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da-luce/astroterm

A terminal star map written in C that renders real-time positions of stars, planets, constellations and the moon as ASCII art.

Open-source alternative to:Stellarium

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What is it?

astroterm is a planetarium that runs inside the terminal. It computes the positions of stars, planets, the moon and constellation figures for a chosen observer location and date, then draws the sky with ASCII or Unicode characters. Users set latitude and longitude directly or pick a city from a bundled list, and can view past, present or future sky states by specifying a UTC datetime.

The tool offers display options such as colored output, an azimuthal grid, constellation stick figures drawn with braille characters, adjustable star brightness thresholds and animation speed. Running it with a high speed multiplier produces a rotating sky effect, which makes it usable as a terminal screensaver.

It is distributed through Arch, Fedora, Homebrew, Nix and Guix packages, as prebuilt binaries for Linux, macOS and Windows, and can be built from source. Star data comes from the Yale Bright Star Catalog and planetary positions from NASA JPL approximations.

Key features

  • 01Renders stars, planets, the moon and constellation figures in the terminal.
  • 02Sets observer location by latitude and longitude or by city name.
  • 03Shows the sky for any UTC date and time, past or future.
  • 04Supports color, Unicode and braille drawing modes.
  • 05Includes an azimuthal grid and adjustable magnitude thresholds.
  • 06Offers shell tab completions for bash.

Use cases

  • Checking what the night sky looked like at a historical event or location.
  • Previewing tonight's constellations and planets from your city without leaving the shell.
  • Running an animated star field as a terminal screensaver.
  • Teaching basic celestial coordinates with a visual, scriptable tool.

Quick start

  1. 1

    Install via Homebrew

    brew install astroterm
  2. 2

    Run the sky map above Singapore with colors and constellations

    astroterm --color --constellations --speed 10000 --fps 64 --city Singapore

Things to know

  • Native packages are listed for Arch, Fedora, Homebrew, Nix and Guix; Windows only gets a prebuilt .exe.

In collections

CLI & terminal tools

Topics

#terminal#astronomy#ascii-art#tui#command-line#star-map#ascii#console#linux#linux-terminal

FAQ

What is astroterm?
A terminal star map written in C that renders real-time positions of stars, planets, constellations and the moon as ASCII art. astroterm is a planetarium that runs inside the terminal. It computes the positions of stars, planets, the moon and constellation figures for a chosen observer location and date, then draws the sky with ASCII or Unicode characters. Users set latitude and longitude directly or pick a city from a bundled list, and can view past, present or future sky states by specifying a UTC datetime.
Is astroterm free to use? What license does it have?
astroterm is open source under the MIT license. Check the license terms before using it in commercial products.
Is astroterm still maintained?
Updated within 6 months. The last commit to astroterm was on Sep 11, 2026.
What can I use astroterm for?
Checking what the night sky looked like at a historical event or location. Previewing tonight's constellations and planets from your city without leaving the shell. Running an animated star field as a terminal screensaver. Teaching basic celestial coordinates with a visual, scriptable tool.
How do I install astroterm?
Install via Homebrew: brew install astroterm Run the sky map above Singapore with colors and constellations: astroterm --color --constellations --speed 10000 --fps 64 --city Singapore
Where can I get astroterm?
The source code and installation instructions are on GitHub: https://github.com/da-luce/astroterm

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