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There are historical reports about supernovae where they were visible during the day for a few weeks. I guess it would look just like another bright star. Makes

There are historical reports about supernovae where they were visible during the day for a few weeks. I guess it would look just like another bright star. Makes me wonder what the minimum safe distance is.

duxup 7y ago
Yean I was thinking the same thing. How spectacular of a view could you get from an earth like planet ... and still not have any ill effects? Could it be a huge spectacular thing reaching across the entire sky, or would by that stage you be in real trouble?
- svachalek 7y ago
  Interesting question. My off-the-top instinct would be to say any explosion that looks bigger than the sun is probably delivering more radiation than the sun and that would be bad news. But that’s without doing any math. (Also brings to mind the book Dhalgren.)
  - danparsonson 7y ago
    Somewhat :-) Supernovae are relatively easy to spot because they usually outshine their entire host galaxy.
- marcosdumay 7y ago
  The size of the visible object is determined by it's real size and distance... That's to say, no it will never look big. But it can look very bright, so it illuminates the sky. It would certainly be interesting to have an object so shiny that it creates a glowing halo around it, but I'm not sure it would be safe to look at that halo.
- SiempreViernes 7y ago
  If you want to see the shock front move on something like a second timescale, I'm pretty sure you need to be close enough to be in real trouble. Typical expansion velocity is on the order of 10 000 km/s radially, so you get 20 kkm increase in diameter per second. For safety then, 20 kkm should correspond to a barely perceptual angular change, which wikipedia tells me is around 1 arc minute. So if you are close enough to just see the shock front move, you have about an hour until it gets to you, and if you want to avoid being overtaken you need to be able to move at ~ 10 kkm/s.
kaonwarb 7y ago
See https://en.wikipedia.org/wiki/SN_1006 https://en.wikipedia.org/wiki/SN_1006 - "likely the brightest observed stellar event in recorded history." Observed in 1006 AD "across the modern day countries of China, Japan, Iraq, Egypt, and the continent of Europe, and possibly recorded in North American petroglyphs."

duxup 7y ago

Yean I was thinking the same thing. How spectacular of a view could you get from an earth like planet ... and still not have any ill effects? Could it be a huge spectacular thing reaching across the entire sky, or would by that stage you be in real trouble?

svachalek 7y ago
Interesting question. My off-the-top instinct would be to say any explosion that looks bigger than the sun is probably delivering more radiation than the sun and that would be bad news. But that’s without doing any math. (Also brings to mind the book Dhalgren.)
- danparsonson 7y ago
  Somewhat :-) Supernovae are relatively easy to spot because they usually outshine their entire host galaxy.
marcosdumay 7y ago
The size of the visible object is determined by it's real size and distance... That's to say, no it will never look big. But it can look very bright, so it illuminates the sky. It would certainly be interesting to have an object so shiny that it creates a glowing halo around it, but I'm not sure it would be safe to look at that halo.
SiempreViernes 7y ago
If you want to see the shock front move on something like a second timescale, I'm pretty sure you need to be close enough to be in real trouble. Typical expansion velocity is on the order of 10 000 km/s radially, so you get 20 kkm increase in diameter per second. For safety then, 20 kkm should correspond to a barely perceptual angular change, which wikipedia tells me is around 1 arc minute. So if you are close enough to just see the shock front move, you have about an hour until it gets to you, and if you want to avoid being overtaken you need to be able to move at ~ 10 kkm/s.

kaonwarb 7y ago

See https://en.wikipedia.org/wiki/SN_1006 https://en.wikipedia.org/wiki/SN_1006 - "likely the brightest observed stellar event in recorded history." Observed in 1006 AD "across the modern day countries of China, Japan, Iraq, Egypt, and the continent of Europe, and possibly recorded in North American petroglyphs."