31. Isotope studies indicate a nearby supernova explosion added fresh material to what became the Solar System. 32. They were also able, on 23 February 1987, to detect neutrinos from a distant supernova explosion . 33. The rate of supernova explosion is not great enough to explain the 100 million year extinctions, 34. In both the primary and secondary star, their cores will eventually collapse, resulting in a supernova explosion . 35. And neither type of burning, by itself, can easily explain what astronomers have seen in supernova explosions . 36. The ultimate fate of all massive stars is a core collapse and some sort of supernova explosion . 37. But every now and then, we do see a significant change in the skies _ a supernova explosion . 38. Its outer layers probably were blown away by the supernova explosion that gave birth to the black hole. 39. Because they are so faint and are obscured by Earth's atmosphere, very distant supernova explosions are rarely seen. 40. A supernova explosion at a distance of 26 light years will reduce the ozone column density by half.
