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Today is the Fourth of July, a national holiday in the U.S. where we celebrate the signing of the Declaration of Independence (we didn’t actually win our independence until 1783, depending on how you look at it).
It’s traditional to celebrate with fireworks, which I’ve always enjoyed (though some people are making the case that we should be aware of people—and pets—who don’t). But as an astronomer, my idea of fireworks is maybe somewhat more expansive than most folks …
Like, the explosion of an entire star. Called a supernova, they’re among the most violent events the Universe has to offer. The amount of energy they emit can be equal to the total amount of energy the Sun emits over its entire lifetime. The closest example is the Crab Nebula, seen above. Want a fun little bit of cosmic trivia to astound your friends? The light from this explosion reached Earth in the year 1054 … on July 4.
Anyway, the good news is that these ridiculously huge events tend to happen very far away. But what if one were a lot closer? Well, if it got close enough, we’d be in trouble. I wrote a chapter in my book Death From the Skies! about that.
But I also talked to science communicator Rose Eveleth about what would happen if a supernova were too close for comfort on her podcast Meanwhile in the Future. Also appearing is my friend and astrophysicist Katie Mack.
That was fun. She starts off each episode with a little vignette talking about some event in the future, then uses that as a springboard to talk about the science of an event. Clever.
I wrote more about the Crab in a recent post, and it turned out to be a little more poetic than I expected. But hopefully, it’ll give you an impression of the cosmic forces out there, ones which craft the Universe we live in.
If you’re celebrating July Fourth today, have fun! But remember, have some perspective. The fireworks you’re watching could be a lot, lot bigger.