The method
How accurate are
star maps?
A good star map isn't decorative art — it's a precise astronomical calculation. Ours place 4,995 real stars, all 88 constellations, the Sun, the planets and the Moon in its true phase at the exact positions they held over your moment. And you can verify any map yourself.
The data behind every map
We don't place stars by hand or by feel. Two professional datasets — the same ones researchers use — do the work, computed with the open Skyfield library.
DE440
NASA JPL ephemeris — Sun, Moon & planets
Hipparcos
ESA star catalogue — 4,995 real stars
88
Constellations, at true positions
Skyfield
Open, peer-reviewed astronomy
How the sky is computed
You give three things — a date, a time and a place. From those we work out how the Earth was oriented at that instant, then project every celestial body onto the sky exactly as it appeared from your spot.
Your moment
Date · time · place
The calculation
DE440 + Hipparcos, via Skyfield
Your poster
The real sky, print-ready
You choose one of two true views — Your Sky (the dome directly overhead) or All Stars (the full celestial sphere) — and the Moon is drawn in its real phase for that night.
Why most “star maps” aren't
Many personalised “star maps” sold online are decorative: stars scattered for visual balance, not placed at their true coordinates, with the date reduced to a caption. That can look pretty — but it isn't a record of anything. Ours is built the other way round: the real sky first, then made beautiful.
Questions about accuracy
Are star maps scientifically accurate?
A well-made one is. The position of every star, planet, the Sun and the Moon over a given place at a given moment is a solved problem in astronomy — it can be computed to high precision. Our maps do exactly that, so they are an accurate record of the real sky, not a decorative arrangement of dots. Many products sold as 'star maps' simply scatter stars for looks; ours are a genuine calculation.
What data are Under These Stars maps based on?
Two professional datasets. Planet, Sun and Moon positions come from NASA JPL's DE440 planetary ephemeris — the same high-precision model used in spacecraft navigation and research. Star positions come from the Hipparcos catalogue, giving 4,995 real, naked-eye-visible stars across all 88 constellations. The astronomy is computed with Skyfield, an open, peer-reviewed library.
Can I check that my star map is correct?
Yes, and we encourage it. Open free planetarium software such as Stellarium, set the same date, time and location you used, and compare. The constellations, the bright stars, the Moon's phase and the planets' positions will line up with your poster. That is the whole point — it's verifiable, because it's real.
Why does the same date look different from a friend's map?
Because the sky depends on where you are and the exact time, not just the date. The Earth's rotation and your location on it change which stars are overhead and where the horizon cuts the sky. So the same evening in Mumbai and in Delhi produces slightly different maps — which is exactly why yours is personal to your moment.
Is the Moon drawn in its real phase?
Yes. The Moon is rendered in the exact phase it held on your date — the same crescent, half or full moon that was actually in the sky that night — computed from the same ephemeris, not a generic symbol.
Real data. Real sky. Really yours.
Give someone the exact sky from the night that mattered — computed, accurate, and beautiful.
Create your star map →Starting at ₹99 · PNG + PDF · Print-ready · Or see what a star map is