Final answer:
From Supernova SN 1987A, a total of 19 neutrinos were detected on Earth by neutrino telescopes in Japan and under Lake Erie. These observations provided significant insights into the nature of supernovae and the behavior of neutrinos, including their mass and interactions with matter.
Step-by-step explanation:
In 1987, the event known as Supernova SN 1987A illuminated the skies and provided a rare opportunity for scientists to observe and detect neutrinos here on Earth. Neutrinos are elusive subatomic particles that rarely interact with matter, making their detection a notable feat. These particles were emitted massively from the supernova, with an estimated 1058 being released overall. Despite the staggering number, only 19 of these neutrinos were detected by the neutrino telescopes located in a deep mine in Japan and under Lake Erie in the Northern Hemisphere.
The detectors, composed of thousands of tons of purified water and hundreds of light-sensitive detectors, captured the neutrinos as they passed through the Earth. It's fascinating to note that about 30 billion neutrinos from the supernova passed through each square centimeter of Earth's surface, but their interactions with matter are so rare that just a single nucleus in each person would have experienced such an interaction, passing unnoticed and posing no biological effects.
The detection of neutrinos from SN 1987A is significant not only for the direct observation of such particles but also for confirming our understanding of the immense energy release and element formation during supernova events, which the later gamma-ray detection associated with radioactive decay further corroborated. This detection also plays a role in scientific discussions concerning the mass of neutrinos, setting upper limits based on their travel speed relative to light.