Are the Stars Still There?

[stewartt]

&nbsp;I'm not a scientist, nor even an amateur stargazer, but this is a<br />question I've been struggling with.&nbsp; Are the stars still there?<br />&nbsp;&nbsp;&nbsp;For example, I read a bit on this site about the possiblity that<br />there may be parts of our universe that we've not yet seen, simply<br />because the light from them hasn't had time to reach us yet.&nbsp; OK, I can<br />understand that.<br />&nbsp;&nbsp;&nbsp;But, what about the stars that we see at night?&nbsp; I seem to recall<br />that the nearest star to Earth is about 2.5 million light years away.<br />So, what if that star burned out a million years ago.&nbsp; We would still be<br />seeing the light from this star for another 1.5 million years.&nbsp; And that<br />is just the closest one!<br />&nbsp;&nbsp;&nbsp;So, is it theoretically possible that ALL of the starlight we see is<br />coming from stars that have in fact burned out, and are not even really<br />there anymore, and that all we're seeing is the light that left them<br />before they burned out?<br />&nbsp;&nbsp;&nbsp;Any logical reply in words that I can comprehend, or a reference to<br />somewhere I can read about this would be much appreciated.&nbsp; Thanks!

 

[centsworth_II]

Astronomers know quite a lot about the various types of stars, their development stages, and lifespan.&nbsp; They can tell if the stars they are looking at are young, middle age or old, and about how much longer they have to live.&nbsp; If the estimated time left for a star is greater than the distance from us in light-years then that star is most likely still there. <div class="Discussion_UserSignature"> </div>

 

[eburacum45]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;&nbsp; I seem to recallthat the nearest star to Earth is about 2.5 million light years away.So, what if that star burned out a million years ago.&nbsp; We would still beseeing the light from this star for another 1.5 million years.&nbsp; And thatis just the closest one!&nbsp;</DIV></p><p>&nbsp;</p><p>Nope, it is only 4.5 light years away. Very few of the stars you can see in the sky are more than a few hundred light years away; the furthest star that can be seen with the naked eye is a few thousand light years away.</p><p>Perhaps one or two of the stars in the sky that are visible with the naked eye have disappeared since the light that we see left them; Betelgeuse, possibly, Rho Cassiopeia, one or two others. But the great majority of the stars we can see with the naked eye are still there.</p> <div class="Discussion_UserSignature"> <p>---------------------------------------------------------------</p><p>http://orionsarm.com  http://thestarlark.blogspot.com/</p> </div>

 

[nimbus]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;I'm not a scientist, nor even an amateur stargazer, but this is aquestion I've been struggling with.&nbsp; Are the stars still there?&nbsp;&nbsp;&nbsp;For example, I read a bit on this site about the possiblity thatthere may be parts of our universe that we've not yet seen, simplybecause the light from them hasn't had time to reach us yet.&nbsp; OK, I canunderstand that.&nbsp;&nbsp;&nbsp;But, what about the stars that we see at night?&nbsp; I seem to recallthat the nearest star to Earth is about 2.5 million light years away.So, what if that star burned out a million years ago.&nbsp; We would still beseeing the light from this star for another 1.5 million years.&nbsp; And thatis just the closest one!&nbsp;&nbsp;&nbsp;So, is it theoretically possible that ALL of the starlight we see iscoming from stars that have in fact burned out, and are not even reallythere anymore, and that all we're seeing is the light that left thembefore they burned out?&nbsp;&nbsp;&nbsp;Any logical reply in words that I can comprehend, or a reference tosomewhere I can read about this would be much appreciated.&nbsp; Thanks! <br /> Posted by stewartt</DIV><br />The nearest star is Alpha Centauri (three stars in fact) ~25 trillion miles or +-4.3 light years away. &nbsp;The&nbsp;nearest&nbsp;galaxy is Andromeda, ~2.5 million light years away. &nbsp;You've got the concept of light travel delay,&nbsp;but I'll&nbsp;let someone with a better grasp of the effect of space expansion and astronomical objects' life expectancies say what's possible and what's not, with regards to which objects we see not being as we see them.</p><p>http://en.wikipedia.org/wiki/List_of_nearest_galaxies</p><p>http://en.wikipedia.org/wiki/List_of_nearest_stars</p> <div class="Discussion_UserSignature"> </div>

 

[neilsox]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;I'm not a scientist, nor even an amateur stargazer, but this is aquestion I've been struggling with.&nbsp; Are the stars still there?&nbsp;&nbsp;&nbsp;For example, I read a bit on this site about the possiblity thatthere may be parts of our universe that we've not yet seen, simplybecause the light from them hasn't had time to reach us yet.&nbsp; OK, I canunderstand that.&nbsp;&nbsp;&nbsp;But, what about the stars that we see at night?&nbsp; I seem to recallthat the nearest star to Earth is about 2.5 million light years away.So, what if that star burned out a million years ago.&nbsp; We would still beseeing the light from this star for another 1.5 million years.&nbsp; And thatis just the closest one!&nbsp;&nbsp;&nbsp;So, is it theoretically possible that ALL of the starlight we see iscoming from stars that have in fact burned out, and are not even reallythere anymore, and that all we're seeing is the light that left thembefore they burned out?&nbsp;&nbsp;&nbsp;Any logical reply in words that I can comprehend, or a reference tosomewhere I can read about this would be much appreciated.&nbsp; Thanks! <br />Posted by stewartt</DIV><br />The most distant stars&nbsp;that we can see with telescopes&nbsp;are perhaps a billion light&nbsp;years away and were extremely bright a billion years ago. Since the brightest stars become black holes less than a billion years after their birth, likely all these stars are dark now, but the light will continue to arrive for many more years.</p><p>Farther away we see only quasars,&nbsp;super nova and large groups of stars = galaxies, most of which have likely dimmed over the billions of years, but galaxies&nbsp;are mostly&nbsp;dim stars which continue to give a little light for about a trillion years, so likely none of the galaxies we presently see are now completely dark if you were nearby.&nbsp;&nbsp; Neil&nbsp;</p>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The most distant stars&nbsp;that we can see with telescopes&nbsp;are perhaps a billion light&nbsp;years away and were extremely bright a billion years ago.<br /> Posted by neilsox</DIV></p><p>I could be wrong here, but I would guess that cepheid variables at couple hundred million light years distance are about the best we can do.&nbsp; This is assuming we're talking about stars in their main sequence as supernovae can been seen much further away.&nbsp; Just recently, there was a gamma ray burst that would have been visible to the naked eye from a distance of 6 or 7 billion light years away.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>