pluto is large enough to become round due to the force of gravity pulling on any part on the rock which juts out to far.


However, it is the last test which sets Pluto apart from Earth, Jupiter and the 6 other planets. The solar system is messy which different sized planets having various amounts of pulling power. So there are many other objects such as sand and gas giants. Mars and Jupiter are planets because of the asteroid belt between them. Any orbit could bring either of these planets closer which because their gravitational pull could force the asteroids in any direction. Likewise with the other orbits, they are mostly clear of objects.
Pluto is a different case. It's path is something between an asteroid or a planet. Now that researchers are looking into the environment of Pluto. It no longer looks special. Instead of our furthest away planet, Pluto might be the closest member of the Kuiper belt. The Kuiper belt is a ring of an estimated trillion comets and ice balls which orbit after Neptune. 200 of those objects from the Kuiper Belt seemed big enough to case as a dwarf planet too.