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Another interesting thing is we get a massive surge in neutrinos when a Supernova happens. They are uncharged leptons so they are really hard to detect (smaller than an electron but no charge so they hardly ever react with anything making them really hard to detect you basically need a huge number of relativly high energy ones passing through the earth and then you get a chance one will set off a detector). Because there is so much we don't know about them any chance to detect a whole bunch is useful plus because of their low mass and origins (in the supernova) we know a lot (the type of reactions that caused them) and we know where they came from the supernova, and then we can do stuff like compare the how long they take to arrive compared to the light from the supernova (for a long time people were not really sure if neutrinos had mass or not, some that were detected during a previous super nova where slightly slowing than light in line with what relativity would predect (they only came in a few seconds behind the light which means they were going really really fast). So it gives us insight into an interesting particle (which is important to astronomy because it is one of the canidates for contributing to dark matter) and certain aspects of nuclear physics, relativity, ect.


Also some supernovas (type Ia) happen almost exactly the same way every time. Thus they have the same luminosity when they occur and are thus used as one of the methods of determining the distance of really distant galaxies.(basically they look at changes in luminosity of the galaxy, and if they can tell it is a type Ia supernova they can determine the distance of the galaxy based off the absolute luminosity of the supernova)

info on supernovas
http://en.wikipedia.org/wiki/Type_I_supernova
(no I don't always just go to wikipedia, but is just normally the best and most clear option, especially if you don't want to get to technical)

Well the data gathered from that supernova (both neutrinos, and visible light) were used for the calculatin of the mass of a neutrino (before this it was a basially open question rather neutrinos actually had mass). So providing proof that neutrinos had mass told us a lot about particle physics.