Comments on Mike Brown's Planets: Planetary Placemats

Well Dr Mike Brown is certainly the "Dan Brown" on...

2009-12-18T01:04:48.026-08:00

Well Dr Mike Brown is certainly the "Dan Brown" on writing exciting stuff on the objects at the cold & dark edge of our Solar system...
Phill
Belgium

Mike, love the final planetary placemat. I'd buy ...

2009-10-22T16:18:49.451-07:00

Mike, love the final planetary placemat. I'd buy several of those. Matt, we had a planet walk like that set up in DC for a while. I loved the idea, but the walk grew quite long near the outer reaches of the solar system (although I guess that was the point!). Simeon, feel free to drop by any time and paint the ceiling of my sons' bedroom. I know they'd appreciate it. ;)

hey mike, i hope you don't mind my saving your fin...

2009-10-21T07:34:16.240-07:00

hey mike, i hope you don't mind my saving your final placemat image to my desktop; i'm thinking of tweaking the colors and using it for my desktop background =)

i haven't been able to get the idea of it out of my head since i first read this post so...i figured i'd come back

Oh My God, this is perfect! As a elementary teach...

2009-09-20T13:40:34.147-07:00

Oh My God, this is perfect! As a elementary teacher, I am constantly battling small children's ideas, as well as other adults (teachers, no less) in giving up the idea of pluto as a separate planet. I love showing all the other TNO/KBOs and asteroids on my planetary wall! Now the placemat idea #3 is perfect for me to show my students! I think this might actually help some adults get the right idea! Thank you! Thank You! from science teachers eveywhere!

It occurred to me that you can show relative sizes...

2009-09-16T16:59:28.055-07:00

It occurred to me that you can show relative sizes and distances without making a linear map. A joke example is the New York-centric map where
distances scale negative-exponentially with distance from NY.
After some experiments, I decided a power function preserved information better.

http://openaccess.org/~flipandzeke/zeke/images/SoSyMap34.pdf

maps the Solar System with both diameters and semimajor axes scaled as a 3/4 power.

May I make a couple of quick suggestion for your p...

2009-09-16T03:59:03.536-07:00

May I make a couple of quick suggestion for your placemat? You could restore the relative distances by scaling the x-axis just as you did in your first attempt, but keep the planet scales the same as in your last.

Draw vertical lines down the paper showing the orbital distances of all of the bodies which are primarily orbiting the sun. Each planet would then be drawn horizontally centered on it's orbit line (vertically placed to be ascetically pleasing). For planets with high eccentricities, the orbit line could be two-toned. A light color bar displaying the full width of the orbit, and a darker color for the mean orbital distance.

The moons could also be restored on this map by rendering them on small circles, with similar distance and size scales.

Mike, This isn't a placemat, but the ceiling of m...

2009-09-01T07:38:29.042-07:00

Mike,

This isn't a placemat, but the ceiling of my daughter's room. I did this about 6 months ago when she started getting interested in learning about "outer space" (she's 5).

I put all of the planets, the larger moons, plus the dwarf planets and named TNOs. The sizes are correctly scaled, and the distances from the sun are correctly scaled (of course not on the same scale as the sizes).

Everything from the Sun to Saturn (you can see Ceres and some asteroids if you squint)

Looking towards the outer solar system (the named TNOs are there after Neptune, but I don't have a good picture uploaded that shows them well).

I thought you might like it.

Mike: I realize you've got lots of other things on...

2009-08-31T19:22:54.541-07:00

Mike: I realize you've got lots of other things on your mind right now (like the fate of astronomical landmarks) ... but all the hubbub put me in a mind to check back and see that you answered my post. No, I don't think you (or nature, for that matter) are limiting the list to eight. In fact, I like the fact that even on the scaled-down version of the placemat, I can squint my eyes and see Ceres and about eight of the Kuiper Belt objects as definitely distinct, not all that much smaller than Mercury. (Eris is about half the width of Mercury, the next planet up ... while Earth is about a quarter the width of Neptune, the next planet up.)

I also like the fact that there are all those other spots on the mat. That's just as it should be. I worry that by artificially limiting the list to eight (or perhaps four, if a Neptunian was in charge of the job), folks limit their view of the solar system when it actually should be widened.

@Tom: Yes, I get excited about Uranus and Neptune!...

2009-08-29T06:10:45.062-07:00

@Tom: Yes, I get excited about Uranus and Neptune! (Especially Uranus!)

I'd LOVE to see a mission like Cassini to each of those big planets, as I expect that they could discover lots of interesting stuff out there.

@Mike Brown: Thanks for this article! I never really thought about that when looking at depictions of our solar system. Of course I knew that Pluto was much, much smaller than usually depicted, but I never fully realised to what extent. I'd definitely buy that placemat for my little nephew (or even for myself). And I quite like the colours of your "theoretical placemat", I'd even buy it like that, without names or "artistic renderings" on it!! ;-)

Firstly, I agree with previous commentators that a...

2009-08-28T17:31:10.387-07:00

Firstly, I agree with previous commentators that any depiction showing objects smaller than Mars needs to show moons as well.

Moons are interesting. After all, how many of your research-related posts this year have been about satellites of one body or another?

Secondly, you've inspired me to a more general comment on astronomical definitions:
http://lablemminglounge.blogspot.com/2009/08/new-definitions-from-international.html

Whoops that was me talking about exo and ino plane...

2009-08-28T06:37:08.121-07:00

Whoops that was me talking about exo and ino planets.

Our Solar Systemcentric definitions for exoplanets...

2009-08-28T06:35:34.624-07:00

Our Solar Systemcentric definitions for exoplanets would have been better not made but everyone was expecting one defintion offered by the IAU for both exo and ino (yeah I just coined another word candidate) planets.

This hang-up on size perplexes me. A dust mite an...

2009-08-27T08:39:37.801-07:00

This hang-up on size perplexes me. A dust mite and an apatosaur have an enormous size differential, yet both are recognized by biologists as animals. What biologist would deny that anything smaller than a hummingbird cannot be labeled an animal simply because it is too small? Or that a dust mite doesn’t “deserve” the label of animal because it isn’t as big or “important” as a brontosaur? Or that a line must be drawn somewhere because otherwise there would be too many animals? Sorry, but the logic totally escapes me.

Also, I wonder how these planet definitions will possibly survive future observations. As planet detection around other stars improves, it seems quite possible, even probable, that astronomers will find at least one Earth-size or larger body that has not cleared its orbit of debris. And what will happen if astronomers get really good at finding stuff and detected some small, icy body orbiting a red dwarf all by its lonesome? For that matter, what happens when we find some Jupiter-sized body wandering between star systems? I guess we’ll call it a “rogue planet?” So then we’ll have rogue planets, dwarf planets, ghost planets, evil planets, etc., but none of these will “really” be planets? Aye aye aye! My head is spinning like a neutron star!

The IAU never had the power to demote or promote a...

2009-08-27T02:04:19.063-07:00

The IAU never had the power to demote or promote anything. It is a matter of language. If enough people call Pluto a planet it is. A segment calls it a planet and a segment doesn't. You can't rewrite old usage so that suddenly it is wrong. I invented the slowly catching on word Exodwarf and wrote an article about Planet definition on my blog that I am fixing to allow comments. http://www.oneworldblueportals.com/bernardsstar/index.php?page=blog

So how can we get one of these placemats? Who eve...

2009-08-26T20:48:25.284-07:00

So how can we get one of these placemats? Who even makes the things?

--Greg

I'd like to see a planetary placemats of other sta...

2009-08-26T17:12:49.472-07:00

I'd like to see a planetary placemats of other star systems. Would the IAU definition of a planet still stick?

If you grew up with a placemat like this, or a wal...

2009-08-26T02:05:13.540-07:00

If you grew up with a placemat like this, or a wall poster in your third grade classroom, or a lunch box you carried every day, I now understand why you feel Pluto still deserves to be a planet.

This makes a lot of sense when understanding the reactions of taxi-drivers who implore scientists to 'reinstate Pluto'. It's less convincing (at least by itself) when trying to understand why tenured Professors of Planetary Science get so hot under the collar. I have my own theories ('IAU rules geology still more boring than astronomy' - Prague, 2006) but I'd like to hear what other people think.

Alan - wait wait wait wait! Did you look at the pi...

2009-08-25T20:19:32.478-07:00

Alan - wait wait wait wait! Did you look at the pictures? Everything orbiting the sun that is big enough to appear as large as one pixel across is there, with no human-made distinction. The only distinction is the real one between the 4 really big things, the 4 moderately big things, and all of the small things. It's not me limiting the planetary tribe to 8, it's just nature!

By the way, if length were no object in the placem...

2009-08-25T16:14:52.726-07:00

By the way, if length were no object in the placemat, I'd definitely roll this one out:

http://www.kokogiak.com/gedankengang/2007/03/all-known-bodies-in-solar-system.html

I like the idea of planetary placemats, but I thin...

2009-08-25T16:12:29.960-07:00

I like the idea of planetary placemats, but I think it would be a terrible misrepresentation to leave the asteroid belt and the Kuiper Belt objects off the mat ... almost as bad as making Pluto bigger than Mercury. That's the problem with trying to limit the planetary tribe to eight, in my humble opinion: You lose the sense of diversity in the solar system. I can imagine that even Lila (or other kids) would feel let down if they didn't see that little string of pearls in the lower right. Whether you call them the pearl planets, or dwarf planets, or ice worlds, or KBOs (which is about the least evocative label you can put on a planetary pigeonhole), I'd have to insist that "the kids stay in the picture," to paraphrase Darryl F. Zanuck.

Your post has sparked all manner of interesting th...

2009-08-25T09:24:09.492-07:00

Your post has sparked all manner of interesting thoughts, Mike, and I could probably write three or four terrifyingly large comments about different issues you've raised. Unfortunately, that might run me afoul of my rather own liberal rules on procrastination control. So I'm going to pick one.

I think one of the big reasons that Plutophiles are so attached to planethood stems from how pretty much every elementary school student comes to learn about the solar system: we think of it as a collection of planets, no more, no less.

It starts on places like Lilah's placemat and posters and lunchboxes. But open up any fourth grade science textbook--be that one from the 1950s or 1990s--and you'll see that their chapters on astronomy are laid out in pretty much the same way. You get a quick mention of the sun (if you're lucky), then consecutive sections starting with Mercury and ending with Pluto. Each kid is expected to learn one or two basic characteristics about each planet (ie, Mars = red; Jupiter = big; Saturn = rings) and learn their order from the sun. This basic arrangement of facts is repeated whenever, say, the Magic School Bus takes a trip through the solar system.

By virtue of the fact they suffer the indignity of orbiting around another world rather than the Sun, bodies like Io and Europa and Titan basically vanish altogether from a childs-eye-view solar system. Yes, those moons might eventually appear briefly in their parent planet's section in the book in seventh grade, but by then the picture is kind of set. Indeed, even our own moon gets pretty limited play in introductory astronomy, at least in the context of being a "member" of the "solar system."

But the childs-eye solar system IS the solar system of pretty much all non-astronomers. That's not to say the educated layman didn't get quite intrigued when Huygens took its plunge, but rather that this Titan place was a sort of late paste-on onto the initial mental map they had of a nine-planet solar system.

For my money, though, the Titans and Europas are far more interesting worlds to tell a nine-year-old or a ninety-year-old about than, say, Uranus and Neptune. (Aside: Does anyone anywhere ever really end up getting particularly excited by Uranus and Neptune? Oh look, the tippy-over planet that sounds dirty. Oh look, that other, um, blue one. Even in the big leagues, are there any passionate researchers out there who've devoted their lives to Neptune?)

For lack of a better term, there was a "planet-ist" bias at play when we were all taught what the solar system was. No wonder, then, that when Pluto was reclassified there were various irksome lines in the press about it getting "kicked out" or "dropped from the Solar System."

Bound up in Pluto's planethood is this fear that if it isn't in the same club as the other eight it simply won't count anymore.

It's silly, but in a world where most educated people's mental pictures of the solar system look like those placemats, it's somewhat valid. I guess the real question is what to do about it.

Yes, the eight planets will always enjoy a certain sense of top-of-mind prestige, but we really need to do more to ensure that non-planet members of the solar system get the shrift they deserve when kids learn about the solar system in the years to come. We can't expect Lilah and her schoolmates to be running around the playground rattling off some sort of Ceres-Vesta-Pallas-Hygieia singsong bit, but it would be cool if they learned about volcanoes on Io the same time they learned about gigantic cyclones on Jupiter.

I forgot Triton, but included the the Sun in my co...

2009-08-25T07:41:31.794-07:00

I forgot Triton, but included the the Sun in my count so I got 17 larger-than-pluto objects :-)

This got me thinking about planet classifications ...

2009-08-25T07:29:24.740-07:00

This got me thinking about planet classifications and I started to wonder - if we had evolved on one of the gas giants, would we consider the solar system to have 4 planets and a sun, all of which have both spherical and non-spherical moons?

SteveoR, your classification system makes the most...

2009-08-24T21:22:23.620-07:00

SteveoR, your classification system makes the most sense. If it means our solar system has hundreds of planets, what is so terrible about that?

I've seen one depiction of the worlds of our solar...

2009-08-24T19:25:52.931-07:00

I've seen one depiction of the worlds of our solar system in correct relative size. See the magazine special 'Scientific American Presents Magnificent Cosmos' from circa April 1998 (says "display until May 1998" on the cover) Page 26, 'Planetary Tour'. It shows to scale in true relative size parts of Jupiter and Saturn with Ouranos(my corrected spelling) & Neptune directly below them in full, then in order, Earth, Venus, Mars, Titan, Mercury, Ganymede, Callisto, Io, Moon, Europa, Triton, Pluto, Titania, Rhea, Oberon, Iapetus, Charon, Umbriel & Ariel.

This was before the larger TNO's had been discovered so an updated version would be interesting to see. It also includes a table & some text. I like this depiction so much I've had it colour photocopied and laminated to use as a poster.

If you'd like, I'll try scanning it & sending you a copy or you could try & track it down from the info. included.

For the record - I favour an inclusive and broad definition of 'planet' & then subdividing planets into major classes. I consider Pluto and the other ice dwarfs to be planets & there to be 3 main classes of 'planet' in our solar system, gas giants, rocky terrestrial worlds and ice dwarfs.

My preferred definition would be that a planet is :

a) Never self luminous by nuclear fusion thus not a star,

b) not directly orbiting another planet thus not a moon
&
c)large enough to be round or if rapidly spinning oblate spheroidal rounded through its own gravity thus not a comet or asteroid.