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gunerguner/AdAstra

An offline-capable interactive web app that reconstructs the local night sky in the browser for any place and time.

Open-source alternative to:Stellarium

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Last commit
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What is it?

Ad Astra is a browser-based sky simulator. You pick an observing site, either from a list of preset cities or by entering latitude and longitude, and a moment in time. The app then draws the local sky: bright stars, constellation lines, the Sun, the Moon, and the planets from Mercury to Neptune, updated as Earth's rotation and orbit change.

The view can be dragged and zoomed, and jumped to the cardinal directions or the zenith. A timeline lets you play, pause, or scrub through about eight hours, and step forward or back by hours, days, years, decades, or centuries. Layers such as the Milky Way, ecliptic, celestial equator, and coordinate grids can be toggled, and sky color changes through daylight, twilight, and night. The production build includes a Service Worker, so it can open offline after the first load.

The project is a popular-science simulation meant for learning constellations and the day-night cycle, not for professional observing or navigation. It is a static frontend with no runtime backend, built on React, TypeScript, Three.js with WebGL2, and Astronomy Engine running in a Web Worker.

Key features

  • 01Shows bright stars, constellation lines, the Sun, Moon, and planets for a chosen location and time.
  • 02Supports city presets or manual latitude and longitude input.
  • 03Timeline playback ranges from real time to 100 years per second.
  • 04Layers such as the Milky Way, ecliptic, and coordinate grids can be toggled.
  • 05Sky color and star visibility follow the Sun's altitude through twilight stages.
  • 06Works offline after the first load via a Service Worker.

Use cases

  • Learning to recognize constellations and their seasonal positions.
  • Understanding how the sky changes through the day, night, and twilight.
  • Exploring what the sky looked like at a given place and date.
  • Showing a classroom or outreach audience how Earth's rotation and orbit affect what we see.

Quick start

  1. 1

    Clone the repository

    git clone https://github.com/gunerguner/AdAstra.git
  2. 2

    Enter the project folder

    cd AdAstra
  3. 3

    Install dependencies

    pnpm install --frozen-lockfile
  4. 4

    Start the development server and open the local URL

    pnpm dev

Things to know

  • The app is a popular-science simulation and is not suitable for professional observing, navigation, or research.
  • Requires Node.js 20.19+ or 22.12+, pnpm 10, and a browser with WebGL2.
  • The metadata shows no license, so reuse terms are unclear despite the README's MIT statement.

Topics

#astronomy#webgl#threejs#react#typescript#pwa#simulation#education

FAQ

What is AdAstra?
An offline-capable interactive web app that reconstructs the local night sky in the browser for any place and time. Ad Astra is a browser-based sky simulator. You pick an observing site, either from a list of preset cities or by entering latitude and longitude, and a moment in time. The app then draws the local sky: bright stars, constellation lines, the Sun, the Moon, and the planets from Mercury to Neptune, updated as Earth's rotation and orbit change.
Is AdAstra free to use? What license does it have?
AdAstra has no declared license. Its code is public, but without a license you have no explicit permission to reuse it; ask the author before relying on it.
Is AdAstra still maintained?
Actively maintained. The last commit to AdAstra was on Oct 13, 2026.
What can I use AdAstra for?
Learning to recognize constellations and their seasonal positions. Understanding how the sky changes through the day, night, and twilight. Exploring what the sky looked like at a given place and date. Showing a classroom or outreach audience how Earth's rotation and orbit affect what we see.
How do I install AdAstra?
Clone the repository: git clone https://github.com/gunerguner/AdAstra.git Enter the project folder: cd AdAstra Install dependencies: pnpm install --frozen-lockfile Start the development server and open the local URL: pnpm dev
Where can I get AdAstra?
The source code and installation instructions are on GitHub: https://github.com/gunerguner/AdAstra

Summary generated by AI from the project's README. GitHub stats refresh daily.

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