Install astro-tcltk by entering the following commands in the terminal:
sudo apt update sudo apt install astro-tcltk
Description:
Tcl/Tk packages for astronomy
This metapackage will install packages that are useful to develop Tcl/Tk applications for astronomy.
Homepage: http://blends.debian.org/astro/
Version: 1.1ubuntu2
Section: universe/metapackages