A planetary scanner (also called an orbital scanner) is a type of image scanner for making scans of rare books and other easily damaged documents. In essence, such a scanner is a mounted camera taking photos of a well-lit environment. Originally, such scanners were expensive and could only be found in archives and museums, but with the availability of cheap, high-resolution digital cameras, DIY planetary scanners have become affordable, and for instance are being used by volunteer scan providers for Project Gutenberg.