- The main objective of the freestarcharts website is to provide quality star charts for use by amateur astronomers under a “Creative Commons License”. What that means is you are basically free to download, use and/or distribute this work for non-commercial purposes with appropriate attribution. A simple credit of “www.freestarcharts.com” is all that’s required as attribution. You can also create and distribute derived works if they follow the same license. https://freestarcharts.com/contact
- The author distributes the charts in PDF format, and I converted to SVG for use on this site. I recommend downloading the original PDF for printing.
- Silicon dioxide (Wikipedia)
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO2, commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant families of materials, existing as a compound of several minerals and as a synthetic product. Examples include fused quartz, fumed silica, opal, and aerogels. It is used in structural materials, microelectronics, and as components in the food and pharmaceutical industries. All forms are white or colorless, although impure samples can be colored.
