The Peppercorn Model of the Solar System

The Peppercorn Model, also known as the Thousand Yard Model, is a scale model of the solar system which shows the relative sizes of the planets and the distances between them at the same time using the same linear scale.

At this scale the Sun is about the size of a soccer ball, the Earth is about the size of a peppercorn, and Pluto is a grain of salt about 1000 yards from the Sun.

As you walk among the planets you will not just see but also feel the vast emptiness of space even in our own solar system.

Solar System Object	Model Object and Diameter		Distance^† (in AU)	Added Distance	Total Distance
	Object	inches	mm	AU	yards	meters	yards	meters
Sun	a soccer ball	8.7''	22 cm	0.00			0 yd	0 m
Mercury	a pin head	0.030''	0.8 mm	0.39	+10 yd	+9 m	10 yd	9 m
Venus	a peppercorn	0.075''	1.9 mm	0.72	+9 yd	+8 m	19 yd	17 m
Earth	a peppercorn	0.079''	2.0 mm	1.00	+7 yd	+7 m	26 yd	24 m
Mars	a pin head	0.042''	1.1 mm	1.52	+14 yd	+12 m	39 yd	36 m
^*Ceres	half a grain of salt	0.006''	0.15 mm	2.77	+32 yd	+29 m	72 yd	65 m
Jupiter	a walnut, or chestnut	0.89''	23 mm	5.20	+63 yd	+57 m	134 yd	123 m
Saturn	an acorn or hazelnut	0.75''	19 mm	9.58	+113 yd	+103 m	247 yd	226 m
Uranus	a coffee bean	0.318''	8 mm	19.2	+249 yd	+228 m	497 yd	454 m
Neptune	a coffee bean	0.308''	8 mm	30.1	+281 yd	+257 m	777 yd	711 m
^*Pluto	a grain of salt	0.015''	0.38 mm	35.1^† ↑	+129 yd	+118 m	906 yd	829 m
^*Quaoar	a grain of salt	0.007''	0.17 mm	42.7^†	+196 yd	+179 m	1102 yd	1008 m
^*Haumea	a grain of salt	0.010''	0.25 mm	49.9^† ↓	+187 yd	+171 m	1290 yd	1179 m
^*Makemake	a grain of salt	0.009''	0.23 mm	52.7^† ↑	+71 yd	+65 m	1360 yd	1244 m
^*Eris	a grain of salt	0.014''	0.37 mm	95.6^† ↓	+1109 yd	+1014 m	2470 yd	2258 m
^*dwarf planets	Model Object	Diameter	Distance (in AU) ^† semi-major axis	Added Distance	Total Distance

Scale: 1 inch = 100,000 miles -- On this scale the next nearest star, Proxima Centauri, would be about 4,000 miles away!

1 AU = 1 Astronomical Unit = average (mean) distance between the Earth and the Sun
1 AU = 1.4960 × 10¹¹ meters = 9.2956 × 10⁷ miles
^† The orbits of the planets are elipses. The distances reported for the major planets are the semi-major axis of the orbit. The distances for the dwarf planets are the actual distance from the Sun at some recent time and will be updated occasionally. The arrows ↑ and ↓ indicate whether the object's distance from the sun is currently increasing or decreasing.

Sites

It is possible to set up or walk the model almost anywhere that you can walk for a thousand yards (or meters). It does not have to be in a straight line, since the goal is to show you the sizes of the planets compared to the sizes of the orbits. If you do set it up in a straight line (as on a long bridge or trail) you should remind everyone that the planets never line up all in one line.

That said, here are some locations where the model has been set up with success, including maps to show where the planet stations can be placed.

Walkway over the Hudson between Poughkeepsie and Highland, NY
SUNY College at New Paltz , New York
U.S. Military Academy West Point, NY
Marist College Poughkeepsie, NY
Dutchess County Rail Trail at Morgan Lake Poughkeepsie, New York
Ulster County Fairgrounds New Paltz, NY
Riverfront City Park Salem, Oregon

Resources

The Peppercorn Model of the Solar System: A presentation by Eric Myers for the joint meeting of the New York, New Jersey, and New England sections of the American Association of Physics Teachers, held at Marist College on Sept. 28th 2013.
Solar System Mystery Walk: The main idea of the Solar System Mystery Walk is that a group will travel through a scale model of the solar system marked out using the conventional symbols for the planets, which most people don't recognize. When you arrive at a new planet, whoever in the group is carrying the envelope marked with that symbol opens it up to reveal the name of the planet and share some facts about it.

Other Scale Models

The 1000 yard model or Peppercorn Model is not the only scale model of the solar system, though it does have the distinct advantage of illustrating the relative scales of the planets and their orbits using everyday objects. Models at other scales can do the same thing, though there has to be some balance: of the model is too small in distance, the planets will be too small to see; if the planets are larger then the distances may be too large to travel comfortably.

That said, here are some other scale models of the solar system that use the same scale for the sizes of the planets and the sizes of their orbits.

Sagan Planet Walk in downtown Ithaca, New York
Voyage Model Solar System on the Capital Mall in Washington, D.C.
Other solar system models (from Wikipedia)
SOLAR SYSTEM Passport to the Planets - A Scale Model of the Solar System - Student activity for 4th, 5th, and 6th grade students
Scales of the Universe - relative sizes of all things large and small
If the Moon were only one Pixel - a tediously accurate scale model of the solar system
To Scale: The Solar System - On a dry lakebed in Nevada, a group of friends build the first scale model of the solar system with complete planetary orbits
Lightspeed Model of the Solar System - an alternative model of the solar system where the planets are arranged by the time it takes light from the Sun to reach them.

References

The Thousand-Yard Model or, the Earth as a Peppercorn by Guy Ottewell
The Thousand-Yard Model or, The Earth as a Peppercorn from NOIRLab - the National Optical-Infrared Astronomy Research Laboratory (previously hosted by NOAO - the National Optical Astronomy Observaotry).