[X] My Assistant

[abalone]

OK --
If you want people to feel like they have a place in a larger Universe, you need to give them relatively "small" chunks to deal with.  Giving school kids ever-widening chunks (Earth as a planet, Earth/Moon System, Inner Solar System, Solar System) you keep the number of elements of each "chunk" under 10.  That seems to be a good limit, since anything that gets a lot more complex is difficult for an average person to handle in one "chunk."

So, I think it is important to give people some kind of system that identifies a Solar System consisting of a number of objects (in the vicinty of 10 or so objects) that they can grasp in one "chunk." 
-the other Doug

I think I agree more with Alan S that if you want to give people a taste of the enormity and vastness of the universe, to challenge their povincial view and give them a feel for our place in it, the more planets the better, so lets be generous and not limit ourselves to a 19 century perspective. It is often difficult for us to make a quantum leap and accept that reality is no longer represented our old neat picture of the solar system.

In teaching basic astronomy to students I find it difficult even to give them a rudimentary understanding of say the enormous distance to the nearest star with respect to the size of our solar system and how this makes the prospect that we have been visited by aliens so unlikely. Lets not hide the truth, a solar system is a lot more interesting the a few planets and moons.

[abalone]

  It's obvious that human beings need to classify things into systems
-the other Doug

Classification is a good and noble scientific cause but the group of bodies orbiting our sun that we call planets dont have a lot in common. Any classification system that puts Jupiter in the same group as say Mars or Mercury is not really of any scientific relevance and more for lay media consumption. It would be difficult to convince me that Mars has more in common with Jupiter than it has with Pluto.

[AndyG]

Classification is a good and noble scientific cause but the group of bodies orbiting our sun that we call planets dont have a lot in common. Any classification system that puts Jupiter in the same group as say Mars or Mercury is not really of any scientific relevance and more for lay media consumption.

Absolutely! The only time that Mars and Jupiter really had anything in common was in the eyes of pre-telescopic ancient cultures. Planets - πλανήτης - "wanderers". Not a bad description a few thousand years ago, but really rather redundant today, especially for new-found planets that require 30cm+ scopes to even see...

Cast Pluto into the KBO bin, I say! There's 4 gas giants and 4 terrestrial planets. Everything else can be organised by groupings: asteroids, comets, satellites, etc.

Andy G

[ilbasso]

Our taxonomic system for life went through some major changes once we discovered how to use nuclear and mitochondrial DNA to map the evolution of species. Some beings that "clearly" fell into one category and thought to be related to others, that on the surface apepared to be similar, are now thought to be completely different.

Is there a similar way in which we might classify stars/planets instead by how they evolved? E.g., are they primarily plasma, gaseous, rocky, or icy? Or do they have molten cores or not?

[dvandorn]

Don't delude yourselves, guys -- there is a far larger percentage of the world's population out there who are terrified by the increasing complexity we can now see in the Universe, than are awe-struck and delighted.

One of the reasons so many people in this world retreat into incredibly narrow and limiting, but very well-defined, roles and world-views is because facing up to how complex the world *really* is scares the living daylights out of them.

Since scientists and like-minded individuals rarely, if ever, have to deal with those people in any context other than the extremely mundane, we tend to forget that they're out there. But they are, and they outnumber us hundreds to one. (Note that you'll rarely see one of these people at a lecture by an astrophysicist -- except perhaps to demonstrate against the "relentless march of science" as if it's a bad thing, or loudly proclaim that "your science is all false becasue my god told me so." Just Google up some discussions about Creationism and its teaching in American public schools, if you don't believe me.)

Not that we need, as a culture or as individuals, to hide from the ever-more-complex Universe that is unfolding before us. Just that we need to understand that a vast majority of the human populace is irrational and fears this trend towards complexity-beyond-their-ability-to-understand, and that we need to take that at least somewhat into account when we design classification systems.

(Of course, there is always that relatively small percentage of scientists who *glory* in making their classification systems as complex and unapproachable as possible, so that the average person out there will confuse the system with magic, and confuse the scientist with a magician... but those ego-maniacal scientests tend to be few and far between. I think most of them work for ESA, though... *sigh*...)

-the other Doug

[JRehling]

In our little private "Planetary Sciences" webgroup, Ron Baalke quoted Mike Brown himself as saying yesterday: "Based on Spitzer measurements, 2005 FY9 is confirmed to be smaller than Pluto." Unfortunately, he didn't say how much smaller.  But at any rate the Revolution is now upon us: depending upon what size you use as a dividing line, the Solar System no longer has 9 known planets.  It now has 10 or 11, or else it has 8, or else (if you follow Alan Stern's lead) it has a hell of a lot more.  What we are really going to have to tell the schoolkids, of course, is that the question from now on will be forever ambiguous.

If I were designing a roster of solar system entities for fifth grade classrooms for the 2006-7 school year, I would have it read something like this:
Sun, Mercury, Venus, Earth, Mars, asteroids, Jupiter, Saturn, Uranus, Neptune, Pluto, [Whatever name 2003 UB313 ends up getting], comets, Kuiper Belt. (Yes that list ends up sounding like the roster of Santa's reindeers, which might be a nice way to get kids to remember some of it.)

If the number of things of planetlike size gets to be much bigger, it will start to be cruel to expect wee little kids to remember them all, which may merit dropping individual mention of everything past Neptune -- that's not a scientific measure, but a pedagogical one.

[tedstryk]

If I were designing a roster of solar system entities for fifth grade classrooms for the 2006-7 school year, I would have it read something like this:
Sun, Mercury, Venus, Earth, Mars, asteroids, Jupiter, Saturn, Uranus, Neptune, Pluto, [Whatever name 2003 UB313 ends up getting], comets, Kuiper Belt. (Yes that list ends up sounding like the roster of Santa's reindeers, which might be a nice way to get kids to remember some of it.)

If the number of things of planetlike size gets to be much bigger, it will start to be cruel to expect wee little kids to remember them all, which may merit dropping individual mention of everything past Neptune -- that's not a scientific measure, but a pedagogical one.

In the case that too many planets are found, It might be useful to retain a name like Kuiper belt, and teach that it contains lots of asteroids, comets, and planets. So there could be the Mercury - Neptune sequence, and then the "Objects of the Kuiper Belt."

[Guest_spaceffm_*]

For all interested in sizes i made 2 little Diagramms.
The First contains earth, some moons, biggest planetoids, some tno ect.

All sizes of all shown bodies are correct and in the same scale to each other as far as known.
Of course there it is not made public a definite diameter of 2003 UB313, 2005 FY9 und 2003 EL61 ( +b ).
2003 UB313 has a diameter of 2800km ( latest status ) in my graphic.
2005 FY9 has 1600km, 2003 EL61 has 1500 km with b aprx. 250km.

The 2nd graphic shows the first together with Jupiter...

Normal
used without credt so editid out,,, too bad

Before using it somewhere else please ask and give credit, i worked 6 hours in total time...Puh...thx



How small Enceladus is, but so activ...
So size does not always matter...

[gpurcell]

At what mass will a body have a differentiated core?

[Rob Pinnegar]

One of the reasons so many people in this world retreat into incredibly narrow and limiting, but very well-defined, roles and world-views is because facing up to how complex the world *really* is scares the living daylights out of them.

I guess that pretty much sums up people like Moon Hoaxers. If you're going to believe that astronauts landed on the Moon, you have to accept that there were (and still are) large numbers of engineers and scientists out there who were smart enough to figure out how to do it. For some reason that makes certain people feel small. It's easier for them to believe that it was all made up.

[tedstryk]

It might be cool to add Ganymede, since it is the largest moon, and Europa, since it is such a hot topic. Great graphic!

[ilbasso]

And don't forget Venus! (I know, and Saturn, and Uranus, and Neptune...)

I agree, cool graphic!!! Thanks for posting it!

[Decepticon]

That is a Great chart!

Very few of those on the net. And the ones that are out there are not updated.

[abalone]

Here's something to consider

Brown argues that astronomers cannot control what gets called a planet. "Our culture has fully embraced the idea that Pluto is a planet and scientists have for the most part not yet fully realized that the term 'planet' no longer belongs to them," he says.
"Everyone should ignore the distracting debates of the scientists, and planets in our Solar System should be defined not by some attempt at forcing a scientific definition on a thousands-of-years-old cultural term, but by simply embracing culture," says Brown. "Pluto is a planet because culture says it is." And, he adds, that means his new find is a planet too.
http://www.nature.com/news/2005/050801/full/050801-2.html

[Benoît]

Here's something to consider

Brown argues that astronomers cannot control what gets called a planet. "Our culture has fully embraced the idea that Pluto is a planet and scientists have for the most part not yet fully realized that the term 'planet' no longer belongs to them," he says.
"Everyone should ignore the distracting debates of the scientists, and planets in our Solar System should be defined not by some attempt at forcing a scientific definition on a thousands-of-years-old cultural term, but by simply embracing culture," says Brown. "Pluto is a planet because culture says it is." And, he adds, that means his new find is a planet too.
http://www.nature.com/news/2005/050801/full/050801-2.html

There was a time when culture said the earth is the centre of the universe and the sun as everything else rotates around it. That cultural icon was challenged by science with a nice mesure of success.

It would be a shame to let culture intimidate science.