Example Data Table
| Scale |
Model Sun |
Earth diameter |
Earth distance |
Good use |
| 1:1,000,000,000 |
1.393 m |
12.742 mm |
149.6 m |
Outdoor walk |
| 1:5,000,000,000 |
27.854 cm |
2.548 mm |
29.92 m |
School hall |
| 1:10,000,000,000 |
13.927 cm |
1.274 mm |
14.96 m |
Classroom wall |
Formula Used
Scale ratio from model Sun: ratio = real Sun diameter / model Sun diameter.
Model diameter: model diameter = real diameter / ratio.
Model distance: model distance = real mean orbital distance / ratio.
Clear gap: clear gap = center distance - Sun model radius - planet model radius.
Wire estimate: wire estimate = spacing from previous body x wire slack factor.
Light delay: light minutes = real distance / 299,792.458 / 60.
LED current: total current = LED count x LED current.
Resistor: resistor = (supply voltage - LED voltage) / LED current.
How to Use This Calculator
Choose a scale ratio or enter a model Sun diameter.
Select the output unit that matches your build space.
Enter a starting offset when the model begins after a sign.
Set a wire slack factor for curves and service loops.
Add LED details when your display needs lighting estimates.
Press Submit. Results appear above the form and below the header.
Use CSV for spreadsheet planning. Use PDF for build notes.
Scale Model Planning
A scale solar system turns huge astronomy values into useful shop measurements. The Sun, planets, and orbital distances shrink by one shared ratio. That ratio keeps every part proportional. It also makes layout errors easier to see before cutting boards, printing labels, or installing display lights.
Why Scale Matters
Real planetary distances are not evenly spaced. Mercury stays close to the Sun. Neptune sits far away. A model that scales diameter only can look neat, but it hides distance. A model that scales distance only can leave tiny planets. This calculator shows both values together. You can decide whether the display should be accurate, compact, or balanced for teaching.
Electrical Display Use
Many solar system displays include small lamps or LEDs. The calculator includes simple electrical estimates for a lit model. It can total the current for parallel LEDs. It can estimate power from the selected supply voltage. It can also suggest one resistor value for each LED branch. These values are planning aids. Always check final wiring, heat, polarity, and safe supply limits before building.
Layout Decisions
The center distance shows where each planet center should be placed from the Sun center. The clear gap subtracts the Sun radius and the planet radius. That helps when objects are mounted on a rail, wall, or long cable. The starting offset lets you move the whole model away from an edge. The wire slack factor helps estimate extra cable for bends, connectors, service loops, and neat routing.
Practical Accuracy
Solar system values are rounded, because planets have changing orbital positions. Mean orbital distance is best for classroom scale work. It gives a stable layout that is easy to repeat. Diameter values are also rounded for readable output. Very small model planets may be hard to build. In that case, keep distances scaled, but set a minimum visible planet size. Explain that choice on the display label.
Best Results
Start with the space you have. Then test several ratios. A one to one billion model is large, but very clear. Smaller ratios fit indoors. Export the results to CSV for spreadsheets. Use the PDF option for quick build notes. Keep a copy beside the display plan and wiring guide.
FAQs
What does the scale ratio mean?
A ratio of 1:1,000,000,000 means one model unit equals one billion real units. Every diameter and distance uses the same shrink factor.
Should I scale planet sizes and distances together?
Yes, for strict accuracy. Some displays enlarge planets for visibility. When you do that, label the model clearly so viewers understand the change.
Why are mean orbital distances used?
Planet distances change during orbit. Mean distance gives one stable value. It works well for teaching models, signs, and permanent display layouts.
Can this calculator include Pluto?
Yes. Use the Pluto option when you want a longer historical or dwarf planet display. It will add Pluto to the output table.
What is clear gap distance?
Clear gap is open space between the Sun surface and planet surface. It helps when planning physical clearance on rails, wires, or walls.
What does wire slack factor do?
It adds extra cable allowance. A factor of 1.10 adds ten percent for bends, connectors, routing, repairs, and safer installation handling.
Is the LED resistor value final?
No. It is a planning estimate for one branch. Check your LED data sheet, supply rating, heat, polarity, and wiring method before assembly.
Why are tiny planets hard to build?
At small scales, rocky planets can become pin sized. Use larger marker beads or labels when strict scale sizes are too small to handle.