Science: A Wonder in the Southern Sky

While scanning some routine sky photographs at Las Campanas Observatory in Chile last week, Astronomer Ian Shelton felt a surge of excitement. In an exposure he had taken just hours before with one of the observatory's small telescopes was a bright spot that had not appeared in older pictures. Stepping out into the clear mountain air of the Chilean coastal range, the University of Toronto scientist reverted to a technique now used only rarely by professional stargazers: he looked up at the sky. There, in the fuzzy patch of light known as the Large Magellanic Cloud, was the spot. Says Shelton: "For more than three hours, I tried several logical explanations. It took me a long time to actually accept that what I had just seen was a supernova."

But a supernova it was, a massive star dying in an explosion so violent that for a few weeks it will outshine hundreds of millions of stars put together. Its home, the Large Magellanic Cloud, is a satellite galaxy, or island of stars, that lies just beyond the fringes of our Milky Way galaxy, some 170,000 light-years from earth. (A light-year, the distance light travels in a year, is roughly 6 trillion miles.)

At that distance, close by astronomical standards, it could be one of the brightest stars in the sky when it peaks in intensity, perhaps as early as next week. (While it is clearly visible in the Southern Hemisphere, even Hawaii is too far north for much of a view.) The star will be the brightest supernova observed since 1604 and the only one visible to the naked eye since 1885. Says University of Chicago Astronomer W. David Arnett: "This is probably the most important thing that's happened in astronomy since 1604. It finally gives us a way of testing ideas about how stars and galaxies work and how abundances of heavy elements are created." The reason for the superlatives being expressed by Arnett and other astronomers is that this is $ the first supernova close enough to the earth to be scrutinized in fine detail by modern astronomical techniques.

Realizing the importance of his discovery, Shelton moved quickly to contact the International Astronomical Union's telegram service in Cambridge, Mass., the world's clearinghouse for announcements of new comets, asteroids and other transient astronomical phenomena. Shelton was the first to report the supernova, but, according to Service Director Brian Marsden, a New Zealand amateur astronomer named Albert Jones also spotted it that night. By the end of the day the service had sent telegrams announcing the supernova, officially designated 1987A, to some 150 institutions around the world.