August 13, 2009
Cracked by: duriel , Rohan , udupendra , shrik , Dibyo , Debasish , dheeraj , Rogi , AmK , Logik , Raghuvansh , varuns88.
1. Pierre Janssen
2. The clear yellow line is at 587.49nm in the spectrum
3. Guntur :p
Janssen noticed this wavelength while watching a total solar ecipse in Guntur, which led him to discover Helium.