# How close does a star have to be to kill us? Can it happen? **URL:** \ **Category:** Factual Questions\ **Created:** [August 17, 2001, 7:50pm UTC](https://boards.straightdope.com/t/how-close-does-a-star-have-to-be-to-kill-us-can-it-happen/76797 "2001-08-17T19:50:18Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![bernse](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@bernse](https://boards.straightdope.com/u/bernse)\ **Post date:** [August 17, 2001, 7:50pm UTC](https://boards.straightdope.com/t/how-close-does-a-star-have-to-be-to-kill-us-can-it-happen/76797/1 "2001-08-17T19:50:18Z")
The thread about Armageddon got me thinking about this (I would like to link but sorry, I forgot to copy the URL) ☹ If a “nearby” star can go Nova and kill us: 1. How far does a star have to be until it doesn’t matter to us if it goes Nova or not… in other words, when does the star _not_ become a worry? 100 Light years, 200? 300? 2. Are there any stars close enough to us that are capable to go Nova and kill us? 3. If so, are they old enough to make it a concern for the “near” (I know this is a _very_ loose term in cosmic terms) future? In other words, being that even if a star went Nova we wouldn’t know until the light hit us (which would be several years) are some showing “early” signs that its main sequence is on the downward trend? 4. Is there anything else that a star can do (or someother cosmic phenomena outside of our solar system) that can cause us harm? Thanks! ---
**Author:** ![Phobos](https://avatars.discourse-cdn.com/v4/letter/p/3d9bf3/32.png) [@Phobos](https://boards.straightdope.com/u/Phobos)\ **Post date:** [August 17, 2001, 8:04pm UTC](https://boards.straightdope.com/t/how-close-does-a-star-have-to-be-to-kill-us-can-it-happen/76797/2 "2001-08-17T20:04:35Z")
I assume you mean “supernova” (which is very different than a “nova” even though the names are similar…a nova is a sudden brightening whereas a supernova is an explosion). (1) We’d be safe from the explosion of a star a few hundred light years away, but I’m not sure what would happen when the ejected material eventually reached us. [http://itss.raytheon.com/cafe/qadir/q2742.html](http://itss.raytheon.com/cafe/qadir/q2742.html) (2) Not that I know of. (3) Betelgeuse is fairly close and is about to go supernova - but I think we’ll be ok. [http://www.astro.uiuc.edu/~kaler/sow/betelgeuse.html](http://www.astro.uiuc.edu/~kaler/sow/betelgeuse.html) (4) Colliding neutron stars or black holes (i.e., dead stars) would send high energy rays (gamma?) our way…could be strong enough to cause damage depending on how close they are. AFAIK, none of the closest ones are expected to do this any time soon. ---
**Author:** ![slortar](https://avatars.discourse-cdn.com/v4/letter/s/6bbea6/32.png) [@slortar](https://boards.straightdope.com/u/slortar)\ **Post date:** [August 17, 2001, 8:06pm UTC](https://boards.straightdope.com/t/how-close-does-a-star-have-to-be-to-kill-us-can-it-happen/76797/3 "2001-08-17T20:06:15Z")
The primary of alpha centauri is pretty big. If that went nova, we’d be hurting big time. :eek: ---
**Author:** ![bernse](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@bernse](https://boards.straightdope.com/u/bernse)\ **Post date:** [August 17, 2001, 8:17pm UTC](https://boards.straightdope.com/t/how-close-does-a-star-have-to-be-to-kill-us-can-it-happen/76797/4 "2001-08-17T20:17:48Z")
Sorry, I did indeed mean “supernova”. Duh. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [August 17, 2001, 9:44pm UTC](https://boards.straightdope.com/t/how-close-does-a-star-have-to-be-to-kill-us-can-it-happen/76797/5 "2001-08-17T21:44:54Z")
on [space.com](http://space.com) I recall a star about to go hypernova (basiaclly hteir phrase for a really big supernova) fairly close to us. They perdict that we’d be safe on the ground but it could knock out out sats and fry people in the ISS. ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [August 17, 2001, 10:10pm UTC](https://boards.straightdope.com/t/how-close-does-a-star-have-to-be-to-kill-us-can-it-happen/76797/6 "2001-08-17T22:10:09Z")
On the other hand, our own Sun can let loose a Solar Flare or Solar Prominence that could reach far enough into space to fry the Earth. Nice day, huh? 🙂 ---
**Author:** ![Reeder](https://avatars.discourse-cdn.com/v4/letter/r/c6cbf5/32.png) [@Reeder](https://boards.straightdope.com/u/Reeder)\ **Post date:** [August 17, 2001, 10:16pm UTC](https://boards.straightdope.com/t/how-close-does-a-star-have-to-be-to-kill-us-can-it-happen/76797/7 "2001-08-17T22:16:08Z")
Some day…in the far future. Our little sun itself will grow to be a red giant and the earth will be orbiting inside it…so to speak. Something to look forward to eh? ---
**Author:** ![bernse](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@bernse](https://boards.straightdope.com/u/bernse)\ **Post date:** [August 17, 2001, 10:32pm UTC](https://boards.straightdope.com/t/how-close-does-a-star-have-to-be-to-kill-us-can-it-happen/76797/8 "2001-08-17T22:32:45Z")
> [@](#): > > \*Originally posted by Bosda Di’Chi of Tricor \* > \*\*On the other hand, our own Sun can let loose a Solar Flare or Solar Prominence that could reach far enough into space to fry the Earth. > > Nice day, huh? 🙂 \*\* Really? A flare can reach that far? I had no idea. ---
**Author:** ![Clueless](https://avatars.discourse-cdn.com/v4/letter/c/35a633/32.png) [@Clueless](https://boards.straightdope.com/u/Clueless)\ **Post date:** [August 17, 2001, 11:58pm UTC](https://boards.straightdope.com/t/how-close-does-a-star-have-to-be-to-kill-us-can-it-happen/76797/9 "2001-08-17T23:58:51Z")
> [@](#): > > Betelgeuse is fairly close and is about to go supernova - but I think we’ll be ok. How do we know it hasn’t gone supernova yet? Maybe it has gone supernova but the light hasn’t reached us yet. 🙂 ---
**Author:** ![Manduck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/manduck/32/256_2.png) [@Manduck](https://boards.straightdope.com/u/Manduck)\ **Post date:** [August 18, 2001, 1:56am UTC](https://boards.straightdope.com/t/how-close-does-a-star-have-to-be-to-kill-us-can-it-happen/76797/10 "2001-08-18T01:56:56Z")
It depends. Is the star O.J. Simpson? 😃 ---
**Author:** ![thinksnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thinksnow/32/2849_2.png) [@thinksnow](https://boards.straightdope.com/u/thinksnow)\ **Post date:** [August 18, 2001, 4:21am UTC](https://boards.straightdope.com/t/how-close-does-a-star-have-to-be-to-kill-us-can-it-happen/76797/11 "2001-08-18T04:21:10Z")
> [@](#): > > \*\*bernse > > > [@](#): > > > > Bosda Di’Chi of Tricor \*\* > > On the other hand, our own Sun can let loose a Solar Flare or Solar Prominence that could reach far enough into space to fry the Earth. > > Really? A flare can reach that far? I had no idea. I was under the impression that the largest recorded flare, a couple of decades ago, dirupted some satellites, airline comm and the Canadian power grid, but that was about it. Actually, just checking for sites, I found that we had the largest recorded flare this [April](http://www.cnn.com/2001/TECH/space/04/04/solar.storm/). The article comments: > [@](#): > > Directed toward Earth, such storms can disrupt satellite communications and power grids and produce dramatic aurora displays in the northern and southern latitudes. ---
**Author:** ![bernse](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@bernse](https://boards.straightdope.com/u/bernse)\ **Post date:** [August 18, 2001, 2:33pm UTC](https://boards.straightdope.com/t/how-close-does-a-star-have-to-be-to-kill-us-can-it-happen/76797/12 "2001-08-18T14:33:58Z")
I know the electromagnetic effects can definetly effect us. When “fry” was mentioned, I was thinking the actual “flame” or “heat”.