Jinxter13 Posted December 20, 2015 Share Posted December 20, 2015 (edited) With the naked eye at night we see a lot of stars, I'm told by the folks on the 'net that the light we see left those starts somewhere in the neighborhood of a million years ago , Ok now with the question(s) if that's so and one of those stars went nova and exploded into nothing but fragments; how long would it take before we realized it was gone, or before the light disappeared?. If a star became a dwarf how long would it be before the light went out?. It is said that some stars I think Betelgeuse being one is thousands of times larger than our sun, if so how long/large or the solar flares it emits. *Our sun is tiny compared to the really big stars out there! Eta Carinae, over five million times larger than our sun. Betelgeuse, three hundred times larger than Eta Carinae*. :blink: , I was told Betelgeuse was large...but OH WOW!!!!. I'm hoping some of ARC's more cerebral Astronomy buffs will pipe up/sound off/chime in. Edited December 20, 2015 by #1 Greywolf Quote Link to post Share on other sites
vince14 Posted December 20, 2015 Share Posted December 20, 2015 Depends how far away the star is, because light, well, travels at the speed of light. So if a star was 300 light years away and 'exploded' today, we wouldn't see that on Earth until the year 2315. If the star was 50 light years away, we'd observe it in the year 2065. If you're interested in how big or small various objects within the universe are, the check out The Scale of the Universe website. Quote Link to post Share on other sites
midnightprowler Posted December 20, 2015 Share Posted December 20, 2015 Light travels at 186,000 miles per second. The moon is about 1.5 light seconds away, the sun, 8 light minutes. The nearest star, other than the sun, Alpha Centuri, is a little over 4 light years away. All the stars you see are at different distances. Quote Link to post Share on other sites
kenlilly106 Posted December 20, 2015 Share Posted December 20, 2015 Under ideal conditions (no light pollution, clear sky) with normal unassisted vision you can see stars out to around 1,600 light years, that equates to just under 10,000 visible stars for both hemispheres. Link Here's a good picture that shows the scale of the Milky Way, the yellow circle is the 1,600 light year limit. (big image) pic Supernova are are a more complicated case because one is brighter than its parent star by a large margin, so a start that was not naked eye visible can produce a supernova that will be. When Betelgeuse goes supernova it's expected to be brighter than the full moon and visible in daylight. A stellar remant cooling from a white dwarf to a black dwarf is estimated to take 1015 years or so. Ken (astronomy buff) Quote Link to post Share on other sites
K2Pete Posted December 20, 2015 Share Posted December 20, 2015 With the naked eye at night we see a lot of stars, I'm told by the folks on the 'net that the light we see left those starts somewhere in the neighborhood of a million years ago :hmmm:/>, Ok now with the question(s) if that's so and one of those stars went nova and exploded into nothing but fragments; how long would it take before we realized it was gone, or before the light disappeared?. Seeing as you're from Andromeda Galaxy, how long did it take for us to see your message? Kidding aside ... you answered your own question already. When these stars blow up, it'll take millions or thousands of years for us to see it, depending on just how far they are from us. IIRC back in the 1060's a Nova was seen, and documented by the Chinese, it could be seen during the day and lasted for just months, then it went dim. Simple as that! ... unless I misunderstood ... Pete Quote Link to post Share on other sites
Flankerman Posted December 20, 2015 Share Posted December 20, 2015 (edited) FWIW........ Arthur C Clarke wrote a moving short story about a supernova that destroyed a very advanced civilisation. Space scientists observing the remains proved it to be the same star that shone as the Star of Bethlehem on Earth.... From Wiki..... The final paragraph of "The Star" reveals the source of the priest's pain. Determining the exact year of the long-ago supernova and the star system's distance from Earth, he calculated the date the emitted light from the explosion reached Earth, proving that the cataclysm that destroyed the peaceful planet was the same star that heralded the birth of Jesus. The scientist's faith is shaken because of the apparent capriciousness of God: The final sentence reads..... Oh God, there were so many stars you could have used. What was the need to give these people to the fire, that the symbol of their passing might shine above Bethlehem? I'm not in the least bit religious - but the story made a lasting impression on me as I read it as a teenager over half a century ago... Ken Edited December 20, 2015 by Flankerman Quote Link to post Share on other sites
fulcrum1 Posted December 20, 2015 Share Posted December 20, 2015 (edited) Ok now with the question(s) if that's so and one of those stars went nova and exploded into nothing but fragments; how long would it take before we realized it was gone, or before the light disappeared?. If a star became a dwarf how long would it be before the light went out?. It is said that some stars I think Betelgeuse being one is thousands of times larger than our sun, if so how long/large or the solar flares it emits. You mean supernova? There is a difference and differences within those two categories. Generally speaking how you find one is the star increases in luminosity and a stargazer or computer sees it and reports it. Then the nerds grab the telescope and head for a dark site to watch over several weeks until you cannot see it anymore. For a more technical description Wikipedia does a fantastic job with this along with showing tables for stars within our Galaxy ready to blow (probably won't happen in our lifetime) and describes the differences with Dwarf stars. No one knows how long a white dwarf will still emit light, the coolest white dwarfs that are still pumping out Kelvins will continue doing so long after we're gone. However old the Universe is isn't enough time for a white to go black. Edited December 20, 2015 by fulcrum1 Quote Link to post Share on other sites
toadwbg Posted December 20, 2015 Share Posted December 20, 2015 Betelgeuse! Betelgeuse! Beteljuice! I had to be the first to do that... Quote Link to post Share on other sites
Scott R Wilson Posted December 21, 2015 Share Posted December 21, 2015 You might want to check out Dr. Phil Plait's "Crash Course Astronomy" videos if astronomy interests you. Here's one on super massive stars and what happens to them: Quote Link to post Share on other sites
Trigger Posted December 21, 2015 Share Posted December 21, 2015 Depends how far away the star is, because light, well, travels at the speed of light. So if a star was 300 light years away and 'exploded' today, we wouldn't see that on Earth until the year 2315. If the star was 50 light years away, we'd observe it in the year 2065. Right. And to that point, if one looks up into the night sky at a particular supernova (or galaxy or nebula or star), and because of the vast distances, we aren't seeing how that object appears now, but what it looked like some time ago (when the light was emitted, however long ago that was). You are - in effect - looking back in time. Some of those objects don't even exist any more, and yet their light is still traveling across the universe. Quote Link to post Share on other sites
Flankerman Posted December 21, 2015 Share Posted December 21, 2015 Even closer to home - when you watch a sunset, you are watching something that happened 8 minutes ago !! Ken Quote Link to post Share on other sites
TomcatFanatic123 Posted December 21, 2015 Share Posted December 21, 2015 I really don't have anything to add to this knowledge wise, but I just have to say, isn't the scale of everything in the universe absolutely awe-inspiring? Just hearing stuff like, 'oh, this star is so young, it's only 500 million years old,' or 'yeah, that galaxy is right next door, it's just 2000 light years away.' I think it's simply fascinating. Quote Link to post Share on other sites
Trigger Posted December 21, 2015 Share Posted December 21, 2015 Quote Link to post Share on other sites
vince14 Posted December 21, 2015 Share Posted December 21, 2015 What if I were to tell you that the Sun is still visible after it is geometrically below the horizon... Quote Link to post Share on other sites
Flankerman Posted December 21, 2015 Share Posted December 21, 2015 What if I were to tell you that the Sun is still visible after it is geometrically below the horizon... I think the sun is visible at all times - depending where you are viewing it from........ Sorry.... I'll get my coat. Ken Quote Link to post Share on other sites
Jinxter13 Posted December 21, 2015 Author Share Posted December 21, 2015 ?????....what am I missing here? Quote Link to post Share on other sites
Scott R Wilson Posted December 21, 2015 Share Posted December 21, 2015 Another couple of videos illustrating size comparisons: Quote Link to post Share on other sites
Trigger Posted December 21, 2015 Share Posted December 21, 2015 What if I were to tell you that the Sun is still visible after it is geometrically below the horizon... IKR! I believe that that's what Flankerman was referring to. Stuff like that, the distances involved... MindBlown.gif Quote Link to post Share on other sites
jpk Posted December 26, 2015 Share Posted December 26, 2015 I watched a short video that demonstrated the relative size of the solar system. It was based in the earth being the size of a marble. Besides distance, they used different sized spheres to show the scale of sizes of the other objects in the solar system relative to the marble sized earth. The sun was around 1.5 meters in diameter. The orbit of Neptune was over seven miles away from the sun. The objective of the video was to show the relative distances are and how vast even our small solar system is. Quote Link to post Share on other sites
rightwinger26 Posted December 26, 2015 Share Posted December 26, 2015 (edited) The size and scope of the universe is absolutely amazing. One of my favorite pass times is to sit in the back yard with the telescope and watch. One of my favorite things is to watch Jupiter, if you watch it for long enough, you can "see" the cloud bands move, it's truly amazing to see something that far away with your own eyes, and feel like it's right in front of you. Now is a very good time to watch the Pleiades, or Saturn if you have the means. Bill Edited December 26, 2015 by rightwinger26 Quote Link to post Share on other sites
Scott R Wilson Posted December 26, 2015 Share Posted December 26, 2015 I watched a short video that demonstrated the relative size of the solar system. It was based in the earth being the size of a marble. Besides distance, they used different sized spheres to show the scale of sizes of the other objects in the solar system relative to the marble sized earth. The sun was around 1.5 meters in diameter. The orbit of Neptune was over seven miles away from the sun. The objective of the video was to show the relative distances are and how vast even our small solar system is. This one? Quote Link to post Share on other sites
Scott R Wilson Posted December 26, 2015 Share Posted December 26, 2015 This video does an excellent job comparing sizes from the very small to the very large: Quote Link to post Share on other sites
habu2 Posted December 27, 2015 Share Posted December 27, 2015 For Christmas I received a book about the Hubble telescope. Captions with the Hubble images stated the distance in light years to each image. When you think about galaxies over two billion light years away, and the vast distances that involves, well it just boggles my mind. I can't wrap my brain around something that immense. Then the book explained how Hubble helped prove the universe is still expanding....... Quote Link to post Share on other sites
Jinxter13 Posted December 27, 2015 Author Share Posted December 27, 2015 .......When you think about galaxies over two billion light years away, and the vast distances that involves, well it just boggles my mind. I can't wrap my brain around something that immense. Then the book explained how Hubble helped prove the universe is still expanding....... I imagine if a crew on a starship similar to Star Treks Enterprise NCC 1701D....went on a voyage to a distant galaxy and the ship returned to its point of origin....the crew that returned with the craft; would return to a planet/world as alien to them as any they had encountered during the voyage. I can't put a number on how many generations would have been born and passed during such a journey. A lot of food for thought and data has been presented in the thread a Big ARC thanx to all who replied. Quote Link to post Share on other sites
kenlilly106 Posted December 28, 2015 Share Posted December 28, 2015 Here's something for perspective on the distances involved, 45 minutes at light speed starting at the center of the sun. Vimeo link Quote Link to post Share on other sites
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