We can see a bunch of stars in the night sky, and there are many types. Sometimes we see a star turn from one type to another. Differently sized stars follow different paths. We never see the full path of a star because that takes forever, but we’ve seen enough stars transform once to have a good idea. We also come up with physics based explanations for why each of these transformations happen and in each category of stars.
We know what type of star our sun is and we can use physics to predict what type of transformation is next and when it will likely happen
They can tell, using spectroscopy, what the Sun is made of, and in what proportions. They can calculate, using measurements of gravity and physical observable size, how those proportions scale to specific amounts of hydrogen, helium, etc. Then they can figure out how big and how hot the volume is where fusion is taking place and therefore how fast it is occurring and how fast it’s going to use up its fuel and start the end throes of its life cycle.
A few different ways; we actually have very good images of stars of varying size in various phases of their life that are from distant parts of the universe. So we can tell that based on our suns size and phase in life about how much time is left. It might be off a few hundred million years but that’s a rounding error in the stars life. Secondly based on models we know how long nuclear fusion reactions last. Given the suns size and mass we can approximate how much fuel is there and how quickly it will run out.
We notice the growth of many examples of that species and categorize different phases.
Then, when we see a new member of this species we can try to figure out it’s growth phase, and from that we can estimate it’s remaining life.
We do very similar with the sun – given it’s size, it’s distribution of material (what % of it is hydrogen) we can estimate what part of it’s life cycle it is on (and how much fuel it has left) and from that we can know it’s lifespan
We have a pretty good understanding of the lifespans of stars and stellar evolution for our observations of all the stars out there, and we also have a good understanding of the nuclear processes that happen inside stars.
Based on that, we see that stars similar to our sun spend about 10 billion years in the main sequence, which is the phase of stellar evolution that our sun is currently in. We also know that our sun is around 4.6 billion years old, meaning it has somewhere in the neighborhood of 5 billion years left in the main sequence. Then it will transition into a red giant, which it will be for another 1 billion years or so. After that, it will become a white dwarf, which it will be for many trillions of years.
So our sun isn’t going to die in 5 billion years, but it will transition out of being a main sequence star into a red giant around that time, and when it does, it will probably engulf the Earth, or at least render it totally uninhabitable.
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Literally just chatgpt it or better yet type it into google and see the gemini response smh
We can see a bunch of stars in the night sky, and there are many types. Sometimes we see a star turn from one type to another. Differently sized stars follow different paths. We never see the full path of a star because that takes forever, but we’ve seen enough stars transform once to have a good idea. We also come up with physics based explanations for why each of these transformations happen and in each category of stars.
We know what type of star our sun is and we can use physics to predict what type of transformation is next and when it will likely happen
(Im using we to refer to us humans collectively)
They can tell, using spectroscopy, what the Sun is made of, and in what proportions. They can calculate, using measurements of gravity and physical observable size, how those proportions scale to specific amounts of hydrogen, helium, etc. Then they can figure out how big and how hot the volume is where fusion is taking place and therefore how fast it is occurring and how fast it’s going to use up its fuel and start the end throes of its life cycle.
A few different ways; we actually have very good images of stars of varying size in various phases of their life that are from distant parts of the universe. So we can tell that based on our suns size and phase in life about how much time is left. It might be off a few hundred million years but that’s a rounding error in the stars life. Secondly based on models we know how long nuclear fusion reactions last. Given the suns size and mass we can approximate how much fuel is there and how quickly it will run out.
How do we know how long pets live?
We notice the growth of many examples of that species and categorize different phases.
Then, when we see a new member of this species we can try to figure out it’s growth phase, and from that we can estimate it’s remaining life.
We do very similar with the sun – given it’s size, it’s distribution of material (what % of it is hydrogen) we can estimate what part of it’s life cycle it is on (and how much fuel it has left) and from that we can know it’s lifespan
We have a pretty good understanding of the lifespans of stars and stellar evolution for our observations of all the stars out there, and we also have a good understanding of the nuclear processes that happen inside stars.
Based on that, we see that stars similar to our sun spend about 10 billion years in the main sequence, which is the phase of stellar evolution that our sun is currently in. We also know that our sun is around 4.6 billion years old, meaning it has somewhere in the neighborhood of 5 billion years left in the main sequence. Then it will transition into a red giant, which it will be for another 1 billion years or so. After that, it will become a white dwarf, which it will be for many trillions of years.
So our sun isn’t going to die in 5 billion years, but it will transition out of being a main sequence star into a red giant around that time, and when it does, it will probably engulf the Earth, or at least render it totally uninhabitable.