Where Does Our Data Come From?

1. Data Source: HYG Catalog

Our star data comes from the HYG catalog — a real star catalog merging Hipparcos, Gliese and the Yale Bright Star Catalog, with J2000 coordinates, magnitudes, distances and spectral types for about 120,000 stars. We include 107,838 of them across all 88 constellations, every one traceable to source data.

• Position: Right Ascension (RA) & Declination (Dec), J2000 epoch
• Distance: light-years derived from parallax measurements
• Brightness: G-band magnitude

Data version: HYG Database v4.1 (epoch J2000.0)

2. How Are Sky Positions Computed?

The sky you see is not a static image. We compute it in real time with the open-source astronomy-engine:

• Earth rotation, observer timezone, latitude & longitude
• Observation date and time
• Precession and nutation corrections
• Real-time positions of the Sun, Moon and planets
• Azimuth and altitude of every star

3. 3D Rendering Method

The 3D sky places stars directly from catalog RA/Dec and distance, projected into three-dimensional space outside the solar system, preserving relative near/far distances; star brightness maps to real magnitude.

4. Honest Limitations

• The catalog is a DR3 snapshot; a few distances/magnitudes come from public reprocessed data and may differ slightly from the latest release
• A screen cannot fully reproduce the naked-eye sky — displays only approximate star brightness and color
• Some constellation lines are illustrative; no such lines exist in the real sky
• No live telescope imagery is used; every position is computed mathematically