Can we tell when a Star has died the moment it happens?

In summary, light from the Andromeda Galaxy that we see now was created millions of years ago, when the genus Homo first appeared on Earth. It is possible for a star to die and disappear, but we would not know about it until the light from that event reaches us, which could take millions of years. This is because the time it takes for light to travel to us is the same as the distance in light years. Even the light from our own Sun is 8 minutes old by the time we see it on Earth.
  • #1
GKDAIR
7
0
Light just now reaching us from Andromeda Galaxy was created literally millions of years ago, around 2.5 to be in the ballpark.

When you look at a star, you're literally looking at the past.

That means tonight, when we look up, The light that let's us see Andromeda was created when the genus Homo first appeared here on Earth.


Is it possible that Andromenda, or any other star for that matter, could be dead and gone, but we don't know about it because the light hasn't traveled far enough yet?

Like for example, if Andromeda just suddenly died today, would we know about it? Or would we not find out until 2.5 million years from now and suddenly realize we can't see it anymore

Hopefully I'm phrasing my question correctly.
 
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  • #2
Yes we only see the light that was emitted 2.5 million years ago, if andromeda or anyother star went supernova today we won't know until enough time has past for that light to reach us. The time in years is the same as the number of light years away the object is. Even for our own Sun the light is 8 minutes old by the time we see it here on earth.
 
  • #3
Trollcast basically summed it up. Even when our Sun becomes a red giant, we will not be able to tell until about 8 minutes after the actual event. But at the point we find it out. We will all be killed so it really won't matter.
 
  • #4
Ah, that's what I figured. Thanks for clearing that up.
 
  • #5
ConnorL0404 said:
Trollcast basically summed it up. Even when our Sun becomes a red giant, we will not be able to tell until about 8 minutes after the actual event. But at the point we find it out. We will all be killed so it really won't matter.

Well... to be clear, becoming a red giant is a continual process that takes thousands to millions of years once it's started, not an event that just suddenly happens.

But yes, it takes 8 minutes for any changes in the sun to reach us.
 
  • #6
I remember reading a very short SciFi story about a mage who told his emperor he discovered how to make a star disappear. Emperor pointed to some star and asked the mage to do his trick. And the mage did, but the star was still twinkling...

If memory serves me well story didn't end up good for the mage. Emperor had some disappearing tricks ready too, and because of the much smaller distance their effects were visible instantly.
 

1. How do we know when a star has died?

We can tell when a star has died by observing changes in its brightness and spectral characteristics. When a star runs out of fuel, it can no longer sustain the nuclear reactions that keep it burning and it begins to cool down and dim. This change in brightness can be observed by telescopes and other instruments.

2. Can we tell when a star has died instantly?

No, we cannot tell when a star has died instantly. It takes time for the changes in brightness and spectral characteristics to be observed and confirmed by scientists. Depending on the distance of the star from Earth, it may take anywhere from a few years to millions of years for us to know that a star has died.

3. What happens when a star dies?

When a star dies, it can go through several different stages depending on its size. Smaller stars, like our sun, will become a white dwarf. Larger stars may become a neutron star or a black hole. During this process, the star will release a large amount of energy in the form of a supernova explosion.

4. Can we see a star die with the naked eye?

It is extremely rare for a star to die in a way that is visible to the naked eye. Supernova explosions, which occur when a large star dies, are one of the only ways we can see a star die with the naked eye. However, these events are very rare and can only be seen from Earth a few times every century.

5. How can studying a star's death help us understand the universe?

Studying a star's death can provide valuable insight into the life cycle of stars and the processes that govern the universe. By observing and understanding how stars die, we can better understand how they are born and how they contribute to the formation of galaxies. This knowledge can also help us make predictions about the future of our own sun and other stars in our galaxy.

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