Massive collapsing stars radiate most of their binding energy (about 10^53 ergs) in the form of neutrinos. The rate of such collapses in our galaxy is expected to be greater, perhaps by a large factor, than the supernova rate. John Bahcall estimates a rate of about one collapse every 11 years in our galaxy. Stellar collapses might not exhibit the conspicuous optical show of full-blown supernovas but can still be potent emitters of neutrinos. According to Juan Collar, recently of the University of South Carolina but now with the University of Paris, stellar-collapse neutrinos may have played a role in...