why does the Pluto not belong to solar system anymore?

Answer 1

This should help with your definition of a planet...but there is lots of controversy..

The definition of "planet" has for some time been the subject of intense debate. Surprisingly, despite the term having existed for thousands of years, no scientifically accepted definition of "planet" existed before August 24, 2006. Until the beginning of the 1990s, there was little need for a definition, as astronomers had only a single sample within the solar system to work from, and the sample was small enough for its many irregularities to be dealt with individually.

However, after 1992 and the discovery of the myriad tiny worlds beyond the orbit of Neptune, the size of the sample rose from nine to at least several dozen. Following the further discovery of the first extrasolar planet beyond our solar system in 1995, the number of samples is now approaching hundreds. These new discoveries not only increased the number of potential planets, but, in their variety and peculiarity (some large enough to be stars, others smaller than our Moon) challenged long perceived notions of what a planet could be.

The issue of a clear definition for planet came to a head in 2005 with the discovery of the trans-Neptunian object Eris, a body larger than the smallest accepted planet, Pluto. In response, the International Astronomical Union, or IAU, which is internationally recognized by astronomers as the body responsible for resolving issues of astronomical nomenclature, released its final decision on the matter. According to their definition, a planet is a body that orbits the Sun, is large enough for its own gravity to make it round, and has "cleared the neighbourhood" of smaller objects.

Those objects which orbit the Sun and are round by self-gravity, yet have not cleared the neighborhood around their orbits are termed dwarf planets. Since that definition classifies Pluto as a dwarf planet, the official number of "classical" planets has fallen from the traditional nine to eight. This definition has not resolved all controversies, however, and the issues of what constitutes a planet are unlikely to be clearcut for some time to come.

Answer 2

The universe that we knew changed-Pluto has been demoted.
Pluto has always been a problem child. Its inclusion in the planetary family in 1930- when it was first discovered- has been hotly debated by astronomers.
This is because it is much further away than the eight other planets and, at 2360km in diameter, much smaller- smaller than originally thought, and certainly tinier than some moons in the solar system.
Under the new defination, a planet must meet three requirements: it must orbit the sun; be big enough for gravity to have shaped it into a round ball; and it must have cleared other objects out of its path.
It is this last rule that technically disqualifies Pluto, whose orbit overlaps with Neptune's. Pluto's path is also on a totally different plane compared to the other planets.
If no new celestial bodies had been discovered, there would probably be no need to do this. However, telescopes have been getting better, revealing dozens of distant objects that give Pluto a run for its money in the size department.
If Pluto were considered a planet, then many of these new bodies would have to be classified as planets as well.
And you would end up changing textbooks anyway- this time include 50 or more planets in the solar system.
Pluto has been reclassified as a "draft planet", which only has to orbit the sun and be round.
But it won't be alone. A small and frosty rock nicknamed Xena, measuring 3000km across, has been placed in this group along with Ceres, the biggest asteroid in the solar system. Many more objects are expexted to be included in this grouping.
Not all astronomers agree with the redefination, either. Some say that the new system is too complicated, or think that the word "planet" should not be used at all with smaller bodies.
It is "sloppy science", says a member of the team from the US that plans to send an unmanned spacecraft to fly past Pluto in 2015. He says there are many astronomers who feel the same way, and that they will fight to bring Pluto back into the family.

Answer 3

Pluto is still part of the Solary System. It is just that Pluto is now classified under one of the dwarf planets. Even the other dwarf planets, they are part of the Solar System. Seems like all natural planets or whatever in space is part of the Solar System. Don't count The International Space Station. Haha.

Answer 4

Pluto still belongs to the solar system. Some astronomers say it shouldn't be called a planet anymore.

Answer 5

Pluto still belongs to the Solar System. However, it is not a "planet" anymore since it's small size does not fit into the definition of a planet.
It now becomes a "dwarf" planet like some big asteroids and other similar sized objects like Ceres and Xena.

Answer 6

Because the Mickey and the Goofy Kicked The Pluto out.

Answer 7

"Planet" develop into finally defined by employing global Astronomical Union employing certain criteria and Pluto did not qualify anymore. It might want to: a million) Be in orbit round the solar, 2) Have sufficient mass to anticipate hydrostatic equilibrium (a virtually round structure) 3) Have "cleared the neighbourhood" round its orbit. The third criteria is the position Pluto did not qualify.

Answer 8

Pluto is still in the solar system . However its demoted from its planet status , the reason being it doesn't have it's own gravitational Pull

Answer 9

Pluto does belong to our solar sytem. Ever.

It is not officially considered as a "main planet" anymore but as a "PLANETOÏD":

Answer 10

Bcoz PLUTO is the name of the dog in the mickey mouse series cartoon.