We Only Have 8 Planets In Our Solar System Now (Pluto Removed)

[Reno]

http://www.cbc.ca/story/world/national/2006/08/24/pluto-planets.html

They finally decided that Pluto is not a planet.

Little Pluto, formerly the solar system's smallest planet, has been stripped of its status by the International Astronomical Union, reducing the number of planets to eight.

The new guidelines — introduced in Prague on Thursday after a week of debate by the 2,500 astronomers at the organization's conference — define what is a planet and what is not. Pluto didn't make the cut.

Pluto has been considered a planet since its discovery in 1930. Under the new guidelines, it's now considered a "dwarf planet," leaving eight planets — Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Pluto, which is smaller than Earth's moon, doesn't fit the new criteria for a planet: "a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a … nearly round shape, and has cleared the neighbourhood around its orbit."

Pluto doesn't qualify because its orbit is inclined relative to the rest of the solar system and crosses over the orbit of Neptune.

NASA said Thursday that Pluto's designation as a dwarf planet would not affect its $700-million US New Horizons spacecraft mission, launched earlier this year. The spacecraft will reach Pluto after a 9½-year journey.

The IAU also introduced a third class, "small solar-system bodies," for objects smaller than dwarf planets, such as asteroids and comets, that orbit the sun.

Astronomers have been working without a solid definition of a planet since the days of Copernicus. The new definitions fill that void.

Just a week ago, the IAU's leader suggested a different definition for planet that would have included Pluto, its moon Charon, the asteroid Ceres and a recently discovered object, 2003 UB313, which is slightly larger than Pluto and was nicknamed Xena.

The plan was unpopular among the astronomers at the conference and led to the long debate.

Not first time 'planet' demoted

It wasn't the first demotion for a body formerly considered a planet.

Ceres was considered a planet when it was first discovered in 1801.

However, after the size of Ceres was determined and other bodies were found in a belt between Mars and Jupiter, it lost its status. The term "asteroid," meaning "star-like," was coined to describe them.

Three other "planets" became "asteroids" at the same time.

Among other implications, Thursday's new definition means students will have to abandon current mnemonic devices that helped them remember how the planets are arranged in order from the sun.

For example, "Mark's Very Extravagant Mother Just Sent Us Ninety Parakeets" helped them recall that the order was Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.

Perhaps they can now return to the pre-1930 mnemonic: Mary's Violet Eyes Make John Stay Up Nights.

 

[IglooDame]

Whew... much ado about nothing, it turns out.

 

[Perfection]

Well, normally I would strike again, but since this is a major development, I'll just let it stand but supply a whole bunch of links

The other threads on the IAU redifiniton
http://forums.civfanatics.com/showthread.php?t=183524
http://forums.civfanatics.com/showthread.php?t=182968
http://forums.civfanatics.com/showthread.php?t=182220
A recent debate thread:
http://forums.civfanatics.com/showthread.php?t=175845
My proposed definition scheme:
http://forums.civfanatics.com/showpost.php?p=4220429&postcount=24

Old semi-relevant threads:
Size of the Planets, A Comparison
http://forums.civfanatics.com/showthread.php?t=175804
Astronomy Picture thread
http://forums.civfanatics.com/showthread.php?t=61837
What is a planet?
http://forums.civfanatics.com/showthread.php?t=130544
Tenth Planet Has A Moon
http://forums.civfanatics.com/showthread.php?t=130437
The 12th Planet (funny!)
http://forums.civfanatics.com/showthread.php?t=98113
tenth planet?
http://forums.civfanatics.com/showthread.php?t=81976

On the topic I find this to be in the ball park of what I want, though the term "dwarf planet" is kinda silly, I'd prefer something like mesoplanet or planetoid.

 

[Spartan117]

i want my pluto

 

[CaptainF]

Damnit. Those astronomers have no respect for tradition.

 

[Eran of Arcadia]

Yeah, insisting that the earth revolves around the sun despite thousands of years of tradition!

But as for me, I couldn't be happier about it. I have had an irrational dislike of Pluto's status ever since I heard they were considering changing it. I still don't know why, but there you go.

 

[Perfection]

i want my pluto

Don't worry! Pluto is still gonna be around! He's just classified with all his other TNO friends! I mean Pluto never really fit in with the Planets with all thier gas and rocks and orbital domains, he'll be better off with his own kind being able to hang out with fine folks like Orcus and Quaoar.

Damnit. Those astronomers have no respect for tradition.

Actually this fits quite well in with tradition! Ceres was considered a planet until it was discovered to be one of many asteroids then it got reclassified, Pluto is just getting the same treatment!

 

[Stegyre]

Oh, come now, we all know the real reason Pluto has been stripped of its status: it was that sordid incident a few years back involving the under-age Persephone:

http://www.theoi.com/Khthonios/HaidesPersephone2.html

(If only I could figure out how to do images, we could show the Bernini sculpture.)

 

[Eran of Arcadia]

Yeah, better for Pluto to be one of the biggest TNOs than the very smallest planet. This is all for the best. We are concerned for the needs of Pluto as an individual, we aren't just being "mean" or "unfair".

 

[The Last Conformist]

Count one for common sense.

 

[Spartan117]

pluto is the under dog, just getting shoved around. getting labeled with dwarf and such. this is only meant to make it seem insigificant.

 

[Perfection]

pluto is the under dog, just getting shoved around. getting labeled with dwarf and such. this is only meant to make it seem insigificant.

Yeah, that's why I like the term mesoplanet or planetoid better then "dwarf planet", give him a special category for him and his homies.

 

[Riesstiu IV]

That Plutonian Empire guys is gonna be pissed when he hears about this.

 

[fenceman]

Let us not think of this so much as the loss of a planet, but the addition of three dwarf planets

 

[The Last Conformist]

pluto is the under dog, just getting shoved around. getting labeled with dwarf and such. this is only meant to make it seem insigificant.

Well, at ~4% of Mercury's mass, it is pretty insignificant.

 

[GenMarshall]

i want my pluto

Here you go, the planet Pluto

I will still see Pluto as our 9th planet (Pre-2006 proposal to reorganize the planets)

 

[Perfection]

I will still see Pluto as our 9th planet (Pre-2006 proposal to reorganize the planets)

Why do you see it that way?

How do you see UB313 (Xena)?

 

[Tee Kay]

Neptune: Hahahaha! That'll teach him not to cross my orbit!

I would still see Pluto as the ninth planet for nostalgic reasons, but also as a KBO as the same time.

 

[spankey]

With this definition: "a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a … nearly round shape, and has cleared the neighbourhood around its orbit."
and the admission that :" [Pluto] crosses over the orbit of Neptune"

would it follow that Neptune is not a planet either, since it hasn't cleared the neighborhood around its orbit?

 

[Gogf]

That brings up an interesting issue: Pluto and Neptune should eventually collide. Neptune will probably remain while Pluto won't.