Sizes are rounded values from the sources listed under each object. Drawings are schematic and are not photographs: Earth’s coastlines come from Natural Earth map data (public domain); its colours, clouds and lights, and the surfaces of the Moon, planets and galaxies, are generated in code. Objects are laid out side by side at one common scale: the one in the middle is the one you are zoomed in on, and bigger neighbours run off to the right.
Light is fast but not instant. When you look at a star you see light that left it years ago, so a star that is as many light-years away as you are years old is showing you light that set off the year you were born.
Where are you, really? Type your town and country and get your full cosmic address, from your street out to the edge of the observable universe, as a picture you can save or share.
Nothing you type leaves this page: the card is drawn in your browser.
Build a scale model of the Solar System on your playground or street. Put a ball for the Sun at the start, then walk: the table tells you where each planet goes and how small it is. On a phone you can also let the GPS tell you which planet you have reached.
GPS works outdoors on a phone and is accurate to about 5–10 m, so use a big scale (football or larger). Your location is only used on this device.
?focus=cell).You are about 1.7 metres tall. A cricket ball is about 7 centimetres across, a honey bee about 1.3 cm, the width of a human hair about 0.07 mm. Going up, a blue whale is 25 m long, the tallest tree is about 116 m, and Mount Everest rises 8,849 m. Each of these can be pictured. The trouble starts when we go a lot further: Earth is 12,742 km across, the Sun is 109 times wider than that, and the nearest star is 4.25 light-years away. The numbers get too big to feel, so scientists compare sizes by asking how many times bigger.
Write every length as 10 to some power: 1 m is 10⁰, 1 km is 10³, 1 mm is 10⁻³. Each time the power goes up by one, the length is ten times bigger. A hydrogen atom is about 10⁻¹⁰ m and a person about 10⁰ m, so a person is about ten billion times bigger than an atom: ten powers of ten. To compare two things you only have to subtract their powers.
If you zoom from a hydrogen atom to its nucleus you cross a factor of about 63,000, and there is nothing between them but the electron cloud. In the same way, the Sun is 1.4 million km wide but its nearest neighbour is 40 trillion km away: about 29 million Sun-widths. Matter in the universe is gathered in tiny, dense specks (nuclei, planets, stars) separated by enormous gaps. That is why the picture slides past long stretches with little in them.
The tool plots log₁₀ of each size, so equal steps on the ruler under the picture are equal ratios, not equal lengths. The picture itself uses one true scale at a time: all objects are drawn at the same metres-per-pixel, side by side, so the ones next to the one you are zoomed in on are shown at their real relative sizes. Light travels at c = 299,792,458 m/s, so any size can also be given as a light-crossing time t = d/c, and a light-year (9.46×10¹⁵ m) is just the distance light covers in one year. For the observable universe the crossing time is not a real travel time, because space expands while the light is on its way.
Worked example. How many carbon atoms (diameter 1.54×10⁻¹⁰ m) would stretch across a human hair (7×10⁻⁵ m)? 7×10⁻⁵ ÷ 1.54×10⁻¹⁰ = 4.5×10⁵, about 450,000.
Beyond this scale. The simulation stops at the quark limit (10⁻¹⁸ m) because nothing smaller has been measured. The Planck length, 1.6×10⁻³⁵ m, is a theoretical scale; it is 17 more powers of ten down.
| Object | Size | log₁₀(m) | Light crosses in | What is measured |
|---|---|---|---|---|
| Quarks & electrons | < 10⁻¹⁸ m | ≤ −18 | — | upper limit on size |
| Proton | 1.7 fm | −14.77 | 5.6 × 10⁻²⁴ s | diameter (2 × charge radius) |
| Helium-4 nucleus (alpha particle) | 3.4 fm | −14.47 | 1.1 × 10⁻²³ s | diameter (2 × rms charge radius) |
| Carbon-12 nucleus | 4.9 fm | −14.31 | 1.6 × 10⁻²³ s | diameter (2 × rms charge radius) |
| Uranium-238 nucleus | 11.7 fm | −13.93 | 3.9 × 10⁻²³ s | diameter (2 × rms charge radius) |
| Hydrogen atom | 106 pm | −9.98 | 3.5 × 10⁻¹⁹ s | diameter (2 × Bohr radius) |
| Carbon atom | 154 pm | −9.81 | 5.1 × 10⁻¹⁹ s | diameter (2 × covalent radius) |
| Water molecule | 280 pm | −9.55 | 9.3 × 10⁻¹⁹ s | approximate diameter |
| DNA double helix | 2 nm | −8.70 | 6.7 × 10⁻¹⁸ s | width of the helix |
| Hemoglobin molecule | 5.5 nm | −8.26 | 1.8 × 10⁻¹⁷ s | approximate width |
| Ribosome | 25 nm | −7.60 | 8.3 × 10⁻¹⁷ s | approximate diameter |
| Coronavirus particle | 100 nm | −7.00 | 3.3 × 10⁻¹⁶ s | approximate diameter |
| E. coli bacterium | 2 µm | −5.70 | 6.7 × 10⁻¹⁵ s | length |
| Red blood cell | 7.5 µm | −5.12 | 2.5 × 10⁻¹⁴ s | diameter |
| Typical human cell | 20 µm | −4.70 | 6.7 × 10⁻¹⁴ s | typical diameter |
| Human hair (thickness) | 70 µm | −4.15 | 2.3 × 10⁻¹³ s | thickness |
| Paramecium | 200 µm | −3.70 | 6.7 × 10⁻¹³ s | length |
| Honey bee | 1.3 cm | −1.89 | 4.3 × 10⁻¹¹ s | body length |
| Cricket ball | 7.2 cm | −1.14 | 2.4 × 10⁻¹⁰ s | diameter |
| Human (adult) | 1.7 m | 0.23 | 5.7 × 10⁻⁹ s | height |
| Blue whale | 25 m | 1.40 | 8.3 × 10⁻⁸ s | length |
| Tallest tree | 116 m | 2.06 | 3.9 × 10⁻⁷ s | height |
| Burj Khalifa | 828 m | 2.92 | 2.8 × 10⁻⁶ s | height |
| Mount Everest | 8,849 m | 3.95 | 3 × 10⁻⁵ s | height above sea level |
| Neutron star | 23 km | 4.36 | 7.7 × 10⁻⁵ s | approximate diameter |
| Himalayan mountain range | 2,400 km | 6.38 | 0.008 s | length |
| The Moon | 3,475 km | 6.54 | 0.012 s | diameter |
| White dwarf (Sirius B) | 11,700 km | 7.07 | 0.039 s | approximate diameter |
| Earth | 12,742 km | 7.11 | 0.043 s | mean diameter |
| Jupiter | 143,000 km | 8.16 | 0.48 s | equatorial diameter |
| Moon’s orbit | 769,000 km | 8.89 | 2.6 s | width of the orbit (2 × mean distance) |
| The Sun | 1.39 million km | 9.14 | 4.6 s | diameter |
| Sagittarius A* (black hole) | 25 million km | 10.40 | 1.4 min | diameter of the event horizon |
| Earth’s orbit | 2 AU | 11.48 | 16.6 min | width of the orbit (2 AU) |
| Betelgeuse | 6.7 AU | 12.00 | 55.6 min | approximate diameter |
| Solar System (to Neptune’s orbit) | 60.2 AU | 12.95 | 8.3 hours | width of Neptune’s orbit |
| Heliosphere | 240 AU | 13.56 | 1.4 days | approximate width (Voyager 1 left it at 121 AU) |
| M87* (black hole) | 250 AU | 13.58 | 1.5 days | diameter of the event horizon |
| Oort Cloud (hypothetical) | 3.2 light-years | 16.48 | 3.2 years | approximate outer width |
| Sun → Proxima Centauri | 4.2 light-years | 16.60 | 4.2 years | distance between the two stars |
| Orion Nebula | 24.3 light-years | 17.36 | 24.3 years | width of the glowing cloud |
| Sun → centre of the Galaxy | 26,000 light-years | 20.40 | 26,000 years | distance |
| Milky Way galaxy | 100,000 light-years | 20.98 | 100,000 years | approximate width of the disk |
| Andromeda Galaxy (M31) | 220,000 light-years | 21.32 | 220,000 years | approximate width of the disk |
| Milky Way → Andromeda | 2.5 million light-years | 22.38 | 2.5 million years | distance between the two galaxies |
| Local Group | 10 million light-years | 22.98 | 10 million years | approximate width |
| Virgo Supercluster | 110 million light-years | 24.02 | 110 million years | approximate width |
| Laniakea Supercluster | 520 million light-years | 24.69 | 518 million years | approximate width |
| Sloan Great Wall | 1.4 billion light-years | 25.11 | 1.4 billion years | approximate length |
| Observable universe | 93 billion light-years | 26.94 | 93 billion years | diameter |
This page can be embedded in a learning platform or class website. Use Simple for grades 6–9 and Advanced for grades 10–12 and intro university courses.
The observable universe is about 93 billion light-years across (about 8.8×10²⁶ m). Light has had only 13.8 billion years to arrive, yet the radius is about 46.5 billion light-years, because space has kept expanding while the light travelled. Beyond it there may be more universe, but its light has not had time to reach us.
Nobody knows. Quarks and electrons behave like points: experiments show they are smaller than about 10⁻¹⁸ m, and no size has ever been measured. The Planck length, about 1.6×10⁻³⁵ m, is a theoretical scale where quantum gravity is expected to matter, not a measured object.
The Sun is about 109 times wider than Earth, and about 1.3 million Earths would fit inside it by volume. Even so, the Sun is a fairly ordinary star: the red supergiant Betelgeuse is roughly 700 times wider than the Sun.
It is a simplification. A hydrogen atom is about 63,000 times wider than its nucleus, so the nucleus fills only about 4 parts in 10¹⁵ of its volume. The rest is not empty: it is filled by the electron cloud, a probability pattern, and by fields.
A light-year is the distance light travels in one year: about 9.46×10¹⁵ m, or 9.46 trillion km. It measures distance, not time. The nearest star after the Sun, Proxima Centauri, is 4.25 light-years away.
An order of magnitude is a factor of ten. A person (1.7 m) and the Earth (1.3×10⁷ m) differ by almost 7 orders of magnitude, because the Earth is about 7.5 million times bigger. On a logarithmic scale each step of one power of ten is the same distance.
The sizes in this simulation span more than 40 powers of ten. On a straight (linear) scale, everything smaller than the largest object would shrink to an invisible dot. A log scale gives each factor of ten equal space, so atoms, cells, planets and galaxies can all be compared.
Values are rounded and taken from sources such as NASA fact sheets, CODATA, the IAU and published papers; each object lists its source. Many things have no sharp edge (atoms, nebulae, galaxies), so their size depends on how it is defined, and Advanced mode gives the definition and range. The drawings are schematic, but the sizes are to scale.
The 3D views (atom, nuclei, DNA, Earth and Moon, Solar System, Milky Way, cosmic web) are built in code by SciSim. Earth, Moon, galaxy and cosmic-web textures are generated schematic images, not photographs, and are labelled as such in each view. Earth’s coastlines are rasterised from the Natural Earth 1:50m land data (public domain, via the world-atlas package).