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How do they know that the pillars have been destroyed if the light will reach us in 1000 years time?

The "Pillars of Creation" from the Eagle Nebula. Evidence from the Spitzer Telescope suggests that the pillars may already have been destroyed by a supernova explosion, but the light showing us the destruction will not reach the Earth for another millennium.

Article explaining that we won't see the effects in another 1000 years

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    $\begingroup$ They don't know. Read such articles carefully. This article is at least honest (others not, so much): "the pillars may already have been destroyed", and later "Astronomers speculate that the supernova's shock wave ...". Note the words indicating this is a conjecture rather than a known fact. $\endgroup$ – David Hammen Sep 7 '18 at 12:11
  • $\begingroup$ The quote is from wikipedia by the way. $\endgroup$ – ACV Sep 7 '18 at 13:52
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    $\begingroup$ Hi, ACV, welcome to the site. I think this is a possible duplicate of astronomy.stackexchange.com/q/8208/2153. $\endgroup$ – HDE 226868 Sep 7 '18 at 15:27
  • $\begingroup$ You are right. I'll close this one $\endgroup$ – ACV Sep 7 '18 at 15:55
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It's a bit hard to say for sure as the article isn't terribly clear, but what I think they're saying is that there is a dust cloud to the upper right side of the Pillars (as viewed in the photo.) They further say that the dust cloud shows evidence of a supernova shock wave passing through it, presumably from the upper right and presumably from a supernova. (Note that the supernova was not observed, and they don't report on a remnant being visible.) Then they say that when that shockwave reaches the Pillars, the Pillars will be destroyed. They estimate that that will be observed from Earth in the next thousand years or so. (Note that they don't report measuring of the speed of the shockwave -- I'm guessing they assume it's moving as typical speeds.) Since the Pillars are about 7000 light years away, than means that this destruction "already" has happened.

There's nothing impossible about all this, but it looks like speculation based on limited actual facts. It's also worth mentioning that what you see on the web went through a press office, and press offices are paid for doing publicity, not for doing science. The quality of what a press office posts (already undermined by being a popularization, which is hard to do well even when you're trying to be accurate) is frequently biased by a publicity-at-any-cost attitude. Always read press releases and the like with your sceptometer turned up to High.

Personally, I'd like to see stronger evidence for the existence of the shockwave, and evidence that the shockwave will actually disrupt the Pillars. (The Pillars are considerably denser than the medium around them, and so may be resistant.)

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  • $\begingroup$ OK so they mean the desctruction starting is already visible in pictures, but it only started and the actual destruction of the pillars will reach us later.. $\endgroup$ – ACV Sep 7 '18 at 13:55
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    $\begingroup$ Read the articles carefully, ACV. It means that one interpretation of what has been seen is that the destruction from a nearby supernova had started 7000 years ago. There are other interpretations (also speculative) that say something less drastic was happening 7000 years ago. Also keep in mind that when we look at objects in space that what we are seeing now happened some time ago. Astronomy inherently looks into the past, with how far back in the past depending on how long it took light to travel from the event in question to us. $\endgroup$ – David Hammen Sep 7 '18 at 14:54
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    $\begingroup$ Agree with @David Hammen. There definitely are bright, large, hot, young stars in the vicinity, and we would expect a number of then to go supernova now +/- 500Kyears. And the radiation (primarily the UV) from those young stars is almost certainly responsible for the existing erosion of the nebula which produced the Pillars. The only new thing I saw here was the idea that there was a supernova shockwave moving towards the Pillars which was strong enough to destroy them. $\endgroup$ – Mark Olson Sep 7 '18 at 15:13

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