Comet Ison... And We're Totally Doomed!

Hola,
After I posted that devastating portrayal of the state of the ‘average person’s’ knowledge of our cosmos last week. I figured I’d write a post or two regarding just what lurks out and about in our stellar neighborhood and what it actually is. That way, should you ever get stopped by Jay Leno on the street and asked what a comet it, you won’t be forced to tell him that it’s ‘A star that, due to physics, has had its barometric pressure rise and causes it to spin’.*
So, I’ve been excited for...