how many planets do we have now?

Question

they were talking about downgrading pluto to an asteroid bringing the planets in our solar system down to eight because if Pluto is a planet then so are several other chunks of rock in the sky taking us up to 12 or something: exactly what did they decide and how many planets do we have now?

Answer 1

Eight

The International Astronomical Union (IAU), the official scientific body for astronomical nomenclature, meeting in Prague on 24th August 2006 defined "planet" as a celestial body that:

(a) is in orbit around a star or stellar remnants;

(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape;

(c) is not massive enough to initiate thermonuclear fusion of deuterium in its core;

and,

(d) has cleared the neighbourhood around its orbit.

Our solar system is considered to have eight planets under this definition: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Three bodies which fulfill the first three conditions but not the fourth are now classified as dwarf planets: Ceres, Pluto and 2003 UB313

Answer 2

We have the same number of planets that we have always had. The question is what, exactly, is a planet. For decades Pluto has been considered a planet. Recently, a gaggle of astronomers got together and voted it off the list. It's not so much that they disliked Pluto, as they redefined what constitutes a planet, and Pluto has neither the girth nor the stability. It doesn't mean it doesn't still exist, just that it now gets lumped in with the outer planetoids like the newly discovered Xena. So now we have only eight planets, of which most of us live on the third.

Cheers!

Answer 3

there are now 8 planets in the solar system, pluto has indeed been demoted to the position of dwarf planet, also in this category are plutos companion Charon, a large asteroid found in the belt between mars and jupiter called Ceres and a recently discovered object nicknamed xena.

Xena is the one that kicked the whole debate off, it was the first object found in over 70 years that we knew was definately bigger than pluto and for a while was unofficially named the 10th planet.

astronomers and planetary scientists have a list of objects that they thought could potentially be bigger than pluto and therefore planets, initially the International Astronomical Union (IAU - the people who decide these things) were considering adding Charon, Ceres and Xena to our list of planets, they then realised that this would open the floodgates, if all the objects on the potential list turned out to be bigger than pluto, then in 20 years time we could have 10's or even hundreds of planets in our solar system.

as we improve technology we can find smaller, darker and more distant object that would add to our planet population, a solar system with 100 planets is meaningless and unwieldy, the decision to demote pluto was made with the intention of avoiding this problem.

Answer 4

8

Answer 5

Eight on the team. 3 dwarf planets: Ceres, Xena and Pluto. And everything else is a SSSB (Small Siolar System Body), which includes comets.

Answer 6

Unfortunately Pluto did not come up to scratch and can't call itself a planet anymore - so 8 it is. I believe that it is just a ball of ice with several other celestial bodies not categorised as planets being larger.

Answer 7

It's eight. They down graded Pluto last week in Prague. As for the other rocks, they have never been confirmed as planets.

Answer 8

a few days ago. I think you're right they did decide that pluto should not be classed as a planet, nor the planet they discovered about 18 months ago, both are too small.

Answer 9

we only have 8 now. Pluto is considered as DWARF PLANET already and not included in the standard SOLAR SYSTEM we used to acknowledge.

Answer 10

Personally, I have 3.