Are Deep Space Objects Still There?

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In summary: Individual stars in neighboring galaxies can be seen by telescope. The Cepheid variables give the information needed for distance. In distant galaxies, type Ia supernovae are visible - their observation led to the observation that expansion of the universe is speeding up.Individual stars in neighboring galaxies can be seen by telescope. The Cepheid variables give the information needed for distance. In distant galaxies, type Ia supernovae are visible - their observation led to the observation that expansion of the universe is speeding up.
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The light by which we see distant deep space objects left those objects thousands, millions, even billions of years ago, yet we speak of them in the present tense, Perhaps this is just a convenience; they may be more accurately referred to in the past tense. In any event, given that the light forming the images we see actually left the objects so long ago, how do we know they still exist?
 
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basically all stars we can resolve individually are located in our own galaxy, so none of them is further than approximately 150 000 light years, so for those farest away we see them as they appeared 150 000 years ago. This is quite short period comparing to lifecycle of most of stars, so almost all of them still exist in the same stage as we see them, but a small part might have evolved meanwhile to another stages of their life, including stellar remnants. But we have models of stellar evolution so we can predict their current stage.
 
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For the objects further away, we talk about galaxies. They would still exist, evolved however (depending on their observed distance), some of them merged. Anyway we have models for that as well, so we can predict that.
 
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btw I think astronomers are probably not so interested in the "current" status of the farest objects. Any information originated at those object cannot travel faster than light, including any gravitational influence, they might have on us. If astronomers want know how the galaxies in the universe looks right now, they just observe our close neighborhood.
 
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Individual stars in neighboring galaxies can be seen by telescope. The Cepheid variables give the information needed for distance. In distant galaxies, type Ia supernovae are visible - their observation led to the observation that expansion of the universe is speeding up.
 
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mathman said:
Individual stars in neighboring galaxies can be seen by telescope. The Cepheid variables give the information needed for distance. In distant galaxies, type Ia supernovae are visible - their observation led to the observation that expansion of the universe is speeding up.

Correct, I should have added "by naked eye" in my first post to be clear. I assumed (perhaps incorrectly) that OP's thoughts emerged when looking at the night sky with all its beauty and majesty, as usually is my case :)
 
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lomidrevo said:
If astronomers want know how the galaxies in the universe looks right now, they just observe our close neighborhood.

I sometimes fall into the trap of forgetting that objects at the edge of the observable universe, per the hypothetical co-moving clock, are not actually older than objects right next door. A comment like the one you made is a great anchor for my intuition.
 
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1. What are deep space objects?

Deep space objects refer to any astronomical object located outside of our solar system. These can include galaxies, nebulae, star clusters, and other celestial bodies.

2. How do we know if deep space objects are still there?

Scientists use powerful telescopes and other instruments to observe and track deep space objects. By monitoring their movements and changes in brightness, we can determine if they are still present in their expected locations.

3. Can deep space objects disappear?

While it is rare for deep space objects to completely disappear, they can appear to disappear from our perspective due to a phenomenon known as occultation. This occurs when a foreground object blocks our view of the deep space object, making it appear to disappear.

4. What factors can affect the visibility of deep space objects?

The visibility of deep space objects can be affected by various factors, such as atmospheric conditions, light pollution, and the location of the object in the sky. Additionally, the distance and size of the object can also impact its visibility.

5. How far away are deep space objects?

Deep space objects can vary greatly in their distance from Earth. Some may be relatively close, within our own Milky Way galaxy, while others can be billions of light-years away in other galaxies. The farthest known deep space object is GN-z11, which is approximately 13.4 billion light-years away.

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