Seen from inside the 780 ft. linear optical tunnel of Kitt Peak National Observatory's McMath-Pierce Solar Telescope, sunlight is reflected from the three mirror heliostat, through a series of mirrors in the tunnel to the observation room where is it analyzed with spectrographs. McMath-Pierce Solar Telescope, built in 1962, west of Tucson, AZ., is the largest solar telescope in the world. Photo taken Wednesday, October 23, 2013.

Ron Medvescek / Arizona Daily Star