Killer Supernovae? by Nathalie Ouellette

Kepler's supernova remnant. Image credit:  NASA ,  ESA , R. Sankrit and W. Blair (Johns Hopkins University).

Kepler's supernova remnant. Image credit: NASAESA, R. Sankrit and W. Blair (Johns Hopkins University).

This month, we'll be delving into supernovae! Some scientists are studying the possible effect such a cataclysmic event might have on Earth, were it to occur at close enough proximity. A straightforward measurement of how likely a supernova is within a distance D from Earth is given by this distance divided by 32.6 lightyears, all cubed — or (D / 32.6 lyr)^3. This is how likely such an event is over the span of one billion years. Trust me, it isn’t very likely to get something significant close by once you do the math. Furthermore, the effects of a supernova don’t only depend on its distance from Earth, but also on its type — which is strongly correlated to the amount of energy it outputs. 

A significant, and significantly close-by supernova may have occurred approximately 450 million years ago. The gamma raysemitted by such a supernova would have been so powerful that they would have stripped a large part of our planet’s ozone layer. This might have been the cause of the Ordovician-Silurian extinction — the third largest extinction ever to be recorded — which resulted in the extinction of about half of the planet’s species. Geez… Killer comets, supernovae shooting death rays. Maybe my monthly trivia should lighten up a bit!

There are about a trillion articles out there on the world wide web on this topic, ranging from very interesting and thought provoking to ridiculously bad faux-science fear mongering. Here’s a nice starting point, via Discovery News.

If you find yourself navigating the intertubes for more info, tread carefully and read critically, as always!