Solar system models, true to scale
The solar system model that doesn't lie
One scale factor for sizes and distances alike. No exaggeration mode, no inflated planets. Tell it how much room you have. It tells you honestly what fits, and what stays invisible.
The first and last sheets hang right against the wall. Distances run from sheet centre to sheet centre, hence 21.59 cm less (US Letter).
The solar system does not end at the last body you can fit. At the same scale, the rest lies here:
The nearest star. At this scale it is farther than any road you could walk. And its disc would still be bigger than every planet in your model.
Print it at true size
A4 · US Letter · CC BY 4.0One sheet per body at true physical size, plus assembly instructions with pace counts, an overview sheet and the closing card with Proxima Centauri. Generated as a PDF with explicit millimetre values, not via browser printing, which is not dimensionally reliable.
Every sheet carries a 100 mm line with millimetre marks. If it measures anything else, the printer scaled the page: set it to 100 % or ‚actual size‘ and print again. Without that check a printout looks exact and is not.
Almost all of it is nothing
All four inner planets sit inside the first five per cent of the distance. After that, almost nothing. And that is the property every classroom poster quietly removes.
Where the numbers come from
A model that does not lie is only as honest as its numbers. The values on this page come from JPL Horizons (NASA/JPL): public, checkable, each one still carrying the raw line it was taken from. What is made of them is written out next to this text, not left in a footnote: which diameter, which distance, why Proxima Centauri has to be there.
Original source: JPL Horizons at NASA/JPLFor teachers
The model does the teaching, not the text. What to decide before the lesson, and where the model's honesty ends.
Model A · the classroom, 8 m to Earth
Inside a room you can only reach the Earth: the Sun becomes a 7 cm ball, the Earth a 0.7 mm grain 8 m away. Mars would already be 12 m out, behind the door. This model ends at the Earth, and that ending is the point. What it shows is the size difference; what it cannot show is the outer system.
Model B · the schoolyard, 100 m to Neptune
Outside you can reach Neptune, and the emptiness becomes the lesson. Mark the Sun, call the far end Neptune, and let everyone place a marker where they think the Earth is. Then walk it: the Earth sits at 3.3 m of 100, and all four inner planets fit in the first five metres. The price of this model: at 0.28 mm the Earth is too small to show.
Why textbooks teach the opposite
Every printed solar system is squeezed, usually by a factor of a hundred or more, because the page has an edge. The misconception is not a gap in knowledge, it is what the picture shows. Put a textbook page next to the walked model and the difference does the teaching.
Where this model stops being honest
It is a snapshot along a line: the planets are never in a row, the orbits are ellipses, and no room exists in which the Sun and Neptune are both visible at true scale. Saying that out loud is part of the lesson: a model whose limits stay unnamed teaches the next wrong picture.
Ten minutes of preparation
Print the sheets, then measure the 100 mm line with a ruler. Printers rescale silently, and a wrong printout quietly undoes the whole point. Bring a tape measure or count paces (about 0.75 m), plus chalk or tape for the markers. That is all.
The number that stays
In the 100 m model the nearest star is 893 km away, beyond any yard, any city. Everything else on this page is a diagram; this one number is why the model matters.
To picture it
Numbers this large stop meaning anything. These comparisons put them back into everyday terms.
By airliner to the Moon
An airliner at cruising speed (900 km/h) would need a good two and a half weeks for the 384,400 km to the Moon, without landing. Light covers it in 1.3 seconds.
By airliner to the Sun
The 149,598,261 km to the Sun make almost two decades of flight. By car (100 km/h) it would be 171 years.
Every planet fits in the Moon gap
Line up the seven other planets like beads and their diameters add to 380,020 km. The gap between Earth and Moon is 384,400 km. They all fit, with 4,380 km to spare.
Too fast to see the ISS
If you were out in space and the ISS shot past close by, you would not see it. It is simply too fast. At 27,605 km/h it covers 767 metres in a blink, and its whole length passes you in 14 milliseconds, quicker than the eye can follow. From the ground you do see it: there it is 408 km away, and anything far away looks slow.
Source: International Space Station
Why rockets do not fly upwards
Getting to space is the easy part: lifting to 408 km costs only 11 % of the energy. The other 89 % goes into speed. That is why no rocket climbs straight out; it tips over and accelerates along the Earth until it reaches 27,605 km/h. Only then does it stop falling back and starts falling past the Earth instead.
A collision without collisions
The Milky Way and Andromeda are heading towards each other. Whether they actually meet has been open since 2025: Hubble and Gaia data give roughly a 50:50 chance within the next ten billion years, and only two per cent for the four to five billion years once quoted. And if it happens, virtually no star will hit another: there is so much space between them that the galaxies pass through one another without touching.
Source: Andromeda–Milky Way collision
One drop against every beach
A single drop of water (0.05 ml) holds about 1.7 sextillion molecules. The whole Earth has an estimated 7.5 quintillion grains of sand, every beach and desert together. So that one drop contains roughly 223 times more molecules than there are grains of sand. Stars in the observable universe: an estimated 10 to 1,000 sextillion. So 30 ml of water — about 2 tablespoons — holds more molecules than there are stars in the observable universe.
A star that swallows Saturn
The red supergiant Stephenson 2-18 is the largest star known so far. Its radius is estimated at 2,158 times the Sun's, or 1.5 billion km. Put it where our Sun is and its surface would lie beyond Saturn's orbit (1.43 billion km). About 10 billion Suns would fit inside it — and 1.3 million Earths inside the Sun.
Source: Stephenson 2-18
A hole bigger than the solar system
The quasar TON 618 hosts one of the most massive black holes known. Just how massive is disputed: the older estimate gives 66 billion solar masses, a newer one about 40 billion. That puts the event horizon between 236 and 390 billion km across — 66 times the distance from the Sun to Pluto. Our entire planetary system would vanish inside it without touching the edge.
Source: TON 618
Travel times are deliberately naive: distance ÷ cruising speed, straight ahead, no stops, no orbital mechanics. Not a mission plan, but a yardstick for everyday experience.