Stargazing How can we see the ISS at 200 miles away with the naked eye?

[russ_watters]

what about pictures of the full moon and stars?

Generally they are composites. You can't easily do both with one shot.

 

[DaveC426913]

Generally they are composites. You can't do both with one shot.

To be pedantic, you can. The OP did not seem to be too concerned about the aesthetics of the result (i.e. a blown out Moon is still serviceably visible for his purposes).

 

[malawi_glenn]

Is Gaia an empirical source of observation?

The OP wanted to trust direct observation (presumably as opposed to derivation based on various theories that are still being tweaked.)

It measures parallax and motion of stars.

If you just want to use your senses, you can not do parallax accurately up to 300 lightyears.

 

[russ_watters]

To be pedantic, you can. The OP did not seem to be too concerned about the aesthetics of the result (i.e. a blown out Moon is still quite visible).

Sigh, fine. I added a qualifier.

 

[TruthSeeker777]

What makes you think we can't verify their distances empirically?

The parallax method can tell us the distances to nearby stars with nothing more than the geometry of Earth's orbit and six months of waiting time.

It depends on what relative distances you set for the objects around what you are trying to triangulate? It assumes you know the distance to an object X and you measure the angular drift in reference to that object Y compared to the other you know about X ? So what is the reference object ?

 

[DaveC426913]

If you just want to use your senses, you can not do parallax accurately up to 300 lightyears.

Sure, that's not the point.

The OP wants to rely on empirical evidence. By that I presume he means "don't rely on our theories of stellar distance calculation".

Telescopes provide the requested empirical observation. We see the parallax.

 

[malawi_glenn]

By that I presume he means "don't rely on our theories of stellar distance calculation".

Google is your friend here.

Two of my teachers in astrophysics were (are) involved in the Gaia-project.

 

[malawi_glenn]

It depends on what relative distances you set for the objects around what you are trying to triangulate? It assumes you know the distance to an object X and you measure the angular drift in reference to that object Y compared to the other you know about X ? So what is the reference object ?

You want a crash course in parallax method?

 

[DaveC426913]

Google is your friend here.

Two of my teachers in astrophysics were (are) involved in the Gaia-project.

So what? The OP doesn't want to rely on astrophysical theory. We can accommodate that by simply using telescope observation. What is there to Google? (That is a rhetorical question.)

 

[malawi_glenn]

So what?

If you want to know how Gaia works, you can google it.

 

[DaveC426913]

It depends on what relative distances you set for the objects around what you are trying to triangulate? It assumes you know the distance to an object X and you measure the angular drift in reference to that object Y compared to the other you know about X ? So what is the reference object ?

It is straight up geometry.
We know Earth's orbital diameter.
We can treat the background of stars as residing at infinity. We don't have to know how far away any given reference star is - we only need to know that, collectively, they are effectively at infinity. (This can be elaborated on, if need be.)

 

[DaveC426913]

If you want to know how Gaia works, you can google it.

Please see post 50.

 

[malawi_glenn]

Please see post 50.

Ah cool, I did not see that!

 

[TruthSeeker777]

It is straight up geometry.
We know Earth's orbital diameter.
We can treat the background of stars as residing at infinity. We don't have to know how far away any given reference star is - we only need to know that, collectively, they are effectively at infinity. (This can be elaborated on, if need be.)

What if we remove that infinity assumption of stars distance? What is that based upon?

 

[TruthSeeker777]

What if we remove that infinity assumption of stars distance? What is that based upon?

Where is the evidence the sun is a star?

 

[malawi_glenn]

What if we remove that infinity assumption of stars distance? What is that based upon?

That is where a source of error in the method lies.
But you can figure out which stars are static for all pratical purposes
https://cdn.mos.cms.futurecdn.net/HXuWest5ghEazEfJKpjQKV-1200-80.gif
That "movie" took some years to produce. Look how some stars travels a lot, both due to parallax and due to intrinsic motion. Whearas some are static given in this resolution.

 

[DaveC426913]

Where is the evidence the sun is a star?

What?

Methinks them's trollin' words.

 

[Baluncore]

Where is the evidence the sun is a star?

Where is the evidence that the stars are like our sun?

 

[malawi_glenn]

Where is the evidence that the stars are like our sun?

Where is the evidence that the sun exists?!

 

[Baluncore]

Where is the evidence that the sun exists?!

Would I need to exist to answer that question?

 

[malawi_glenn]

Where is the evidence the sun is a star?

Huge neutrino flux. Hence, fusion is occurring.
You did ask "where" and not "what". So you want a GPS coordinate or something?
But feel happy to travel to the sun (if it exists) and measure with your own senses

 

[DaveC426913]

Where is the evidence the sun is a star?

The straight up answer is that this is a physics forum that encourages and supports established mainstream science. If you are looking to challenge mainstream science, you are free to do so - but this is not the place.

 

[TruthSeeker777]

The straight up answer is that this is a physics forum that encourages and supports established mainstream science. If you are looking to challenge mainstream science, you are free to do so - but this is not the place.

There are a lot of assumptions in the answers which we can't verify empirically.. Why do we assume the sun is a star? Why do we assume the stars at at an infinite distance? Can we verify this?

 

[Ibix]

Why do we assume the stars at at an infinite distance?

We don't.

 

[DaveC426913]

There are a lot of assumptions in the answers which we can't verify empirically.. Why do we assume the sun is a star?

We do not assume these things. They are part of an established astrophysical model, that has been built up over centuries, and they work extremely well.

You should read the forum rules before proceeding along this line, because it's pretty explicit about "established mainstream science".

Why do we assume the stars at at an infinite distance? Can we verify this?

Not that they "are" - but that they can be "treated as such" for the purpose of the geometry.

A nearly unlimited list of stars and galaxies and other objects are candidates for reference because they all have effectively zero relative movement. Every star we add to a collective reference frame further cements the justification for treating it as too far way to affect the parallax measurement of a nearby star.

Imagine I hold up my thumb and try to measure the parallax of my two eyes against some distant mountain peaks. The mountains are not at infinity, but their actual distance is immaterial to my parallax measurement.

And, if I measure hundred peaks, or a hundred thousand, I see that they all have zero relative movement between them, then I can indeed, treat the collection of mountain peaks as if it is at infinity for the purpose of the parallax geometry (which is simply the same as saying the lines of sight (from mountain collective to each eye) are parallel to within acceptable tolerance for my measurement of the parallax).And that may be an easier easy of seeing it. The lines of sight (from very distant stars to Earth's winter and summer positions) are parallel to within a very small margin of error. Againt these parallel lines of sight, we can accurately determine with simple geometry how far away nearby stars are.

 

[malawi_glenn]

There are a lot of assumptions in the answers which we can't verify empirically.. Why do we assume the sun is a star? Why do we assume the stars at at an infinite distance? Can we verify this?

- We define the sun to be a star due to the observational knowledge we have about it. The Sun defines what it means for something be star, it is the role model if you will.
We do not assume that the sun is a star, thousands of people smarter than you and me have studied the sun in thousands of ways over a couple of centuries.

- Did you look at the gif-video showing that night star over the course of 3 years (or whatever the time frame was)?
Background stars are not assumed to be infinite far away, they do have parallalax movement on the sky. BUT that motion is so tiny that we can not detectet it, thus for calculational purposes we can treat their distance from us as "infinite". They can not be literary infinite away from us, you know that, otherwise we would not see their light.

We can not "see" atoms, or semicondutors etc and so on with our eyes. Still you use them to write here on this forum. And you trust that the scientists and engineers know how those things work and can "tame" them to make your precious little computer or smart phone. Why do you trust them?

Physics is an observational and experimental driven field of natural science where mathmatical models are used to organize, structure, generelize our findings. Using these models, we can make predictions for what we would measure and observe in something we have not tried yet. Thus, a physical model is falsifiable. Sometimes we measure something exactly as it was predicted (within experiemental margin of error), sometimes we measure something which was not exactly as it was predicted, but still not too far away to make the model disposable. And sometimes, we measure things that was not predicted, and thus model is discarded.

Physics is not about The Truth^TM, it is about finding structure in what we see and measure using mathematical models. If you seek the truth, physics is not for you.

 

[TruthSeeker777]

I just find anything in common between the stars and the sun. What is the core of the assumption that the sun is a star? Is there a paper for this?

 

[malawi_glenn]

I just find anything in common between the stars and the sun. What is the core of the assumption that the sun is a star? Is there a paper for this?

There is no assumption in that the sun is star... read my post above.

Are you perhaps meaning those other luminous objects that we observe in the night-sky, why we know that those objects have very similar properties as the sun? I.e. gigantic spheroids of plasma held together by gravity in which fusion takes place in their core?

 

[DaveC426913]

I just find anything in common between the stars and the sun. What is the core of the assumption that the sun is a star? Is there a paper for this?

Please: new topic; new thread.

That is the PF way.

 

[hutchphd]

I just find anything in common between the stars and the sun. What is the core of the assumption that the sun is a star? Is there a paper for this?

The stars are in fact holes in the celestial sphere and the sun is of course different, being a god driven in a golden chariot.
This is not entertaining.

 

[russ_watters]

The stars are in fact holes in the celestial sphere and the sun is of course different, being a god driven in a golden chariot.
This is not entertaining.

I just find anything in common between the stars and the sun. What is the core of the assumption that the sun is a star? Is there a paper for this?

It seems you believe that much about our current understanding of the universe is wrong, but at the same time you know practically nothing about our current understanding of the universe. These two issues are clearly related. We can help with the second, but only if you drop the first and make an honest effort at learning. But we won't entertain the posture you've taken. No, this schtick is not entertaining. Thread locked.