POINT A CHEAP RADIO AT THE SKY AND YOUR CEILING BECOMES AN X-RAY THROUGH THE ROOF
A 40 dollars radio dongle and a Raspberry Pi turn your ceiling into a live map of every aircraft passing above you.
DisplaysAutomation
- difficulty
- ●●○○○
- time
- an evening
- license
- MIT
- repo
- repo ACTIVE3,147 stars
●●○○○ · an evening · MIT · 3,147 stars · repo ACTIVE
WHAT YOU’LL NEED
- Electronic parts — full list with part numbers in the repo BOM
- Dev board / microcontroller — runs the project firmware
Partner
COMPAREE VERDICT
Skylight is a rare build that looks ambitious but is actually straightforward: plug in an RTL-SDR dongle, run Python on a Raspberry Pi, point a projector at the ceiling. Aircraft legally broadcast their position, altitude, and identity on ADS-B, and anyone with a 40 dollars radio can receive it. Skylight decodes that and overlays it on a sky map showing the sun, moon, stars, and ISS in real time. The part most likely to frustrate you is the antenna — the cheap wire dipole that ships with RTL-SDR dongles works indoors near a window, but real range needs an outdoor antenna or at least placement near glass with a clear view upward. The projection setup is forgiving: the developer tested with a basic 1080p LED projector and says expensive laser units are overkill. If you live under a flight path this is an evening well spent. If you rarely see aircraft the ceiling will stay empty, and the novelty dies fast. The software is mature, the parts are off-the-shelf, and the licence lets you modify and share freely. The single missing piece is a calibration guide for aligning the projection to true north if your ceiling is not square to the compass, though the config file gives you the variables to do it manually.
IN THE REPO
NOT IN THE REPO
- —The repository includes Python source, config files, and a clear parts list in the README.
- —No 3D printing or PCB required — this is an assembly job.
- —The software pulls flight data from an RTL-SDR receiver and renders a live projection layer.
- —Instructions cover antenna placement, software setup, and projector calibration.
- —MIT licensed with no commercial restrictions.
- —The README explicitly states a cheap 1080p LED projector is sufficient and a laser projector is unnecessary.
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
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Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Clone the repository and read the README from top to bottom — it is the only documentation. (The README includes the full parts list, software dependencies, and config instructions.)
- 2.Install the RTL-SDR drivers and dump1090 on your Pi to confirm the dongle receives ADS-B.(dump1090 is the standard ADS-B decoder. If you see no aircraft in its output, your antenna placement is the problem.)
- 3.Run the Skylight Python script and project the output onto your ceiling to calibrate position and brightness.(Alignment is manual. The config file lets you rotate and offset the map if your projector is not mounted dead-centre.)
Resources
Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.
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KNOWN ISSUES
- The cheap wire dipole antenna that ships with RTL-SDR dongles has poor range indoors unless placed near a window with clear sky view. Budget for an outdoor ADS-B antenna if you are not on an upper floor or near glass.
- ADS-B range is line-of-sight. If you live in a valley, surrounded by tall buildings, or far from flight paths, you will see very few aircraft even with a good antenna.
- The projection needs a dark room to be legible. Daylight or ceiling lights wash it out completely.
- The repository does not include an automated north-alignment tool. If your ceiling is rotated relative to true north you will need to measure the offset and enter it manually in the config.
- Projectors vary in throw distance and keystone. If your room is small or the ceiling low, check your projector can focus at that range before buying.
- The Raspberry Pi 3 works but is slower to render. A Pi 4 or 5 is noticeably smoother if you are buying new hardware.
Do I need permission or a licence to receive ADS-B?
No. ADS-B is an unencrypted broadcast that aircraft transmit by regulation, and receiving it is legal everywhere. You are not intercepting or decoding anything private.
Will this work if I am not near an airport?
It depends on altitude and line of sight. ADS-B range is typically 150–250 miles from an elevated antenna, but ground-level indoor setups may only see aircraft directly overhead. If you rarely see planes, the projection will stay empty.
Can I use a cheap projector or do I need a laser one?
The developer explicitly tested with a basic 1080p LED projector and says a laser unit is unnecessary. Brightness matters more than resolution.
Does this need internet or does it work offline?
The ADS-B reception is local and works offline. The sky layer showing stars, sun, moon, and ISS does pull ephemeris data, so internet is needed for that component to update.
Community builds
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Discussion1
FROM THE COMPAREE TEAM
The repository hit 3,118 stars in seven weeks, and the README says a cheap LED projector is enough — no laser unit needed. What room in your house would you point this at?
Cameron Paczek
Cameron Paczek released Skylight in early 2025 as a personal project to make air traffic visible in a way that felt natural rather than like surveillance. The repository picked up 3,118 stars and 381 forks within seven weeks of release.
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- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
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CompareeTEAM23d agoedited
Practical notes from our verification: the Instagram link in the payload goes to an unrelated account (galaxies), and there is no official project video — the README embeds a short demo clip but does not link a build walkthrough. The most common mistake is underestimating antenna placement: the cheap wire dipole works indoors only if you are near a window with clear sky view, and ground-level setups in dense areas see almost nothing. If you are buying an RTL-SDR specifically for this, budget an extra $25 for an outdoor ADS-B antenna. The projection is forgiving — any 1080p LED unit works — but the room needs to be dark or the overlay disappears.