Today’s factismal: There are 30 supernovae every second in the Universe but only eight of them have ever been close enough to see with the naked eye.
Almost a thousand years ago, astronomers across the world all saw something amazing: a bright, new star in the heavens. The new star was so bright that it could be seen in the daylight for 23 days and was clearly visible at night for nearly two years. It would take five hundred years before astronomers gave the phenomenon a name and another four hundred years before we understood that we had seen the death of a star in an explosion larger than any ever seen before; we had seen history’s first recorded supernova. Since then, we’ve seen eight more even though astronomers estimate that there are 30 new supernovae every second. The reason that we’ve seen so few is because space is so vastly, hugely, mindboggling big that, unless it is very close, even the brightest explosion is too dim to see without a very strong telescope.
But that’s not the most amazing thing about the supernova of 1054. The most amazing thing is that the folks who wrote the most about it were also the people who developed fireworks. And the amazing thing about that is that the same physical processes that give fireworks their color is what tells us the composition of a star. For example, if you see a red firework, you know that they put strontium or lithium in the mix. A blue firework means copper. A bright yellow can only come form sodium in the mix. And adding calcium gives orange. So the color of the fireworks tell us what they are made of. Similarly, the color of a star tells us what chemicals are present in the star.
What is cool about that is that the chemicals that are present in the star tell us a lot about when it formed. Because the heavier elements are formed in supernovae explosions, the first stars had nothing higher than helium in them; when they died, they added a little of the heavier elements to the universe, seeding space with the elements needed for the next generation of stars. Those had more of the lighter elements and very few of the heavier ones. When they became supernovae, they increased the amount of higher elements still further. So, by looking at the elements that are present in a star, we can tell about when it formed.
Naturally, that means that there is a citizen science opportunity. The folks at Stellar Classification Online Public Exploration (SCOPE) need your help in looking at the colors given off by stars. You’ll be able to determine the temperature and the composition of the stars using their handy-dandy online app; even better, because you’ll be comparing your star to one with a known composition and temperature, you won’t need to deal with any of the tedious details. So celebrate this Fourth of July by looking the biggest fireworks display ever!