Star Map Generator
Recreate the exact night sky above any place, date and moment — a personal poster of the stars, generated in your browser. Free, high-resolution, no sign-up.
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Live preview — click to zoom · downloads render at 2000 × 2480 px (300 DPI, A3-ready) · no watermark
How this star map generator works
Pick a place, a date and a moment. The generator converts your local time to universal time, computes the sidereal time for your longitude, and rotates the Yale Bright Star Catalog — more than 5,000 stars down to magnitude 6.5, the naked-eye limit — into the exact positions they occupied above your chosen spot. Every dot on your poster is a real star at its real position, not a random scatter.
The chart is centred on the zenith (the point directly overhead), with the horizon as the outer ring. East appears on the left, the same orientation used on planispheres and professional sky charts, so you can hold the poster overhead and match it to the real sky.
Extras are computed with standard low-precision planetary theory: the positions of the Moon, Mercury, Venus, Mars, Jupiter and Saturn for that moment, plus a Milky Way band drawn from its real astronomical outline.
What people use star maps for
- Anniversaries & first meetings — “the night we met”, framed.
- Weddings — the sky above the venue at the vows.
- Births — the sky on the day a child arrived.
- Remembering someone — a meaningful night, kept.
- Stargazing & astronomy homework — a printable chart for a real observing night.
Everything is computed and drawn in your browser. No account, no watermark, and the high-resolution download is free.
Frequently asked questions
Is the star map accurate?
Yes. Star positions come from the Yale Bright Star Catalog (epoch J2000) and are rotated using standard sidereal-time formulas — the same approach used by planetarium software. Planetary positions use Paul Schlyter’s low-precision method, accurate to a couple of arcminutes, which is far below the resolution of a poster.
Why is east on the left?
The chart shows the sky dome as you see it when looking up. If you lie on your back with your head pointing north, east is on your left. This matches every planisphere and sky atlas — flip it horizontally and it would show the sky as seen from outside the sphere, which nobody can see.
What time should I pick?
The moment that matters to you. If you only know the date, 21:00 or 22:00 local time is a good default — the sky is dark and the star field differs noticeably from midnight, so the poster still looks specific to that evening.
Can I use a date in the past or future?
Any date from 1900 to 2100 works. Star positions change extremely slowly (proper motion shifts bright stars by arcminutes per century), so a 1960s sky is rendered faithfully. Planet positions are accurate across this whole window.
How do I print it at poster size?
Download the PNG (2000 × 2480 px) — that is enough for a crisp A3/12×18 in print. For larger formats or professional printing, download the SVG, which scales to any size without pixelation.
Does anything get uploaded?
No. The star catalog downloads to your browser once and all maths and drawing happen locally. Share links only encode your inputs in the URL.