Start with a patternOrion, the Plough and Cassiopeia are free for everyone.
A practical constellation trainer
Your sky is the lesson.
Learn the patterns that stand out where you are, practise until they feel familiar, then take that confidence outside.
Android · Free to install
A simple way in
From a pattern to your own sky.
Start with one recognisable shape. Learn it, practise it without the guides, then use it as a familiar place to begin looking up.
Recognition is the rewardBuild the habit of finding a figure yourself.
Carry it outsideUse a predicted guide for your time, place and phone direction.
Inside the app
More than a star chart.
A route from a familiar shape to the wider sky around it.
Explore the AtlasAll 88 constellations, with paintings for the playable figures.
Look closerOpen a star to explore its colour, distance, scale and story.
Know what is worth looking forTonight highlights a good place to begin in the sky above you.
Good to know
Questions, answered.
What can I learn?
Bortle Bounded has 40 playable constellation lessons and an Atlas covering all 88 IAU constellations.
Is it a camera star-recognition app?
No. Sky Lens gives you a predicted guide based on your time and place and, in Compass and Live, the way your phone points. It does not identify stars from camera images.
What does it cost?
The app is free to install. Orion, the Plough and Cassiopeia are free; in the UK, one £3.99 Google Play unlock opens the remaining lessons. There are no ads or subscription.
Is it available on iPhone?
Not at launch. Bortle Bounded is for Android on Google Play.
A closer look
See the learning flow in motion.
A short introduction to the app without leaving this page.
Keep looking up
A little help between clear nights.
Practical starting points, a plain guide to light pollution, and sourced stories from the wider sky.
Free constellation guides
Start with Orion, the Plough or Cassiopeia: three bright patterns that give a beginner somewhere solid to begin.
Sky Notes
Short, sourced stories that connect an interesting idea in astronomy to the sky above you.
Understand the Bortle scale
Light pollution changes the detail you see, but it does not stop the sky being worth learning.
What to look for
Choose one bright seasonal pattern, learn how its stars relate, and return to it on the next clear night.
Now on Google Play.
Free to install on Android. Begin with Orion, the Plough and Cassiopeia, then unlock the other lessons when you’re ready.