diy:

The Cyanometer Is a 225-Year-Old Tool for Measuring the Blueness of the Sky
This simple device was invented in 1789 by Swiss physicist Horace-Bénédict de Saussure and German naturalist Alexander von Humboldt who used the circular array of 53 shaded sections in experiments above the skies over Geneva, Chamonix and Mont Blanc. The Cyanometer helped lead to a successful conclusion that the blueness of the sky is a measure of transparency caused by the amount of water vapor in the atmosphere. You can learn more at the Royal Society of Chemistry. 
Source: thisiscolossal
ifuckingloveminerals:

Gilmarite
El Guanaco Mine, Guanaco (Huanaco), Santa Catalina, Antofagasta Province, Antofagasta Region, Chile
astronomicalwonders:

The Sun and Moon
During the Annular eclipse, around 200 people came to the observatory in Placerville California for viewing.  After the main crowd had thinned, some astronomers did have an opportunity to put a camera into the telescope and gather a bit of imaging data.  This is one of the images taken around 7:07 PDT on May 20th 2012.  It was well after the maximum of the eclipse (the viewing lines were very long at the max and the views were very nice). 
Credit: starshadows.com/smoot
thecraziethewizard:

Jeremiah Probodanu