Neutrino footprint from a celestial firework, SN1987A

5 November 1997 

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When the supernova SN1987A appeared in the southern skies ten years ago, the light was preceded by several hours by invisible messengers - the ghostly particles known as neutrinos. Only about 1 per cent of the supernova's energy appeared in the optical firework display; the remainder swept into space as neutrinos, with as many as 50 billion passing through each square centimetre of the Earth's surface. The great majority passed straight through the Earth, but nearly 20 were trapped in two water-filled underground detectors, IMB and Kamiokande. The image shows the pattern of light created by the interaction of the one the supernova neutrinos in the IMB (Irvine-Michigan-Brookhaven) detector. The straight lines mark the walls of the detector, 20 m across, while the yellow circle marks the location of phototubes that picked up light (Cherenkov radiation) emitted by a charged particle from the neutrino's interaction.

Credit: University of Califonia, Irvine / University of Michigan

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