Sunstar

Visitors to Pasadena and the Northeastern portion of the Los Angeles basin might occasionally catch a glimpse of the elusive Sunstar, an art exhibit perched high atop Mt. Wilson.  A collaboration between artist Liliane Lijn and astrophysicist John Vallerga, the Sunstar is an array of precisely aimed prisms that reflect a spectrum 250 yards long to specific locations.  Observers will see a bright point of a single color that depends on their location within that spectrum.

Outside of that target area, the Sunstar is not visible.  The observatory periodically moves the Sunstar to target different areas, so catching a glimpse is a matter of being lucky to be at the right place at the right time. 

http://www.lilianelijn.com/portfolio-item/sunstar-2018/