Sources & credits

Astronomical calculations

Astronomy Engine 2.1.19 by Don Cross, MIT licence. Solar-system coordinates, lunar phases, twilight and seasons are computed, not live telemetry. Terrain, atmospheric variability and telescope alignment are not modeled.

Star catalog

HYG v4.1 by David Nash, based on Hipparcos, Yale Bright Star and Gliese catalogs. The adapted catalog contains stars with V magnitude ≤ 5.5. Field names and selection were changed; no source coordinate edits. Epoch and equinox J2000.0. The chart propagates catalog Cartesian velocity and applies precession/nutation.

The adapted data is shared under CC BY-SA 4.0: download the data and licence. This data licence is separate from the application code.

Images

• Saturn: NASA/JPL-Caltech/Space Science Institute, Cassini “A Farewell to Saturn.”
• Cosmic Cliffs: NASA, ESA, CSA, STScI.
• Pillars of Creation: NASA, ESA, CSA, STScI; processing by Joseph DePasquale, Anton Koekemoer and Alyssa Pagan (STScI).

Image source URLs and credits. NASA logos are not used and no endorsement is implied.

External data

NASA APOD uses the documented WordPress APOD Basic API introduced in September 2026. News headlines come from NASA RSS and link to the publisher. APOD copyright varies; consult each entry before reuse. Weather comes from Open-Meteo under CC BY 4.0, when enabled for permitted noncommercial use or with a commercial key.

Learning

Lessons are original educational explanations with source links, including NASA Science and OpenStax Astronomy 2e. Scientific translations have not been reviewed; the complete content is currently English.