Planet Pluto?

Question

What are your thoughts. It has been a planet for so long do you think it is worth changing?

Answer 1

When it was discovered in 1930, nobody knew that objects like Pluto were pretty common outside the orbit of Neptune. So it was a bad decision then to call it a "planet." Since then, many similar bodes have been found in its vicinity, including its moon Charon, other large bodies like Sedna, and even a body larger than Pluto (2003UB313).

A very similar renaming happened to Ceres (between the orbits of Mars and Jupiter) back in 1801. First classified as a planet, it was soon discovered to be the first among a bunch of similar objects, and it was re-classified as an asteroid.

The problem was that there has never been, until now, a firm definition by astronomers as to what a "planet" is. The discovery of UB313 forced the issue.

So the IAU had a choice. If they defined "planet" to include Pluto, then there is no reason they could not include UB313, and Charon, and Ceres, and then additional asteroids like Vesta and Pallas, and other trans-Neptunian objects like Sedna, Quauoar. There are as many as 53 objects we know of that would fall into a similar category as Pluto.

To me, a definition that results in 53 planets, and always growing, would have been worse. (You worry about schoolkids and mnemonics? ... start adding names like Ceres, Charon, Xena ... and then next year they have to add (and pronounce) Quaoar ... and the year after that we add Vesta, Pallas, Ixion Orcus, Varuna etc. etc. to the things you have to memorize.)

The PR-sensitive thing to do would have been to simply declare Pluto as a special exception to the new definition. Unfortunately, that's just bad science ... you don't grant things "honorary" status just because of historical sentiment. A scientific definition applied inconsistently just erodes confidence that scientists know what their talking about.

Another thing to consider ... scientists are also thinking about the new planets we are starting to find orbiting other stars. They need to have a classification system that works well into the future.

So as much as I am sentimentally saddened by the news ... it is the scientifically correct thing to do.

Answer 2

Recently at the International Astronomical Union (IAU) General Assembly in Prague, astronomers decided that the Solar System has eight planets, and Pluto is not one of them. Instead, Pluto is a "dwarf planet."

To be a planet, the assembly ruled, a world must meet three criteria:

(1) It must have enough mass and gravity to gather itself into a ball.

(2) It must orbit the sun.

(3) It must reign supreme in its own orbit, having "cleared the neighborhood" of other competing bodies.

So, e.g., mighty Jupiter, which circles the sun supreme in its own orbit, is a planet--no adjective required. Pluto, on the other hand, shares the outer solar system with thousands of Pluto-like objects. Because it has not "cleared its own neighborhood," it is a dwarf planet.

This decision clarifies the vocabulary of planetary astronomy while simultaneously upturning 76 years of "Pluto is a planet" pop-culture. Will non-specialists heed Pluto's demotion? That remains to be seen. Meanwhile, according to the IAU, the Solar System has eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune; and three dwarf planets: Ceres, Pluto and 2003 UB313.

Answer 3

I believe the criteria used to determine whether a celestial body is a planet is overly complex and should be simplified. We're pulling human factors into determination. Size, mass, SHAPE, and composition should NOT be factored into the determination. Alien worlds must be given alien consideration - not a dogmatic narrow view based on human experiences.

Simply put, a planet should have two things:

1. A planet should maintains an orbit within a system. Otherwise it can be classified as an asteriod or comet.

2. A planet can be a statellite to zero or more stars. It cannot be a satellite to another planet.


-Leon S

Answer 4

I think that astronomers have to have a holiday on the company expenses, so they all meet in the west indes to discuss stupid topics that don't change anything.
Am I right in saying that it was something like 2,500 people who met to vote on whether pluto was a planet or not?
Absurd.
What a waste of time, effort and resources! If we're really committed to finding things out, we should be working on how to get there, not what to call things.

Answer 5

Yeah I was pretty peeved about it myself when I heard. It doesn't really help knowing that scientists would say people aren't supposed to have feelings about scientific decisions. It just makes them seem arrogant. However, the reasons are hard to dispute. Pluto is really a big chunk of ice that doesn't have enough gravity to be round like the planets. It doesn't have it's own orbit because it crosses the path of Uranus. Stupid Uranus!

Answer 6

Pluto has just as much a right to be a planet as anyother one... it isnt hurting no one...

and on now we have to come up with a new accronym to learn the planets..

Answer 7

I agree that it is necessary to have set criteria so there is no debate as to what qualifies. It still will be classified a drarf planet though. I am still taking it all in though but I agree with the change

Answer 8

Who really cares whether a hunk of stuff thousands of miles away from us is technically a planet or not. Leave Pluto be.

Answer 9

I am tired of hearing about it. That's my thoughts. All the problems going on and here are these scientists on the national news arguing over what to call a frozen rock out in the middle of nowhere that has nothing to do with us. Didn't you people used to do things. Where are all the Edisons and Einsteins? Now they just talk about their IQs and regurgitate old ideas. Then after that I got hear about what was going on in Tom Cruise's life.

Answer 10

No one would have believed in the last years of the nineteenth century that this world was being watched keenly and closely by intelligences greater than man's and yet as mortal as his own; that as men busied themselves about their various concerns they were scrutinised and studied, perhaps almost as narrowly as a man with a microscope might scrutinise the transient creatures that swarm and multiply in a drop of water. With infinite complacency men went to and fro over this globe about their little affairs, serene in their assurance of their empire over matter. It is possible that the infusoria under the microscope do the same. No one gave a thought to the older worlds of space as sources of human danger, or thought of them only to dismiss the idea of life upon them as impossible or improbable. It is curious to recall some of the mental habits of those departed days.