First, I would like to point out, yes, our sun does not have enough mass to be a candidate for Supernova, this is a scenario were our sun is though, and after the various life cycle stages of the sun and whether or not life managed to survive or not on the planet, The Sun goes of as a Supernova, it is 1 AU from an Earth-like planet, or equivalent to 1 AU from a massive star, would the planet still be standing or would it be obliterated from the face of the Galaxy?

Here are some of the links that I have been looking through but could not find an answer for:

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    $\begingroup$ On this site, we generally don't answer questions about impossible hypothetical scenarios. You could change your question to ask about an Earth-like planet orbiting a star that is massive enough to go supernova. However, such a star would be much hotter than our Sun, so its Goldilocks Zone would be further than 1 AU. $\endgroup$ – PM 2Ring Aug 13 at 23:07
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    $\begingroup$ Okay, I changed some detail to make it an earth-like planet, and that it would be the distance equivalent to 1 au from a massive star. $\endgroup$ – C. Jordan Aug 13 at 23:12

One way of estimating this is to look at how much energy could be received by the planet. At distance $d$ it takes up $r^2/4 d^2$ of the sky as seen by the supernova. So for a $10^{44}$ J blast that is about $4.5444\times 10^{34}$ J.

The gravitational binding energy of Earth is about $2\times 10^{32}$ J. So we have about 227 times as much energy as is needed to separate all pieces of the planet to infinity. It is also a few thousand times the energy needed to heat up an Earth-mass of iron from 0K to vaporisation. So, yes, it looks like it could well obliterate the planet.

Whether it actually does so is a complex question of how protected the evaporating planet is by its plasma sheath during the explosion. Given that actual terrestrial exoplanets in close orbits at 2000K may lose an Earth mass per gigayear it looks plausible that at least slower scenarios can vaporise planets.

  • $\begingroup$ More than 99% of the energy released in a (type II) supernova is in the form of neutrinos that would not be absorbed by the planet. Fortunately, the energy released in a type II SN is actually $10^{46}$ J, so your conclusion probably stands. $\endgroup$ – Rob Jeffries Aug 14 at 19:24
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    $\begingroup$ @RobJeffries - I was using the non-neutrino energy for the calculation for this reason. $\endgroup$ – Anders Sandberg Aug 14 at 20:41
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    $\begingroup$ Say so then. And what you assume about the forms of energy released and how much can be absorbed by the planet. $\endgroup$ – Rob Jeffries Aug 14 at 20:53

If the sun were a much larger and more massive star of the kind that supernovae are made of, the Earth at 1AU would be in pretty poor shape anyway, a scorched cinder. Life would never even get started, never mind survive. In the supernova explosion the surface of the Earth would be blasted away and whatever was left propelled at great speed out of the solar system, and pretty much obliterated from the galaxy. The actual fate of the Earth is more interesting, as it is really going to happen in about 5 billion years time. When the sun becomes a red giant, the Earth will be scorched to a cinder and all life on Earth will cease. After expelling some mass, the sun will finally become a white dwarf about the size of Earth.

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    $\begingroup$ The question is asking about the “blasting away”, which you just assume to be the case. A supernova explosion could equally be an awful lot of very hot matter going past very fast, so that you don’t have time to be fried. And, star-stuff being so tenuous, it might not even thump you much when it hits. That is the question. Pass your hand rapidly through a gas flame and you’ll singe a few hairs, no more. $\endgroup$ – Martin Kochanski Aug 14 at 7:08
  • $\begingroup$ You wouldn't be fried because you wouldn't be there, neither would anybody else. I thought I made that clear. If you miracujlously were there, you'd have been fried long before a star massive enough to go supernova exploded. $\endgroup$ – Michael Walsby Aug 14 at 8:57
  • $\begingroup$ I made a few changes because of the conditions this site's rules require, so it is an Earth-Like Planet and the Star would be a massive enough to be reach supernova and it's Goldilock Zone would be equivalent to that of our solar system $\endgroup$ – C. Jordan Aug 14 at 14:47

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