Is it possible to say that many of the stars we see on the sky nowadays no longer exists?

Question

for example, the north stars, la osa mayor( in spanish) that we see everynight are still existing or they have already dissapear.

Answer 1

Bunch of idiots that are answering this question yes...they are either completely clueless about our galaxy or missed the inference that you are talking about stars visible to the naked eye.

Virtually all of "the stars we see" in our night sky are no more than 10,000 light years away. Since even a short-lived star will live several million years, and average stars live billions of years...it's quite unlikely that "many" of the stars we see in our night sky no longer exist. In fact, I would be willing to bet that almost none of them have passed into oblivion (including the North Star).

Of course, with telescopes we can see stars much farther away...millions of light years. And, yes, it is likely that many of those very distant stars no longer exist.

Answer 2

The short answer is "No", but given all the "Yes" answers read on before you judge too quickly.

Why do I choose "No." Because you asked about the stars we *see* at night when we look up. The vast majority of those stars are relatively near us, and most of them are main sequence, meaning that they are somewhere in the middle of their respective life spans. So, is it *possible* that Vega, which is estimated to be less than 4 x 10^8 years old at a distance of less than 8 pc, say, 25 light years, is no longer there? Possible, sure, but probable? No. It is only about half way through its expected life as a star. Even the biggest and brightest stars we see like Zeta Puppis, Lambda Orionis, Beta Orionis (Rigel), are generally thought to be young rather than old even though their life spans are shorter (Millions of years rather than billions of years). Sure, we see them at immense distances: >1000 pc, but they appear to shine steady (and bright!).

There are stars that do appear to be unstable, most for reasons that are not clear, like the Cepheid variables --the pole star you mentioned is a great example-- or the Mira variables and some of them do appear to be evolving quickly. Polaris (the pole star) may be have brightened by a full magnitude over the last 2 or 3 thousand years. Could Polaris have gone supernova in the past? Well, it certainly has the mass for it ( ~6 x sun), and if it did we won't know about because at 400 ly it could be as long as 400 years before we could know.

But this is just one star out of the 2000 thousand naked-eye stars, and as I pointed most of these are stable main sequence stars. So, most of them are still there.

If you move the question, however, to stars we can see with the largest and best telescopes, then the answer is most assuredly "Yes." Indeed, whole galaxies might no longer exist in the way we see them, their stars long since having settled down to white dwarfs, brown dwarfs and the like, with all free gas and dust long since used up to make new stars.

HTH

Charles

Answer 3

Not only possible but probable. The further away from Earth the star is, the longer it takes for the light to reach us. some stars that we currently see at night are so far away that the light left the stars in question millions of years ago.

Some stars, as a result, are still visible even though they may have exploded (gone supernovae) by now, it's just a matter of time before we see the beautiful effects in the sky.

Answer 4

It's *possible* but not likely.
It's possible because looking into space is sort of like a time machine -- it takes light many years to reach us from various stars. If, for example, Alpha Centauri were to go nova today, we wouldn't know about it for a little over 4 years (and that's one of the closest stars to us).
It's not likely because we know what *type* of stars most of the ones that are visible to us at night are, and we have a pretty good idea of where they are in their life cycle. The ones that are near the end of their lives (that will either turn into red giants or go supernova) are watched very carefully and very frequently -- because seeing them change states teaches us more about stars. There aren't very many in that situation -- the vast majority of stars you see at night are safely in the part of their lives where they'll be shining for many millions to billions of years to come.

One exception you might keep an eye on -- beta scorpii (scorpius rises about 3:30 AM in the south-east right now, beta is the middle star of the three lined up in the scorpion's "head"). It's been brightening erratically the last few years, and may be on its way to going nova -- astronomers are watching it very closely!

Answer 5

attainable, yet no longer life like. With only your eyes, you'll discover about 2000 stars on a good sparkling nighttime, and practically all of them are interior 4000 mild years. it is an noticeably very small time for a action picture star that lasts for billions of years. it must be form of like worrying about your chum because you have not seen her for 3 hours. maximum stars under no circumstances blowup, although those which will provide signs and indicators for most many 1000's of years in boost. There are only 2 or 3 stars interior 4000 mild years like that, or maybe those seem a minimum of one hundred,000 years remote from going supernova. Betelgeuse, to illustrate.

Answer 6

Depends on your definition of "many". I'd say no, almost all the stars we see are still there.

The life span of a star is measured in billions of years. We can only see (without a telescope) about 7,000. The odds that any one of them has gone nova, and we haven't gotten the news yet because the light from the nova is still travelling to us, is very small.

If you consider all the stars in the galaxy, the number of them that have gone nova in the last 100,000 years (the galaxy is about 100,000 light years across) is relatively small. I'd say maybe only about of one hundred thousandth of the stars that we can observe right now have actually gone boom already.

Answer 7

If you mean stars we can see with the naked eye, then no. They're all near neighbours in astronomical terms, even the most distant is "only" 1600 light years away, so we're seeing it as it was 1600 years ago. Stars do die, but they take much longer than a few thousand years building up to it - all the naked eye stars are in good health.

Answer 8

it's more than possible. I can gaurantee it almost. although the stars that are easy to see to the naked eye are far away, the chances of this phenomenon happening with one of them is small. but the stars that we can see using a telescope that are very far away, millions of light years away, are probably gone already. just think, the star has been shining light towards us for billions of years. then, they die and become a dwarf or giant or supernova or black hole. it would then take a million years for the light from the old star to stop shining on us. picture peeing off the empire state building. when you zip up and look down, the ground and hopefully the people, are still getting your treat from above.

Answer 9

Most likely all of them are still burning brightly. First, consider the statistics. You can see maybe a total of 5,000 stars. Assuming an average life span of one billion years, you can expect to lose one star every 200,000 years. Secondly, stars don't just suddenly blow up or go out - they go through a long (to us) period of instability as they use up the last of their fuel. Small stars lose their outer layer of hydrogen and form planetary nebulae (http://www.spitzer.caltech.edu/Media/releases/ssc2004-13/release.shtml ), very large stars undergo more dramatic death throes and explode as supernova. There is one star in the southern hemisphere, Eta Carinae, that appears to be close to going: http://en.wikipedia.org/wiki/Eta_Carinae

Answer 10

Sure, it's quite possible. What we see today is the light that was emitted by a star as long ago as the light took to reach the earth. Any particular star may well have exploded or died by now, and we would never know it for a long time.