Astroterm: A Planetarium for Your Terminal

Astroterm is a lightweight, open-source planetarium written in C that renders the sky in a terminal using ASCII or Unicode characters. It shows the positions of stars, planets, the Moon, and constellations for a chosen observation time and location, including historical or future skies; without a specified date, it uses the system’s current time. Its purpose is to make an interactive sky map available from the command line, with visuals designed to remain fast and adaptable to different terminals.

Users can set latitude and longitude directly or choose a city, and adjust which stars appear by setting a brightness threshold. Options add constellation stick figures, an azimuthal grid, color, metadata, and braille rendering, as well as control animation speed and frame rate. Examples demonstrate an animated “spinning globe” effect and recreating the sky over Florida on the morning of the Apollo 11 launch. The project offers installation through package managers including Arch, Fedora, Homebrew, Nix, and Guix, alongside prebuilt executables for major platforms and instructions for building from source. Its MIT license and contribution guidance invite users to report bugs and suggest improvements; the documentation also notes practical issues such as configuring a Unicode-capable locale.