Starship Asterisk*

I learned about the forum when I asked Dr. Nemiroff a question and he referred me here. So I'll ask it here.

The discussion of today's APOD didn't mention the distance to A.C. which I see is about 8,000 ly. That's a good distance and, hopefully, safe when the supernova occurs.

Is there an accepted distance that's considered safe for us and our civilization?

"referred me" is one way to put it- a better would be that he didn't answer my question with even a form letter saying thanks for enjoying APOD but just sent the link. But hey, I understand that he's a busy guy.
Anyway, this was my question:

In the description, you say "Eta Carinae may be about to explode. But no one knows when - it may be next year, it may be one million years from now ". My question is this: isn't the star very far away, and so isn't what we see of the star in the distant past? Are we just speculating on what may have already become of the star?

First, yes I think we are talking about an event which could already have happened. Of course we'll know about it when the light gets here, ~ 8,000 years after it happen(s?d?).

I looked at the FAQ for this group and it led me to a possible answer to my question. It's at
http://stupendous.rit.edu/richmond/answers/snrisks.txt
but boils down to, one kind of supernova would probably have to be within about 30 ly, but a more energetic type could harm us from farther away. This suggests we are quite safe from supernovas for the forseeable future.
A little additional discussion is at
http://imagine.gsfc.nasa.gov/docs/ask_a ... 0521a.html

Thought this old thread might help the discussions going on now.

Norval

Good idea. Go here.