How Tell the Sky works

Last updated 7 November 2026

What it is

Tell the Sky is a free app for the web, iPhone, iPad and Android. You write a message on a glowing paper lantern and let it go. It drifts across a live world map on the real wind until it passes over a stranger, who catches it, reads every message on it, adds one of their own and lets it go again. Every lantern leaves a trail of where it has been and who caught it.

A message can be anything: a wish, a story, encouragement, a secret, or something you are letting go of.

How it works

Write. Your first message can be up to 2,000 characters, room for a short story. Each person who catches it adds a line of up to 500.
Launch. From where you are, or from a town or city anywhere in the world. Hold to let it go.
Drift. It rides real wind forecasts across the map. Once it is flying, nobody can steer it, except to raise or lower it into a different wind once a day.
Catch. When a lantern drifts over someone with catching turned on, the sky tells them. They catch it, read the whole chain, add their message and release it again, and their city is stamped on its trail.

The real wind

Lanterns are moved by NOAA’s GFS global weather forecast, the same public data meteorologists use. It is updated every six hours, at several heights in the sky. Nothing about a lantern’s course is made up.

Lanterns fly at jet-stream height, where winds often blow at 80 to 140 mph, so a lantern can cross a continent or an ocean in a few days. Mid-latitude winds blow mostly west to east.
Raise or lower it once a day. There are three heights, from about 28,000 to 40,000 feet, each with its own wind. The sender and everyone who has caught a lantern share one daily change. It picks a different wind, never a destination.
The flame lasts about 14 days, and every catch fills it up again. Over open sea it burns at half the rate, so a lantern has a real chance of making a crossing.
If the flame goes out over the sea, the lantern becomes a message in a bottle and drifts on NOAA’s real ocean-current forecast until it washes up near someone on a coast.
You can watch it at any time on the live map, with its trail and the path the wind is likely to take it.

Three ways to send

Lanterns ride the high winds and can cross oceans and continents.
Blimps have a little motor: pick a destination town and a speed. A tailwind speeds a blimp up and a headwind slows it down. Once it arrives it drifts on with the wind, and anyone who catches it can give it a new destination.
Bottles are thrown into the sea from a coastal town and drift on real ocean currents, much more slowly: they have 90 days at sea.

Is it free?

Yes. Tell the Sky is free on every platform, with no ads, no in-app purchases and no tracking. Nobody can pay to choose who catches a lantern. Anyone can watch the map; to send or catch lanterns you sign in with Google, Apple or an email address. You must be 18 or older.

Your location stays coarse

Tell the Sky never stores or shows anyone’s exact location.

Your account keeps only a coarse area. You pick a town or city from a list, or use your current location, and your phone rounds it to a coarse area before anything is sent.
The map, trails and messages show places at city level. To anyone but the sender, a lantern’s trail starts at the city-sized area around where it was launched, not the spot itself.
A blimp’s destination is a town-sized area, never a point, and it never waits over it, so nobody can aim one at a house.
Who catches a lantern is decided fairly among the people it passes over. Nobody, the sender included, can pick the catcher.
Anyone can watch a lantern fly and see its name, the cities it passes and the names of the people who sent and caught it. Only the people on its chain read its words and see each other’s home towns.

The details are in our Privacy policy.

Common questions

Who can read my message?

Only the people on its chain: you, and each person who catches it. Everyone else can see it fly, but not what it says.

Can I choose who catches it?

No. The wind decides where it goes, and the app takes fair turns among the people it passes over who have catching turned on. The randomness is the point.

How do I catch a lantern?

Turn on Catch lanterns in Settings and set your location. When one drifts over your area the app tells you, and you have a few minutes to catch it. Once you have caught it you have 15 minutes to add your message and let it go. You can catch up to three a day.

How many can I send?

Up to three a day, lanterns, blimps and bottles together, and one of them can be a blimp.

What if nobody catches it?

It keeps drifting until its flame runs out. A quiet sky usually just means nobody is under it yet.

Can I write without my name on it?

Yes. Sign any message as “a stranger” and nobody reading it sees who wrote it. Tell the Sky itself still knows, so reports and blocks keep working.

What if I read something unkind?

A short list of slurs is turned away before it is posted. Report anything else from the ⋯ button beside a message or lantern, where you can also block the person who wrote it. A moderator looks at every report.

Can messages be translated?

Yes. Translate any message into your language with one tap.

How do I delete my account?

From Settings, at any time. What is deleted and what stays is on the Support page.

Get the app

Tell the Sky is on iPhone, iPad and Android, and on the web at tellthesky.com.

Apple and the Apple logo are trademarks of Apple Inc., registered in the U.S. and other countries. App Store is a service mark of Apple Inc. Google Play and the Google Play logo are trademarks of Google LLC.

Questions go to [email protected]. Help with the app is on our Support page, the rules are in our Terms of Use, and our standards against child abuse are on the Child safety page.