Shadows is a software package for the calculation and drawing of sundials and astrolabes, available as a freeware in its base level.
It has been developed by François Blateyron, software developer and amateur astronomer, who made it available on Internet since 1997 and continues to improve it.[1] It is used worldwide by thousands of sundial enthusiasts.[2] It is compatible with Windows 11/10, 8.x and 7. Shadows is available in three levels: Shadows is a freeware; Since version 3.0, it also supports the creation of astrolabes.
The Shadows software is developed for the Windows operating system. It is simple to use but does not aim to be universal. It
draws the sundial on screen and prints it to various scales to act as a template during fabrication. The sundials show solar time and can include longitude correction and equation of time. It also can draw ancient or unequal hours such as Italian and Babylonian and even draw azimuth and altitude curves. It has an animation feature so the shadow of the style can be simulated on the screen. The results can be copied as an image or a vector graphics (metafile or DXF) for use in CAD programs or machine tools.
In 2005, the French astronomical society, Société Astronomique de France (SAF) awarded Shadows with the Julien Saget prize for the Shadows software.[3]. In 2023, the North American Sundial Society (NASS) awarded Shadows with the Sayer Dialing Prize. [4].
The astrolabes are interactive and can be manipulated on screen by rotating the Rete and the Alidade using the mouse.
Several curves and graphs are available: equation of time, solar graph with horizon mask, duration of the day, direction rose.
It is translated in 18 languages (French, English, German, Spanish, Italian, Portuguese...)