How Do Astronomers Compose These Pictures?

[eohrnberger]

I've been enjoying some astronomy programs for awhile now, and I suddenly struck me.

How Do Astronomers Compose These Pictures?

How do we know what the location of all those stars are relative to the Earth?
How do we know where to put them all?

 

[spud_meister]

Artistic license .

 

[Xelor]

I've been enjoying some astronomy programs for awhile now, and I suddenly struck me.

How Do Astronomers Compose These Pictures?

How do we know what the location of all those stars are relative to the Earth?
How do we know where to put them all?

How do we know what the location of all those stars are relative to the Earth?

Did you bother to Google for an answer?

​

Don't get me wrong. I'm thrilled you've thought to ask the question; that's the fundamental behavior one must exhibit to develop knowledge. I'm just astounded that you asked it here.

 

[Grim17]

I've been enjoying some astronomy programs for awhile now, and I suddenly struck me.

How Do Astronomers Compose These Pictures?

How do we know what the location of all those stars are relative to the Earth?
How do we know where to put them all?

Everything is a guess. Since it's impossible to see what's on the other side of our galaxy, astronomers really have no idea what it actually looks like, so they create a rendering based on other spiral galaxies. They are reasonably sure our solar system is located between 2 spiral arms, that the Milky Way is a bar type spiral galaxy and that we are around 25,000 light years from the galaxy's center.

.

 

[Xelor]

Artistic license .

 

[eohrnberger]

How do we know what the location of all those stars are relative to the Earth?

Did you bother to Google for an answer?

​

Don't get me wrong. I'm thrilled you've thought to ask the question; that's the fundamental behavior one must exhibit to develop knowledge. I'm just astounded that you asked it here.

I'm sitting here watching the show and perusing threads here, watching the show on Galaxies, and it just struck me and I asked, so rather impulsive than thoughtful, I guess. :shrug:

 

[eohrnberger]

No, I don't think artistic license.

Now, I haven't watched the video posted, so I'm no more informed than I was before, so my guess, at this moment, is that there's a lot, like a really lot of math involved.

Sitting here on the Earth, that's rotating giving us the days,
orbiting the sun that gives us years,
the sun is orbiting the galactic center,
(and probably a couple of more layers of orbits)

Observations as to where that point of light that outside our galaxy is going to be on a night by night basis would have to all this into account.

The same would have to be said for all the points of light that are stars inside of the Milky Way.

Given a fair number of observations of a specific star, specifics as to red shift (distance), elevation, location, time of observation, etc. etc. then I suppose its possible make a calculated position for this one star, and if it can be done for one star it can be done for a great many stars, it'll just take longer.

Now. On to watch the posted video, see if my guess is right.

 

[Xelor]

I'm sitting here watching the show and perusing threads here, watching the show on Galaxies, and it just struck me and I asked, so rather impulsive than thoughtful, I guess. :shrug:

Understood.

I presume you now know the answers to your questions, that is I know you should know them if read the linked article and watched two videos.

 

[eohrnberger]

Understood.

I presume you now know the answers to your questions, that is I know you should know them if read the linked article and watched two videos.

Yeah, kinda guessed correctly, I think. Lots and lots of data, and lots and lots of math, applied to the data. The data visualizations presented are all data driven renderings.

 

[Xelor]

Yeah, kinda guessed correctly, I think. Lots and lots of data, and lots and lots of math, applied to the data. The data visualizations presented are all data driven renderings.

That's a fair "rough and dirty" summation of how astrophysicists develop the images about which you asked.

And as you noted above, the imagery is most certainly not the result of merely guessing.

Lastly, yes, you "guessed" correctly. More importantly, your process of...

1. Receiving stimuli.
2. Thinking about the stimuli and its potential implications regarding "something."
3. Asking a neutrally phrased and objectively answerable question(s) about the relationship between the stimuli and the "something." (Normally, one asks oneself and tries to find the answer for oneself before asking others.)
4. Guessing at what may be the nature, extent and timing of that relationship. (abducting/abductive reasoning)
5. Seeking sound/cogent and credible information to actually answer the question and to prove/disprove the validity of the guess.
6. Sharing what your research revealed.

...is exactly the process every researcher (social and natural sciences, humanities and applied arts and sciences) used to figure out everything humanity has thus far figured out. Some folks call it "problem solving;" others call it the "scientific method." Whatever one calls it, learning how to do it, and doing it well and consistently, is:

• what school is all about,
• how one gets to be a leader in some field (academia, public service, business, etc.), and
• what one must do well to earn a master's degree or PhD, or the experiential rough equivalent of it, such as, say Bill Gates or other highly successful (as measured by their track record of goal achievement, not by the quantity of money they've earned) have obtained. (Note: the only thing distinguishing PhDs from "everyone else" is that the specific research questions they ask and answer haven't ever before been asked and answered. To laymen, it may not seem so; however, at the level of detail at which PhDs play, it becomes clear that's so.)

The process is applicable to just about any question one might ask.

So props to you for exhibiting that process here.

I don't see much DP discussion whereof there's any evidence that people actually fully avail their discourse of the problem solving process. Most of what I see evidence of is steps one through four, whereupon whatever folks have abducted, they present their guess as though it's "step six" information/conclusions that resulted from their having performed step five. Curiously, they do that despite how easy -- given the (1) immense quantity of "stuff" that's already been asked and answered, and (2) the power of Google and Google Scholar -- it is to perform step five. As you observed, if you clicked on the first hyperlink I provided in post 3 and watched the two videos, for the vast majority of questions folks will here have, one need only look up the answers given by credible researchers. Moreover, one doesn't need to "get" all the technical details one might therefrom obtain; one mostly just needs to understand the themes and context. All that takes is reading/listening comprehension, no math involved. Your summation above also illustrates an application of exactly that assertion.

So, again, kudos. Hopefully more folks here will follow your example of actually applying the scientific method before sharing their conclusions.

 

[eohrnberger]

In the imagery, in order to 'make the stars move through time', all of the following:

The Earth's, rotation,
orbiting the sun that gives us years,
the sun is orbiting the galactic center,
(and probably a couple of more layers of orbits)

All have to be cast into, and taken account of, in a set of equations that reliably predict any one of those star's location at any one time.
This is what I find a rather amazing accomplishment. The mathematics foundation that all this rests on.

 

[Xelor]

In the imagery, in order to 'make the stars move through time', all of the following:

The Earth's, rotation,
orbiting the sun that gives us years,
the sun is orbiting the galactic center,
(and probably a couple of more layers of orbits)

All have to be cast into, and taken account of, in a set of equations that reliably predict any one of those star's location at any one time.
This is what I find a rather amazing accomplishment. The mathematics foundation that all this rests on.

I don't know whether astronomers have determined the orbital path of every stinking star that we can see in the galaxy. Maybe they have, but I doubt it.

More likely is that they've done that for quite a lot of them -- thousands, maybe even millions -- and observed that others move roughly the same way, i.e, comply with the laws of physics (gravity being a big one) and deductively extrapolate the motion of the rest.

As for how they figure out the orbit of any given star, well, that's something a high school student can do provided s/he has the observational tools/data to do so. Obtaining the observational data is the trick, but math for determining a optically visible star's (as opposed to those one must use other parts of the light spectrum to "see") motion it is quite simple. I'm sure you and every other high school graduate has at least heard of the tool used: the Doppler Effect.

• Using spectra to derive motions
• Doppler Effect Equations for Light

 

[eohrnberger]

I don't know whether astronomers have determined the orbital path of every stinking star that we can see in the galaxy. Maybe they have, but I doubt it.

More likely is that they've done that for quite a lot of them -- thousands, maybe even millions -- and observed that others move roughly the same way, i.e, comply with the laws of physics (gravity being a big one) and deductively extrapolate the motion of the rest.

As for how they figure out the orbit of any given star, well, that's something a high school student can do provided s/he has the observational tools/data to do so. Obtaining the observational data is the trick, but math for determining a optically visible star's (as opposed to those one must use other parts of the light spectrum to "see") motion it is quite simple. I'm sure you and every other high school graduate has at least heard of the tool used: the Doppler Effect.

• Using spectra to derive motions
• Doppler Effect Equations for Light

Fair. But in the video presentation the astronomer said that the Gaia space telescope was providing data on billions of stars, so, . . . . probably have a great deal of data there to crunch on.

 

[Xelor]

Fair. But in the video presentation the astronomer said that the Gaia space telescope was providing data on billions of stars, so, . . . . probably have a great deal of data there to crunch on.

Yes, there is a lot of data "crunching" going on, though "looking" is more apt a term because it's observational data collection that's happening. The calculation, the "crunching," is laborious -- there's a ****load of it to do -- but not hard (the calculations themselves aren't particularly complicated; it's high school math).

Don't get me wrong. There's some majorly hard math associated with stellar science, and lots of it, no less. LOL We just don't happen to be here discussing it.


ETA:
Think about Jupiter's some 60 odd moons. How do we know what orbits they take? We look at them and see. It's the same thing with the stars, except they're more of them and they're farther away and they emit their own light, so we use what we know about light (the Doppler Shift) that to tell rather than, say, just simply looking and "tracing a curve." But make no mistake, all they're doing is "tracing a curve" using the Doppler equation. If you graphed a parabola, circle or ellipse, you've done the same thing.

 

[Bullseye]

I'm sitting here watching the show and perusing threads here, watching the show on Galaxies, and it just struck me and I asked, so rather impulsive than thoughtful, I guess. :shrug:

I thought it was a valid question. Xelor's response was a tad condescending and snooty, IMHO.

 

[eohrnberger]

I thought it was a valid question. Xelor's response was a tad condescending and snooty, IMHO.

:shrug: