WA also puts the mass-energy of two solar masses at 3.574 x 10^47 J. So the initial calculation seems about right. My very-amateur-physicist guess is that the d

WA also puts the mass-energy of two solar masses at 3.574 x 10^47 J. So the initial calculation seems about right. My very-amateur-physicist guess is that the difference is because a supernova only converts a small fraction of the star's mass into energy - the remaining mass is thrown outwards to form planets and such. [1] - http://www.wolframalpha.com/input/?i=mass-energy+of+two+solar+masses http://www.wolframalpha.com/input/?i=mass-energy+of+two+sola...