according to recent theory, what is definition of planet?

Answer 1

The IAU (International Astronomers' Union) is *proposing* that a planet be defined as any solar system object which (1) orbits a star without being a star itself, and (2) is massive enough to have collapsed under gravity into a spheroid shape.

The definition will be voted on later this week; if it's ratified, then our solar system will immediately gain three new planets (Charon, Ceres, and 2003 UB 313, which is sometimes nicknamed "Xena" though that name will certainly not be its official one), and at least a dozen more will be considered for planetary status later. Pluto, which many thought likely to be demoted from planetary status, will remain a planet -- in fact, it will be a double-planet with Charon, which was formerly considered its moon.

For more info, see the link below. Hope that helps!

Answer 2

The term planet has existed for thousands of years, not only in science but as part of wider culture, applied in its long history to everything from divination to environmentalism. That the solar system consists of the Sun and nine planets is a widely-held and often repeated idea. To date, however, no actual scientific definition of the word "planet" exists. 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.


In 2006, a proposal was brought before the International Astronomical Union to redefine the term "planet" so as to include other objects beyond the traditional nine planets which have been historically considered a part of the solar system.[1] The proposal is denoted as Resolution 5 for GA-XXVI; members of the IAU will vote on it on August 24, 2006 in Prague, Czech Republic.

The redefinition would recognise three new planets: Ceres, Charon, and 2003 UB313. It is presumed that, after more observation and discussion, astronomers will accept more objects in the solar system as meeting this new definition.

Answer 3

The problem here is that this isn't based on theory, it's merely classification and definitions.

By theory, I know of no reason that Ceres should be a planet, and other large asteroids are not. Ceres just happens to be a little bit bigger than, say Vesta, and so is rounder. So, proposed definitions would make Ceres a planet.

The definition of "planet" as a technical term is currently not agreed upon; all the proposed changes you've heard about are just that: proposed changes, not yet decided upon. So don't get too caught up on the definition - just yet!

check out:

http://skytonight.com/news/home/3601616.html

Answer 4

I would say that the following are minimum characteristics of planets.

1 & 2 below are arbitrary, you may prefer other variables.

1. Minimum Mass. 10^20 Kg. (about 1/100th the mass of Pluto).

2. Minimum Diameter. 1,500 Km (about 900 miles)

3. Orbit. Must be in orbit around a sun, and not a planet (therefore, Luna is not a planet, even though it's larger than Pluto).

4. Distance from sun. Not relevant, as long as it is clearly in orbit around the sun. Therefore, a massive sun may have planets dozen's of light-years away.

5. Is not itself a sun. That would be a binary or higher system.

6. Must not be in interstellar space, not associated with a sun or suns.

7. Not in a field of other bodies with the same approximate orbit. That would leave out anything in the Asteroid Belt and Oort Cloud. So, I say that Pluto is a planet.

Now, how about "Xena" (aka, 2003 UB313)? To Hades (Greek God of the underworld) with conventions for naming planets. Xena is perfect. And Gabrielle for the moon. If they can name a comet "Hale-Bopp" why not a planet after the Warrior Princess.

Now, I disagree with Charon and Ceres getting a promotion.

One shares an orbital field with thousands of smaller objects that have more mass in total that Ceres.

The other circles a planet, it's a moon. If Charon is a planet, then what about Luna and some moons of Jupiter and Saturn?

Answer 5

Well according to wacky_racer's theory :o), the definition of planet is a plan to laid out the visible sky into the plane and it is as it is and should be ended in it. As for a fact, scientist rides and base on it(planet is what I mean).

But don't blame me if you think I'm wrong because all answers answered is right.

Peace.

Answer 6

According to the scientists that decide if a planet is a planet......as long as a rock formation is more than 1000km in diameter and is basically a 'round' shape, whether it be made of rock or whatever......then it can basically be considered a planet........

Answer 7

The current definition is:
1) Objects with true masses below the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity) that orbit stars or stellar remnants are "planets" (no matter how they formed). The minimum mass/size required for an extrasolar object to be considered a planet should be the same as that used in our Solar System.

2) Objects with true masses above the limiting mass for thermonuclear fusion of deuterium are "brown dwarfs", no matter how they formed or where they are located.

3) Free-floating objects in young star clusters with masses below the limiting mass for thermonuclear fusion of deuterium are not "planets", but are "sub-brown dwarfs" (or most appropriate name).

Answer 8

The primary criteria are a stable orbit and sufficient mass to form and maintain a spheroid shape under its own gravity.

Answer 9

there is definately a need for the creation of a standard law for the declation of a general celestial plane orbititng around the sun..and till now there is none..i guess

Answer 10

1)the object should have atleast 500 miles as diameter
2)it should revolve around sun
3)its weight should be abt 1/12,000 times as of earth.