Solar system model
The enormous ratio of interplanetary distances to planetary diameters makes constructing a scale model of the solar system a challenging task. As one example, the distance between the Earth and the Sun is almost 12,000 times the diameter of the Earth. Large outdoor spaces are necessary, as are some means for highlighting smaller planets that might otherwise be invisible from a distance. For example, in the Solar System Walk model, which spans a kilometre (about 1000 yards) and represents the Earth as a peppercorn, one might tape the peppercorn to an index card to make it more visible.
Scale models in various locations
Several towns and institutions have built scale models of the solar system. The objects in such models typically do not move. See Orrery for a discussion of models whose planets do move. These can be thought of as models that are scaled in time instead of distance.
| Location | Scale | Sol dia. | Earth dia. | Sol-Earth | Sol-Pluto |
| The Real Thing | 1:1 | 1.392 Gm | 12.76 Mm | 149.6 Gm | 5.914 Tm |
| Upstate New York from Syracuse, New York | 1:46,500,000 | 25.6 m | 305 mm (1 ft) | 3.5 km | 138 km |
| University of Maine at Presque Isle | 1:93,000,000 | 15 m | 140 mm? | 1.6 km | 64 km |
| Peoria, Illinois | 1:125,000,000 | 11 m | 100 mm | 1.2 km | 64 km |
| Boston Museum of Science | 1:400,000,000 | 3.5 m | 32 mm | 376 m | 14.9 km |
| York | 1:575,872,239 | 2.417 m | 22.1 mm | 259.73 m | 10.2679 km |
| Eugene, Oregon | 1:1,000,000,000 | 1.39 m | 12 mm | 150 m | 5.9 km |
| The Sagan Planet Walk | 1:5,000,000,000 | 278 mm | 2.5 mm | 30 m | 1.18 km |
| Jodrell Bank | 1:5,000,000,000? | 30 cm? | 2.5 mm? | 30 m? | 1 km? |
| The Solar System Walk | 1:6,336,000,000 | 20.3 cm | 2 mm | 25 m | 983 m |
| Saint-Louis-du-Ha! Ha!, Quebec | 1:10,000,000,000 | 13.9 cm | 1.2 mm | 15 m | 590 m |
An imaginary model based on a classroom globe
Relating the size of the Solar system to familiar objects makes it easier for students to grasp the relative distances. Most classroom globes are 41 cm (16 inches) in diameter. If the Earth were reduced to this size, the Moon would be a 10 cm (4 inch) baseball floating 12 metres (40 feet) away. The Sun would be a beach ball 14 stories tall floating 5 kilometres (3 miles) away. Here is the solar system in that scale:
| Body | Diameter | Distance from Sun |
| Sun | 44.6 m (146 ft) | zero |
| Mercury | 15 cm (6") | 1.9 km (1.2 mi) |
| Venus | 38 cm (15") | 3.5 km (2.2 mi) |
| Earth | 41 cm (16") | 4.8 km (3.0 mi) |
| - – - – Moon, 10 cm (4"), 12 m (40 ft) from Earth | ||
| Mars | 23 cm (9") | 7.2 km (4.5 mi) |
| Jupiter | 4.55 m (179") | 24.9 km (15.5 mi) |
| Saturn | 3.81 m (150") | 45.5 km (28.3 mi) |
| Uranus | 1.63 m (64") | 92.2 km (57.3 mi) |
| Neptune | 1.55 m (61") | 144.4 km (89.7 mi) |
| Pluto | 7 cm (3") | 190 km (118 mi) |
| α Centauri A | 49.5 m (162 ft) | 1,323,500 km (822,400 mi) |
Categories: Solar system | Physics education