Cosmic Address

You are here — Northern Hemisphere, the Prime Meridian
  1. Earth6,371 km

    The third rocky planet from the Sun — the only known place in the universe that builds telescopes to find out where it is.

    Source: IUGG 1980 (mean radius)

  2. Solar System123 AU

    One yellow dwarf star and everything gravitationally bound to it. The Voyager 1 probe crossed the heliopause in 2012 and is still moving outward.

    Source: Voyager 1 heliopause crossing, 2012

  3. Milky Way Galaxy100,000 light-years

    A barred spiral galaxy of 100–400 billion stars. The Sun sits in the Orion Arm, about a third of the way out from the galactic centre.

    Source: Sloan Digital Sky Survey

  4. Local Group10,000,000 light-years

    A small cluster of ~80 galaxies, gravitationally bound. Andromeda is its largest member and is heading toward us — collision in ~4.5 billion years.

    Source: NASA Extragalactic Database

  5. Virgo Supercluster110,000,000 light-years

    A web of ~100 galaxy groups including the Local Group. Now understood to be a lobe of the larger Laniakea structure.

    Source: Tully 1982

  6. Laniakea Supercluster520,000,000 light-years

    Hawaiian for 'immeasurable heaven.' A galaxy supercluster of ~100,000 galaxies — mapped in 2014 by tracking which way each galaxy is being pulled.

    Source: Tully et al. 2014

  7. Observable Universe93,000,000,000 light-years

    Every direction we can possibly see from Earth, bounded by the distance light has had time to travel since the Big Bang. The unobservable part is presumed much larger.

    Source: Planck mission, 2018

In the 1970s Carl Sagan and the team behind the Voyager probes wrote out humanity's address on the side of a gold record we then flung past Pluto: Earth, Sol, Orion Arm, Milky Way, Local Group, on outward. This is that same address, generated for you. Type your latitude and longitude. The tool prints seven rungs of where-you-are, starting with the rock under your feet (6,371 km across) and ending with everything light has had time to reach since the Big Bang (about 93 billion light-years across). The numbers are real, sourced from the IAU, NASA, and the Planck mission — and your data goes nowhere. The calculation is seven lookups in a constants table.

Built by Bob Article by Lace QA by Ben Shipped

How to use

  1. 1

    Type your latitude (-90 to 90) and longitude (-180 to 180). If you don't know them off-hand, click 'Use my location' — the browser asks first, and the coordinates round to four decimals before they touch any code.

  2. 2

    Read the green hemisphere banner at the top. That's the only piece of your address that genuinely varies — every Earth observer shares the next six rungs.

  3. 3

    Scan down the seven nested cards. Each one carries the level's name, a one-sentence factual description, its characteristic size (locale-formatted with commas), and the authoritative source for the number.

  4. 4

    Click 'Copy address' to drop a shareable version on the clipboard. The format is plain text — useful for an email signature, a social bio, or a postcard back home.

Frequently asked questions

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What the Cosmic Address generator produces

The Cosmic Address generator turns a latitude and longitude into a nested “you are here” address for the universe. Type coordinates, or let the browser fill them in with your permission, and the tool prints the rungs from Earth outward: Solar System, Milky Way, Local Group, Virgo Supercluster, Laniakea, and the observable universe. It is part astronomy lesson, part postcard, part tiny existential mirror. Not bad for two numbers.

51.4779, 0 becomes Northern Hemisphere, the Prime Meridian. -33.8688, 151.2093 becomes Southern Hemisphere, Eastern Hemisphere. The cosmic rungs stay the same, because every human shares the same larger address.

The output is structured and cited. Each rung includes a name, a short description, a size, a unit, and a source. Earth uses the IUGG mean radius. The Solar System uses the Voyager 1 heliopause crossing. Laniakea comes from Tully and colleagues’ 2014 mapping of galaxy flows. The observable universe uses Planck 2018 cosmological parameters. The tool does not ask for an account, and your coordinates are not sent to a server.

Why use a cosmic address generator instead of asking Big Software

You can ask ChatGPT, Microsoft Copilot, or a search engine for your cosmic address. You might get a fine answer. You might also get a confident soup of astronomy terms with a number rounded from nowhere. Big Software is very good at turning one clear question into a chat, a sidebar, an account prompt, a history log, and three buttons you did not ask for.

This is the opposite. The Cosmic Address generator does one job. It takes two coordinates, checks the hemisphere, and prints the same seven astronomy rungs every Earth observer belongs to. No chatbot performance. No prompt engineering. No “try the app” detour. It is the full tool.

Google Earth lets you zoom from your street to the planet. Wikipedia can explain the Local Group. NASA has the source material. Those are useful. They are also separate stops. This tool stitches the address together in one readable stack, with the source beside each number, so a student, a teacher, a parent, or a bored person at 1:17 a.m. can see the whole thing at once.

The point is not that the universe changes when you type your coordinates. It does not. The point is that the first line changes enough to make the address yours. Your hemisphere is the return label. The rest is the shared postal route for everyone on Earth.

How the Cosmic Address generator works

The tool is built around a constants table, not a live astronomy API. That matters. Most of the address is made from stable reference facts: Earth’s mean radius is 6,371 km, the Solar System heliopause is about 123 AU out, the Milky Way is roughly 100,000 light-years across, and the observable universe is about 93 billion light-years across. Those figures do not need a network call every time someone opens the page.

The only calculation that depends on your input is the hemisphere label. Latitude above 0 is northern. Latitude below 0 is southern. Latitude 0 is the Equator. Longitude above 0 is eastern. Longitude below 0 is western. Longitude 0 is the Prime Meridian. The tool accepts latitude from -90 to 90 and longitude from -180 to 180. Anything outside that range is not a real Earth coordinate, so the tool rejects it instead of trying to be clever.

Here is the worked example from the default input. The Royal Observatory in Greenwich is at 51.4779 latitude and 0 longitude. The latitude is positive, so the label starts with Northern Hemisphere. The longitude is exactly zero, so the tool uses the special label the Prime Meridian. The first line reads: You are here — Northern Hemisphere, the Prime Meridian. Then the seven rungs print underneath, with Earth first and the observable universe last.

Customizing the output

The Cosmic Address generator keeps the controls short because the universe is already doing enough. You can type coordinates manually, use your current location, or copy the finished address. The copied version is plain text, which makes it easy to paste into a classroom slide, social bio, notebook, email signature, or message to a friend who enjoys being lightly humbled by cosmology.

ControlAccepted valueWhat it changes
Latitude-90 to 90Sets northern, southern, or Equator label
Longitude-180 to 180Sets eastern, western, or Prime Meridian label
Use my locationBrowser permissionFills latitude and longitude, rounded to 4 decimals
Copy addressOne clickCopies the plain-text cosmic address

If you do not know your coordinates, use the location button. Your browser will ask first. If you would rather not share location with the page, type a city coordinate instead. For example, Tokyo is about 35.6762, 139.6503, which gives Northern Hemisphere, Eastern Hemisphere. Buenos Aires is about -34.6037, -58.3816, which gives Southern Hemisphere, Western Hemisphere.

The generated address is not meant to identify your house. It rounds location when using browser geolocation, and the larger rungs are shared by everyone here. It is a cosmic address, not a delivery instruction. Please do not ask the Local Group to sign for a package.

Best practices and caveats

Use this tool for learning, teaching, writing, and perspective. It is great for a classroom opener: ask students to write their street address, then compare it with their cosmic address. It also works well in astronomy clubs, science-fair boards, social bios, and family conversations where someone asks, “Wait, what is Laniakea?”

Do not treat the rungs as a legal or navigational address. A spacecraft cannot fly home from “Laniakea Supercluster” the way a taxi can drive to a street. The address is a nested description of where Earth sits in larger structures. The Voyager golden record used pulsars as a more literal map. This tool gives the human-readable version.

The 93-billion-light-year observable universe number surprises people. The universe is about 13.8 billion years old, but space has expanded while light traveled. The farthest visible matter is now much farther away than 13.8 billion light-years. Cosmology enjoys making normal rulers feel silly.

Some numbers in astronomy shift as measurements improve. The big labels should stay stable for a long time: Earth, Solar System, Milky Way, Local Group, Virgo Supercluster, Laniakea, observable universe. The measured sizes can move at the edges. That is why the tool shows citations. If the reference number changes, you can see what was used.

If you want more personal scale tools, pair this with Age on Other Planets to see your age in Martian or Jovian years, Weight on Other Planets to feel gravity change under your feet, and Heartbeats Since Birth to count a more local kind of cosmic clock.

Related generators and space tools

The Cosmic Address generator sits in the fun end of the science drawer: real numbers, playful framing, no spreadsheet required. For astronomy-adjacent curiosity, try the Moon Phase Calculator to find the lunar phase for any date, or the Sunrise/Sunset Calculator for daylight times by location. If you want the personal-time version of cosmic scale, Life in Weeks turns a lifetime into a grid. It is quieter than a supercluster, but it lands harder.

Microapp’s catalog is built for these small exact moments. Open the tool, get the answer, leave with the answer. Big Software wants to keep you in the building. We are happy if you get what you came for and go outside to look at the sky.

Frequently asked questions

Is my latitude and longitude sent anywhere?

No. The calculation runs in your browser. If you click “Use my location,” your browser asks permission first, then gives the page coordinates. The tool rounds them to four decimals and uses them to label your hemisphere. There is no server-side coordinate lookup behind the article’s examples.

Why is the address mostly the same for everyone?

Because every person on Earth shares the same larger cosmic home. Someone in London and someone in Sydney have different hemisphere labels, but both are on Earth, inside the Solar System, inside the Milky Way, inside the Local Group, inside Laniakea, inside the observable universe.

What is Laniakea?

Laniakea is the galaxy supercluster that contains the Milky Way and about 100,000 other galaxies. Astronomers defined it in 2014 by mapping galaxy velocity flows — basically, which way galaxies are being pulled. The name comes from Hawaiian and means “immeasurable heaven.” Good name. No notes.

Why does the tool include both Virgo Supercluster and Laniakea?

Before Laniakea was mapped, our region was commonly described as part of the Virgo Supercluster. The newer model treats Virgo as a lobe or sub-structure within the larger Laniakea Supercluster. Including both shows the older local layer and the newer larger layer.

Why is the observable universe 93 billion light-years wide?

Light has traveled for about 13.8 billion years, but space expanded while that light was moving. The matter that emitted the oldest light we can see is now about 46 billion light-years away in every direction. Double that radius and you get about 93 billion light-years.

Can I use this for a school project?

Yes. The address rungs include source labels, and the numbers come from standard astronomy references such as the IAU, NASA data, Tully’s supercluster work, and Planck 2018. Still cite the original astronomy source if your teacher asks for formal references.

Is this the same as the Voyager golden record map?

It is inspired by the same idea, but it is not the same map. The Voyager record used pulsars as beacons to point back to Earth. The Cosmic Address generator gives a readable nested address instead: where you are, zooming outward until language runs out of room.