What Is The New Definition Of A Planet And Why Pluto No Longer Qualifies?

For several generations, Pluto had been fondly called the “little guy” on the solar system block.

Once the ninth planet and farthest away from the sun, Pluto has been bumped.  That’s right … now this frozen celestial body is known as a dwarf planet.

A little over seventy-five years has gone by since Clyde Tombaugh spotted Pluto, a little flashing light on the photographic plates he was perusing.

Tombaugh realized that this light he spotted was past Neptune in the solar system line-up, big enough in mass to be spotted and that it orbited around the Sun.

Since that time, the public, on the whole, figured that the discovery of Pluto was the final addition to the planet line-up in the solar system, where the Sun provided the central point that all nine planets orbited around.  Mercury, Venus, Earth, Mars Jupiter, Saturn, Uranus, Neptune and Pluto became the recognized mantra that all school kids had to memorize in science class.

As telescopes and other scientific instruments became more sophisticated, a lot littler objects have been tracked and recognized as asteroids and comets, like Halley’s Comet just provided fodder for our fascination with the heavens.

Because of the number of new celestial objects being found in our solar system, this increasing phenomenon sparked scientists and astronomers to create new parameters of what defines a planet.

With a lot of dissention among the many members of the International Astronomical Union, the major governing body of Astronomy in the world, they came up with a basic new definition of a planet.  Unfortunately, Pluto did not fit the bill.

So, in late 2006, the International Astronomical Union officially declared that the solar system now only has eight planets in the line-up instead of nine.  Pluto became a dwarf planet.  So, what constitutes a planet and what is a dwarf planet? Read on to find out.

New definition of a planet:

The new definition of a planet, as designated by the International Astronomical Union, states that a planet is a celestial object or body that is in orbit around the Sun.

In addition, in order to be a planet, this celestial object must have enough mass to have its own gravity, so that it can resist against unyielding forces, so that it creates a round “planet-like” shape.  Also, a planet must completely clear an orbit around the sun or “clear the neighborhood” as astronomers like to call it.

A dwarf planet, as Pluto is now classified, has two characteristics in common with full-fledged planets.  It is a celestial object that orbits around the Sun and it also has enough gravity to beat the severe forces against itself in order to create a relatively round circumference.  However, the remaining characteristics of a dwarf planet set itself apart.

For one, a dwarf planet has not “cleared the neighborhood” during its orbital path around the sun.  Secondly, a dwarf planet must not be a satellite. (A satellite is a celestial body that typically orbits a planet or other mass that is larger than it and not made by man.  Moons are also known as satellites.)

With this new designation of Pluto as a dwarf planet, now the solar system is comprised of the eight planets from Mercury to Neptune as well as a number of smaller celestial objects like comets, asteroids, and anything else that cannot be classified at a satellite, also known as small solar system bodies or SSSB. While these new definitions for planets follow some controversy, many scientists agree that it was time to have a formal definition for a planet.

The universe is vast and our solar system still holds many secrets and undiscovered celestial bodies. Without some clearly defined parameters, any new discoveries would be up to intense scrutiny and debate on how they should be classified.  The new definition of a planet should help when classifying new discoveries.

Popularity: 1% [?]