On this day in 1987, the supernova SN 1987A exploded into view of Earth, having travelled across space from a galaxy 168,000 light-years away. It was discovered by 30-year-old astronomer Ian Shelton, who was—at the time—listening to Pink Floyd’s psychedelic classic “The Wall” late at night while studying photographic plates of space.
Shelton was working at the University of Toronto’s observatory in Chile, in the foothills of the Andes mountains, and was not searching for supernovas in particular. However, he spotted an extraordinarily bright spot on one of the photographic plates, which showed the Tarantula Nebula in the Large Magellanic Cloud—a dwarf galaxy adjacent to our own Milky Way—and wondered what it could be. “I didn’t call it a supernova in my head at that point,” Shelton said, “I just thought, this thing is bright.”
In fact, it turned out to be the brightest supernova of the 20th century. When Ian Shelton walked out of the observatory, he was surprised to see that the object was even visible to the naked eye. It was the first time that anyone could observe a supernova without a telescope since 1604 (which was, of course, prior to the invention of the telescope), when one occurred within the Milky Way itself.
A supernova is a star that has reached the end of its life and exploded, ejecting most of its mass and illuminating the universe with an intense brightness—the biggest supernovas are able to temporarily outshine entire galaxies, and often radiate more energy in one blast than the Sun will radiate in its entire lifetime. They are also the primary source of heavy elements—such as sulphur, silicon, and iron—in the universe. When SN 1987A exploded, colossal quantities of gases, debris, and space dust erupted outwards, and then collided together as the star collapsed inwards, illuminating the Universe.
Although SN 1987A was one of the most impressive galactic spectacles of the modern age, and still one of the most studied objects in the southern sky, it is not without its mysteries. Astronomers have identified it as a core-collapse supernova, and this sort of phenomenon should always result in the creation of a neutron star—a stellar remnant resulting from the gravitational collapse of a massive star. However, ever since the supernova’s appearance in 1987, scientists have been searching for its collapsed core without any success. The Hubble Space Telescope has regularly photographed the supernova for over two decades now, and still hasn’t spotted the neutron star. Perhaps it is shrouded in dense dust clouds, perhaps it somehow formed into a pulsar, or perhaps it collapsed into an unusually dim black hole; but to this day, no one is sure of exactly what happened after SN 1987A exploded.
Photo Credit: The Hubble Heritage Team (AURA/STScI/NASA)
Photo Caption: The brilliance of Supernova 1987A on 23 February 1987 was so bright, it could be seen with the naked eye.