'George Hale’s spectroheliograph made it possible to photograph this using one w.l. of light'
the sun
1891: George Hale’s spectroheliograph made it possible to photograph this using one w.l. of light
George Hale’s spectroheliograph made it possible to photograph this using one w.l. of light
George Hale’s spectroheliograph made it possible to photograph this using one w.l. of light
1891
the sun
1891