How Would You Define a Planet?

It doesn't come easy asks: "The argument over the definition of a planet continues. So far, two definitions are favored but without much consensus so far: base the definition of a planet simply on an object's size. Pluto would be near the lower limit and the newly discovered Kuiper Belt objects could also qualify, giving us 10 or 11 planets so far; or define the single dominant body in its immediate neighborhood as the only qualifying object for planetary status. If no one body dominated (such as the millions of individual asteroids in the asteroid belt) then none would qualify for planetary status. In this case Pluto would be disqualified (Neptune would be the dominant body in Pluto's region of space), and the newly discovered Kuiper Belt objects would also fail to qualify. The International Astronomical Union (IAU) working group charged with pinning down the definition of a planet may vote on the proposals within the next two weeks (or they may decide to start all over again with something new). Maybe Slashdot readers can give them some help. How would you define a planet?"

Like this

[christurkel]

I would define it thus: An object is a planet if it has enough gravity to form into a sphere but not large enough to ever had fusion start in its interior and has cleared its orbit of debris left over from its formation. This would allow Pluto to remain a planet, as well as "promote" Sedna to planet stus but rule out Ceres.

Obligatory Wikipedia Link

[Anonymous Coward]

The definition of a planet is disputed. Please see [[Definition of planet [wikipedia.org]]] for more information.

Although planets are the principal component of the solar system other than the sun, a precise definition of the term is surprisingly elusive. This article details the questions that may arise when trying to formulate a strict definition of the word.

For most astronomers the issue will be decided by the International Astronomical Union [wikipedia.org] (IAU). According to a published report from Nature magazine [nature.com] (corresponding entry at BugMeNot [bugmenot.com]), the discovery of 2003 UB313 [wikipedia.org] (which is a Kuiper Belt object bigger than Pluto) has forced the issue. An IAU committee which had already been working on a definition is now expected to promulgate one soon.

Re:anything with a roman god name

[kfg]

Terra Mater (Mother Earth)is not commonly held to be the same as the Goddess Bona Dea (Fauna). They would typically have seperate shrines, often in the same area, built by the same people. One is a personification of Earth itself, the other of living things. Of course here and there the lines might well blur.

I am fauna, but not terra. The child, but not the mother. I come from, but do not share identity.

In any case, the current official name of the earth is Earth, which is Germanic.

http://seds.lpl.arizona.edu/nineplanets/nineplanet s/earth.html [arizona.edu]

KFG

Re:magnetic field

[phageman]

Ignoring for the moment the fact that the gas giants aren't rocky or have molten cores, even Mars wouldn't qualify. Its core cooled and solidified several million years ago, killing its geodynamo (which BTW, may be the reason it lost its water and most of its atmoshpere).

Sigh.

[porkchop_d_clown]

What the heck do they teach kids these days?

Saturn and Uranus were titans - beings that came before the gods. Neptune was named in modern times, but they kept the roman naming tradition, same with Pluto, Roman god of the dead.

And then they proceeded to waste all the other greek and roman names on every rock, brick and crater they could find which is why we're reduced to naming moons after Shakespearean characters.

The naming of Charon was a slick trick - the discoverer specified that the name be spelled like the name of the mythical figure, but that the name be pronounced "Sharon" - which happened to be the guys wife.

Re:All Roman

[joranbelar]

Just for completeness: Saturn comes from Greek Cronos, Uranus from Greek Ouranos, Pluto from Greek Hades.

Re:anything with a roman god name

[Anonymous Coward]

ParnBR was probably pointing out "Earth" is the official name only *in English*. In Portuguese it's Terra. In Spanish is Tierra. "Earth" is not the universal name for this planet.