Light from the stellar explosion that created this energized cosmic cloud was first seen on planet Earth in October 1604, a mere 400 years ago. The supernova produced a bright new star in early 17th century skies within the constellation Ophiuchus. It was studied by astronomer Johannes Kepler and his contemporaries. Recent data has shown relative elemental abundances typical of a Type Ia supernova, and further indicated that the progenitor was a white dwarf star that exploded when it accreted too much material from a companion. The explosions discussed in the publication would produce a remnant that looks like Kepler but with the presence of an oxygen-neon-iron white dwarf at the center.