Because The Sun’s too big, right? I think I picked this up years ago at The Exploratorium in San Francisco. Excellent place to take the kiddies, BTW.
So, if Pluto were the size of a pea, The Sun would be the size of a ?
By what measure? I dunno, take your pick.
Peace,
mangeorge
BTW; I understand that the distances are also way too large.
About 3.6 meters, assuming a pea is 6 mm.
How about this? Scale Model of the Solar System, Peoria, Illinois
“When we visited, we learned too late that the barbershop housing Venus was closed Sundays and Mondays.”
I need to write a song around that.
Eugene Oregon had one I think. I found Earth and Mars at Alton Baker Park but that was all I ever saw of it.
Eugene still has it. You can see it by following along the river trail away from downtownish (near Skinner’s Butte, if memory serves) towards the Valley River Center. It gives a good perspective, for sure! (The inner system is relatively close, but then everything gets spread way the heck apart!)
Ah! So it’s distance, rather that size, that keeps the model from fitting in my basement.
I haven’t seen one of those models as in the link, but I have seen The World’s Largest Catsup Bottle. 
In person
There’s a Solar System model right here in Boston. They used to have Neptune at the mall near my house, but it got taken away. God knows where Neptune is now.
They’ve also got one laid out along the lampposts on the Mall in Washington, D.C.
One that doesn’t seem to be listed in the previous link is the model that starts at the Smithsonian’s National Air and Space Museum on the National Mall in Washington DC.
Here’s the current link for that: Voyage Scale Model of the Solar System
Shouldn’t this whole task be a lot easier now that Pluto has been demoted?
The biggest one is in Stockholm.
The sun is the 110 m diameter Globen arena and Pluto is 12 cm and 300 kilometres away.
Sigh. This is going to cause peturbations that are going to require all the other orbits to be recalculated.
Dammit, now the whole thing’s out of whack!
There’s also a scale model online here. Be warned, it requires a bit of scrolling…
EDIT: Though it’s not to scale in relative size, only in distance.
There’s no reason they have to exclude non-planets from the models. Including the dwarf planets (Ceres, Pluto, Eris, Makemake) and other objects (Halley’s Comet, other large asteroids and TNOs, centaurs, and the larger moons) should make for a richer model.
I think we should make a model covering the entire USA. The Sun would have to be in New York, of course, since it’s already the center of the universe. A scale of about 100 Km to 1 AU would be about right. The main problem would be finding an object in New York the right size (about 932 meters in diameter – Donald Trump’s ego is probably too large) to represent the Sun. Other objects could be in various cities. For example
Mercury - White Plains NY
Venus - Princeton NJ
Earth - New Haven
Mars - Philadelphia
Vesta - Harrisburg or Providence
Ceres - Baltimore
Pallas - Boston
Hygiea (4th largest asteroid) - Washington
Jupiter - Pittsburgh
Saturn - Columbia SC, Cincinnati, Lexington KY, or Asheville NC
Chiron - Chicago, St Louis, Minneapolis, or numerous other cities
Uranus - Baton Rouge or Topeka
Neptune - Great Falls MT
Pluto - Flagstaff
Eris - Los Angeles
Sedna - Honolulu
Note that I didn’t restrict the locations to cities at exactly the semi-major axis, but any city between the perihelion and aphelion was allowed. For instance, Philly is about at Mars’s perihelion.
Other TNOs could probably be fit in at other cities on the west coast. Halley’s Comet could go just about anywhere except for the area around New York. We could auction it off.
So anyone up for doing this?
I’ve always thought these scale models of the solar system are a bit crap because they don’t actually move! I want my 12cm Pluto to be orbiting 300km away, damn it! It might take a bit of logistical planning, and people might have to duck every so often, but how cool would it be? 
The model on the mall in DC is fascinating.
There used to be one painted on the sidewalk in Berkeley–it started next to an elementary school and ended near the UC campus. I walked to class along that street for a long time and every once in a while I would discover a new planet! It was old and faded then, you see, and you couldn’t see all the planets any more (I never did find Pluto), and it was really easy to walk over the planets without seeing them, especially Neptune which was right under a bunch of olive trees or something.
Those are not on lampposts, but are mounted in their own little “obelisks” that sort of resemble parking meters from the Jetsons. (To my eye anyway.) There’s a picture of one of them here.
