A planisphere is a star chart analog computing instrument in the form of two adjustable disks that rotate on a common pivot. It can be adjusted to display the visible stars for any time and date. It is an instrument to assist in learning how to recognize stars and constellations.
The main disadvantage of this tool is a dependence on the latitude. If it is designed for the particular one, it works properly only in the small range of latitudes around. The planisphere can be bought at most bookstores, but very often just for the local latitude. If you are from north or central Europe and plan to spend holidays in southern Europe, this one cannot be simply used there.
The basic idea was to create a handy utility allowing you to set the desired latitude, display the appropriate sky area on your monitor, and, of course, print it out.
The web application mimics the original planisphere instrument in the form of two adjustable disks that rotate on a common pivot. It can be adjusted to display the visible stars for any time and date.
You turn a wheel to put your time next to your date, and instantly, there's a map of the stars that are above your horizon for that moment. When daylight saving time is in effect, use the minor hour scale. Actually, that hours scale represents local solar time, which slightly differs from standard time.
Settings for December, 15 at 20:00
This tool would have never been spread so widely without translations into various languages.
Despite a good SVG support in major browsers there are still several issues in every particular browser.
The original desktop application has been replaced with a web one and the former is not available any more. This fact sometimes makes those users with the limited internet connection sad. Without an internet access the current web application seems to be useless. But it isn't!
All the texts you can see in the application can be translated online via Transifex web application. You just need to sign up to this service, visit the Planisphere project and ask for creating a new localization group for your language (or join any current one).
Themes are SVG templates that contain unique identifiers which are replaced with the generated content during the processing. All styling is driven by CSS styles.
All the current theming stuff can be analyzed directly in the GitHub repository.
A new design requires a new set of SVG templates. A new color scheme requires just a new CSS file. The latter option is hence lot of easier for any customizations.
For the new design one SVG template per one final page is required. While a single SVG template is sufficient for the screen mode, for printing there are used either two or four separate SVG files according to the selected latitude. The logic inside is rather advanced. But feel free to contact me if you are interested in creating a new one.