Online Tool Store
Star Chart Viewer
Enter a date, time, and approximate latitude to see an illustrative star chart of major constellations likely visible overhead, generated from simplified seasonal visibility rules.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Illustrative only — uses simplified seasonal/hemisphere rules, not real astronomical ephemeris data. For precise positions, use a dedicated planetarium app.
How it works
- Enter a date, time, and approximate latitude for your viewing location.
- The tool derives a season from the date and hemisphere from the latitude sign.
- A small illustrative set of constellations typically prominent in that season/hemisphere combination is drawn on the chart.
FAQ
Is this astronomically accurate?
No — it uses simplified season and hemisphere rules to pick a plausible small set of well-known constellations, not real ephemeris calculations for star positions at your exact time and coordinates. Treat it as illustrative, not a navigation or observation tool.
Why do the visible constellations change with latitude?
Constellations near the celestial poles are only visible from one hemisphere, and the overall night sky flips between the northern and southern hemispheres by season — the tool applies that flip based on the sign of your latitude.
What should I use for real stargazing?
A dedicated planetarium app (which uses your device's GPS, compass, and real astronomical data) will show accurate real-time positions — this tool is meant for quick learning and casual planning, not precise observation.
Illustrative chart vs. a real planetarium app
| Feature | This viewer | Planetarium app |
|---|---|---|
| Instant, no location permission needed | ✓ | ✗ |
| Precise real-time star positions | ✗ | ✓ |
Great for a quick learning overview before a stargazing trip; bring a real planetarium app for pinpointing exact positions outside.