This is less a real post than a promise for the future: I have several projects brewing this week and next, both on this site and elsewhere in the wild world of the web. (I may even have a regular post here today, but don’t count on it.) Two of the projects are sooper seekrit for the time being, but the third is another podcast I’m recording for 365 Days of Astronomy, to be broadcast on June 13.
In the meantime, have a look at this image from today’s Astronomy Picture of the Day: a supernova explosion in the beautiful spiral galaxy M51. The two alternating snapshots are “before” and “after” pictures, showing how quickly supernovas occur — and how bright they are! For a brief period of time this explosion is brighter than anything else in its host galaxy, and actually appears brighter than many of the stars in the foreground, which lie in our own galaxy –a lot closer to us than M51.
Galileo's Pendulum 
2 responses to “Explosions in the Sky”
A comment for non-astronomers: Probably it was Carl Sagan who pointed out that the iron in your blood cells was formed in the heart of a supernova. This is a profound statement. In the beginning (the Big Bang), there was only hydrogen and helium, and traces of a few other elements. All of the heavier elements were formed by stellar evolution, and were blasted out into the interstellar environment by supernovae. So supernovae are not just fireworks in the sky for our amusement, they are a key feature of the creation of our Earth.
Indeed, Carl Sagan pointed out that we are star-stuff, although he surely wasn’t the first to recognize that fact. Nearly every atom of our body has passed through a supernova!