Our star maps aren’t like any other star chart
Take a look at the samples, explore and zoom in. The programs to produce celestial charts are not even close to this level of detail. They cannot produce high-quality star chart prints. Also, GreaterSkies Universe posters are beautiful.
All the stars up to magnitude 7 that were visible are plotted, with an approximation of their actual colors and with an area corresponding to their magnitude. This is usually between 7000 and 8000 stars.
Planets, moon and sun (the orange point) are also shown in the sky chart, as well as constellations and star names.
The science behind the celestial chart posters
I wrote the program that computes the positions of stars and planets, and that generates the map, in Common Lisp -a programming language invented back in 1958 and that I rather enjoy using-, and the celestial coordinates come from the HYG database. Over the last years I have worked in optimizing the renderization of the map, striving to make it both accurate and beautiful.
For this is not a normal celestial chart, intended just to show where major stars are located: every tiny dot in your map corresponds to a star that was actually there. The positions are accurate for dates between around 1900 and 2100; we still haven’t implemented the extra computation to produce accurate star charts beyond these dates.