So if it blew up 639.9 million years ago, we should be seeing it right about.............now!
The article says it’s 640 light years away, not 640 million LY.
It took 14 posts.
Whenever we see it, the news is approximately 640 years old, since it took that long for the light of the blast to reach us.
When it does happen, it’ll be extremely old news. If it happens in our lifetime the event itself will have taken place prior to Columbus being born.