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A walk from the Sun to Neptune

Almost every picture of the solar system is wrong about scale. Walk it at true scale and feel how empty space really is.

10 분

NASA

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스케일 워크

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Everything here is at true scale: sizes and distances in the same proportion. Each pixel you scroll carries you 3,000 km.

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수성 4,879 km · 0.387 au · 3분 13초
금성 12,104 km · 0.723 au · 6분 1초
지구 12,742 km · 1 au · 8분 19초
화성 6,779 km · 1.52 au · 12분 40초
세레스 939 km · 2.77 au · 23분 0초
목성 139,822 km · 5.2 au · 43분 16초
토성 116,464 km · 9.54 au · 1시간 19분
천왕성 50,724 km · 19.2 au · 2시간 40분
해왕성 49,244 km · 30.1 au · 4시간 10분
명왕성 2,377 km · 39.6 au · 5시간 29분

Keep scrolling. Every picture you have seen of the solar system squeezed this emptiness out.

Mercury is ahead, where sunlight is almost seven times stronger than on Earth.

Still nothing. You have crossed 1680만 km since 수성.

The sunlight passing you now left the Sun 5분 5초 ago.

Earth is ahead. Watch how small home turns out to be.

화성 is still 5880만 km ahead.

A radio message from Earth takes between 3 and 22 minutes to reach Mars, depending on where the two planets are.

You could line up 4,611 Earths side by side in the space you have crossed since 지구.

You are 14% of the way from 화성 to 세레스.

Still nothing. You have crossed 5310만 km since 화성.

The sunlight passing you now left the Sun 17분 6초 ago.

세레스 is still 7960만 km ahead.

You are inside the asteroid belt. Did you hit anything? On average the asteroids are about a million kilometres apart.

You could line up 12,497 Earths side by side in the space you have crossed since 화성.

You are 17% of the way from 세레스 to 목성.

Still nothing. You have crossed 1.22억 km since 세레스.

The sunlight passing you now left the Sun 33분 8초 ago.

목성 is still 1.22억 km ahead.

You could line up 23,846 Earths side by side in the space you have crossed since 세레스.

You are 10% of the way from 목성 to 토성.

Still nothing. You have crossed 1.3억 km since 목성.

The sunlight passing you now left the Sun 54분 5초 ago.

토성 is still 3.89억 km ahead.

Voyager 1 took about 20 months to fly from Jupiter to Saturn.

You could line up 30,529 Earths side by side in the space you have crossed since 목성.

You are 70% of the way from 목성 to 토성.

Still nothing. You have crossed 5.19억 km since 목성.

The sunlight passing you now left the Sun 1시간 16분 ago.

천왕성 is still 13.1억 km ahead.

You could line up 20,605 Earths side by side in the space you have crossed since 토성.

You are 27% of the way from 토성 to 천왕성.

Still nothing. You have crossed 5.25억 km since 토성.

Uranus orbits twice as far from the Sun as Saturn. The farther out you go, the emptier it gets.

The sunlight passing you now left the Sun 2시간 3분 ago.

천왕성 is still 5.25억 km ahead.

You could line up 82,418 Earths side by side in the space you have crossed since 토성.

You are 82% of the way from 토성 to 천왕성.

Still nothing. You have crossed 13.1억 km since 토성.

The sunlight passing you now left the Sun 2시간 48분 ago.

해왕성 is still 13.3억 km ahead.

You could line up 34,840 Earths side by side in the space you have crossed since 천왕성.

You are 36% of the way from 천왕성 to 해왕성.

Still nothing. You have crossed 7.4억 km since 천왕성.

Voyager 2 needed about three and a half years to cross this gap, from Uranus in 1986 to Neptune in 1989.

The sunlight passing you now left the Sun 3시간 37분 ago.

해왕성 is still 4.44억 km ahead.

You could line up 104,519 Earths side by side in the space you have crossed since 천왕성.

You are 91% of the way from 천왕성 to 해왕성.

Still nothing. You have crossed 1.29억 km since 해왕성.

The sunlight passing you now left the Sun 4시간 24분 ago.

The Kuiper belt: a ring of icy worlds so spread out that after Pluto, New Horizons flew close to just one of them.

명왕성 is still 9.06억 km ahead.

You could line up 50,798 Earths side by side in the space you have crossed since 해왕성.

You are 55% of the way from 해왕성 to 명왕성.

Still nothing. You have crossed 9.06억 km since 해왕성.

New Horizons, one of the fastest spacecraft ever launched, took nine and a half years to reach Pluto. Sunlight gets to Pluto's average distance in about five and a half hours.

The sunlight passing you now left the Sun 5시간 15분 ago.

명왕성 is still 1.29억 km ahead.

0 km 0 au · 빛은 여행을 했어요 0 s
Autopilot speed

데이터 테이블 (텍스트 대체)
세계지름태양으로부터의 거리태양으로부터의 거리px
수성4,879 km0.387 au3분 13초19,303
금성12,104 km0.723 au6분 1초36,070
지구12,742 km1 au8분 19초49,866
화성6,779 km1.52 au12분 40초75,981
세레스939 km2.77 au23분 0초137,907
목성139,822 km5.2 au43분 16초259,447
토성116,464 km9.54 au1시간 19분475,555
천왕성50,724 km19.2 au2시간 40분956,886
해왕성49,244 km30.1 au4시간 10분1,499,465
명왕성2,377 km39.6 au5시간 29분1,974,125

Almost every picture of the solar system lies. To fit on a page, the planets are squeezed together and blown up in size. Walk it at true scale and you discover the real star of the show: empty space.

A thin crescent of Neptune against black space.
Neptune, the farthest planet, seen by Voyager 2 as it left for interstellar space. Credit: NASA/JPL

The solar system is mostly empty space, and that emptiness is the whole story.

Look

Most pictures of the solar system squeeze the planets together like beads on a string, and draw them far too big. They have to: at true scale, a page would be almost completely empty.

Guess first: if the Sun were a beach ball, how far away would Earth be? A step? A room? A street?

A street. With the Sun as a 1-metre ball, Earth is a 9 mm pea about 107 metres away: roughly the length of a football pitch. Keep that picture in mind as you travel.

The Scale Walk above is drawn at true scale: sizes and distances in the same proportion. Every pixel you scroll carries you 3,000 km. Scroll inside the frame, press Next world, or tap a planet on the journey map at the top.

  • The journey map is to scale too. The white marker is you. Notice how the Sun and the four inner planets crowd together at the far left.
  • The odometer counts kilometres and the time sunlight has needed to get where you are.
  • When you stop near a world, the camera locks on and leans in (the zoom is shown next to the scale bar), and a card tells you where you are.
  • Earth, a globe 12,742 km across, is almost 50,000 scrolled pixels from the Sun. Neptune is about 1.5 million pixels away.

Notice how much of the trip is just black, with only a few lines of narration drifting past. That is the real solar system: tiny worlds separated by enormous emptiness.

Understand

A scale model divides every length by the same number. Here the number is 3,000: 3,000 km of real space becomes 1 pixel.

WorldReal diameterDiameter at 1 px = 3,000 kmDistance from SunAt this scale
Sun1,391,400 km464 px00
Earth12,742 km4 px149.6 million km49,866 px
Jupiter139,822 km47 px778.3 million km259,437 px
Neptune49,244 km16 px4,498 million km1,499,000 px

A handy comparison uses the Sun as a 1-metre ball. Divide everything by the Sun’s diameter (1.39 million km):

  • Earth is a 9 mm pea, 107 m away.
  • Jupiter is a 10 cm grapefruit, 560 m away.
  • Neptune is a 3.5 cm marble, 3.2 km away.
  • The nearest star, Proxima Centauri, would be another ball about 29,000 km away: more than two thirds of the way around the real Earth.

Try the autopilot at 1×, the real speed of light. You move 100 pixels per second, which feels slow on screen. Real sunlight really does need 8 minutes to reach Earth and more than 4 hours to reach Neptune. The faster settings compress time, not distance: the autopilot still brakes and pauses at every world.

Guess first: scrolling with a mouse wheel, are you moving faster or slower than light?

Much faster. A brisk scroll carries you millions of kilometres per second, often ten or more times the speed of light; the speed readout under the odometer shows it. Even so, the outer planets take a long time to reach. That is how big the distances are.

Master

Two separate compressions distort normal diagrams: the size scale and the distance scale. The ratio of the Sun-Neptune distance (4.5 × 10⁹ km) to Earth’s diameter (1.27 × 10⁴ km) is about 350,000. A screen 1,000 pixels tall can resolve a range of about 1,000, so no single static image can show both the planets and their spacing. Interactive zoom, logarithmic axes or a scroll-length model like this one are the only honest options.

This is also why the orrery on this site offers two modes. Readable scale compresses distance with a square root (r_screen ∝ √r) and draws planets at fixed legible sizes. True scale is linear in both size and distance, so the planets shrink to sub-pixel dots.

The emptiness has consequences for spaceflight. Travelling between planets is not like driving between cities: the planets move, the distances are huge, and the energy cost depends far more on changes of speed than on distance. That idea, delta-v, is at the heart of the Navigator path.

A last scale fact: the asteroid belt, often drawn as a crowded field of rocks, is so sparse that spacecraft cross it without any special manoeuvres. The Kuiper belt beyond Neptune is emptier still.

한번 해보세요

Set the autopilot speed to 1× and press 'Travel at the speed of light'. Watch the light-time clock as you reach Earth: about 8 minutes 20 seconds. Before you look at the table, guess how long the same trip takes to Neptune, then check.

빠른 퀴즈

3 quick questions. Pick an answer to see if you are right.

  1. If the Sun were a ball 1 metre wide, about how big would Earth be?

    1. A A football
    2. B A grapefruit
    3. C About 9 millimetres, like a pea
    4. D About 1 millimetre
    Show the answer

    C. About 9 millimetres, like a pea The Sun is about 109 times wider than Earth, so 1 m ÷ 109 ≈ 9 mm.

  2. At that same scale, how far away would Earth be from the 1-metre Sun?

    1. A About 1 metre
    2. B About 10 metres
    3. C About 107 metres
    4. D About 1 kilometre
    Show the answer

    C. About 107 metres 1 au is about 107.5 Sun diameters, so Earth would be a pea about the length of a football pitch away.

  3. Why do most drawings of the solar system show the planets close together?

    1. A Because they really are close
    2. B Because at true scale the planets would be too small to see on the page
    3. C Because the drawings show the planets at their closest approach
    4. D Because of light pollution
    Show the answer

    B. Because at true scale the planets would be too small to see on the page

Finish line

  • Played with the interactive
  • Read the lesson
  • Did the challenge
  • Took the quiz

Mark the lesson complete to save it to your progress on this device.

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