G1.9+0.3: The last galactic supernova

When was the last supernova in our galaxy?

This questions sounds straightforward but it’s actually a little bit convoluted to answer. But just a little, so sit back and let’s talk about a science communication mistake, light travel time, and what happens when an entire star explodes. Sometimes two.

So. I recently wrote about a stellar explosion 900 years ago called Supernova 1181, and how astronomers have finally identified the expanding debris from that catastrophic event.

When I wrote about...