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General Astronomy >> General Observing and Astronomy

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careysub
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Re: unlearning the constellations new [Re: drollere]
      #5506855 - 11/06/12 12:52 PM

Quote:

...
we all learn the constellations in our novice steps, and these ingrain certain asterisms in mind as if they are equally distant stars appearing at pretty much their absolute magnitudes. this is so far from the truth that it seems necessary to unlearn the constellations in order to make sense of the sky....




When I do outreaches one point I like to make (if they are visible) is to explain the random nature of most constellations, but then point out those that really are physically associated groups of stars, and what it is they are looking at (e.g Orion and the Orion-Eridanus complex; the Ursa Major Moving Group).


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drollere
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Re: unlearning the constellations new [Re: careysub]
      #5508418 - 11/07/12 01:59 PM

i spent the past few nights pursuing the issue of the bright "anchor stars" (per my outline posted above), simply looking at the sky with my eyes rather than with a telescope or binocular. these anchor stars are the starting point for several different avenues of inquiry ... but they need to be, first of all, easily recognizable and useful signposts to the solar neighborhood and galactic landscape.

this is a favorable time of year for the exercise, because the sky presents both many bright stars and a great variety of constellations, as indicated HERE.

my experience turned up the following insights:

1. "recognizing" the constellations is an act of constructive looking. if you simply turn toward a random area of sky (especially if you do not know the compass direction), a few moments of "study" are necessary to recognize the bright stars or asterisms, parse them as constellations, and "trace" them with the eyes.

2. the constructive looking often requires running your eyes over the entire figure, to "connect the dots" of the supposed asterism. this may not seem plausible with a bright or compact asterism such as orion or auriga, but try your luck with cepheus, pisces, aquarius or lacerta. you don't "see" constellations so much as "search for them".

3. taken by themselves, the bright stars define asterisms that are completely unrelated to the traditional constellation figures. the summer triangle (altair, vega, deneb) is a simple example. cygnus is really a "T" shaped asterism -- albireo is both detached and relatively faint. perseus is really a long arc of stars that naturally ends in the pleiades. andromeda is an arc of three bright stars (alpha, beta, gamma). the dipper is salient, and detached from the string of faint stars associated with it.

4. associating faint stars with bright stars seems to make the faint stars brighter. having traced the constellation outline visually (usually, three or four times), the gestalt tends to equalize the stellar brightnesses.

5. there are large gaps in the sky. the area from the pegasus square to diphda or formalhaut is basically empty. so is the area between the auriga pentagon and the dipper. you need dark skies to be able to see the stars in pisces or aquarius, much less trace them as "figures". once you let go of "constellations", these broad dark areas appear remarkable and mysterious.

the local arm presents a beautiful structural transition from deneb to betelgeuse, and, after you've done your naked eye assay of constellations, it's rewarding to scan this arc with a binocular. notice how the texture, density and brightness of the stars changes from the distant star clouds around albireo to the coarser, brighter star fields passing capella. as you do, note the changes in star density, brightness and the appearance of nebulae in relation to the locations of deneb, alderamin, caph, mirfak, capella, elnath and betelgeuse.

i regret i can't make similar observations about southern constellations, but it seems (as one example, and looking at star charts) that the four brightest stars in centaurus and crux form a natural group.

the goal here is to identify conceptually useful groupings of visually bright stars. i found it was actually a bit of concentration and patience to lose the ingrained habit of "seeing" what i have memorized. looking at the sky from different angles, sweeping broad areas or focusing on details, not looking at any specific asterism but taking them all in with indirect vision -- these techniques helped.


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drollere
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Re: unlearning the constellations new [Re: auriga]
      #5508446 - 11/07/12 02:26 PM

Quote:

I do think it impairs your presentation to conflate the humanities and the social sciences with greed and vulgar materialism, and I think distinguishing the two would greatly help your argument. You would then have obviated Tony and Craig's quite well-founded objections.



all i can say is, please read my four points in the post several posts above, and the twenty topic heads in the "book" outline. i don't see any substantive reference to humanities or arts in them.

the theme all along has been to organize our visual recognition of the night sky in a way that leads naturally and intuitively to a recognition of the structure of our galaxy and our place within it.

i have pointed out that the traditional astronomy literature and commercial astronomy guides perpetuate a way of looking at the sky that obstructs rather than facilitates that objective and encourage a fragmented and contextless understanding of astronomy.

all the posts that seek to drag this topic into other issues, are, as i've pointed out, unconstructive and based on poor evidence or faulty reasoning. but no matter. i feel i've been patient in replying to those concerns and, as they are irrelevant to my stated aim, i am not interested to address them further.


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auriga
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Re: unlearning the constellations new [Re: drollere]
      #5509097 - 11/07/12 09:52 PM

Bruce,
This quotation from your earlier post struck me as identifying the arts and the humanities with vulgar materialism:

"to your view that "science arises from culture," i'd rather say that it is actually "science" that has been jeopardized by a focus on the past, and by "cultural" abuses related to the defense of personal prejudices, corporate interests, academic status, political gain and religious beliefs. it's really science that is being derided and denigrated in our culture, while the "arts" of music, theater, painting, film, comedy, rhetoric, grooming fashion and investing that are cultivated and celebrated -- often as lucrative markets and shaped by profit motive."

I disagree with the above quotation and I contend that there is immense value in many things in our history and our culture that are not in themselves science. I think you do your argument a disservice by a needless explicit and implicit derogation of the arts, the humanities, history, and the social sciences.

But the idea of your book strikes me as original, and you are certainly knowledgeable the area of galactic structure, so i am hoping to find quite a bit of value in your forthcoming book.

I will let the matter rest here, and wish you well with your book..

Bill


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CounterWeight
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Re: unlearning the constellations new [Re: auriga]
      #5509712 - 11/08/12 10:50 AM

Bruce,

Thank you for taking the time responding to my post, I am grateful.

Quote:

our eyes look at the hubble images, but our heads organize the images with nothing more sophisticated than bayer's uranometria. the first step is to discard uranometria, unlearn the myths, and approach the sky with fresh and uncluttered eyes.





I am in agreement in many ways - I believe Steve O'meara says something quite similar in his 'Hidden Treasures' book - or at least very much along those lines. Having catalogs and objects that populate them, and not realizing that in the space nearby may be other interesting objects of one stripe or another.

I have encountered similar thinking in other works, though my memory issues prevent an exect recounting. Something ssems to tickle from Shapleys' "Inner metagalaxy" - a book I have 2 copies of and have not re-read in much detail since my gaskets blew out.

I do remember much discussion some time ago (70s?) when there was a large wall poster of a galaxy type as ours is proposed to be with a 'you are here' label / arrow out on one of the arms. Somewhat heated discussion /debate about it being fantasy as most of our galaxy hidden.

You make several points that I think in considering the significant increase in data over the last forty or more years have a lot of merit. Your points about star type / association / grouping - and visual cognition. As an exapmle you refer to Cyg as a 'T' shape and it certainly is ! to me it's back to back right triagles. I've never seen it as a swan or anything else. I suppose I could say same for the squares of Peg, Leo, Herc... Then ther's huge spanning associations I have like this morning Arcturus->Spica->Denebola-Regulus and much more...

As a point I'd like to add that it's quite interesting to look in Burnahms for interesting doubles, then same exercise in NSOG, then type in a search in SkyTools3 pro - and compare results. Not all the data is new but with modern computing the data is being collected and qualified and quantified, sorted, 'binned', and tagged. I'm a bit astonished how much data is available to me! And there are sites like this one which are very interesting.

I think I understand your point is one of both aspect and orintation? If I have that wrong I apologize. Here I am referring to our sun/earth and solar system orientation - then the night sky celestial orientation. I think it simple for folks to understand these days that the sun is on the other side and illuminating the moon and that the planets occupy a certain arc/plane in it as the earth spins and they orbit the sun. I'm using simple in a relative sense.

Plane of our galaxy being somewhat easy to explain at any dark site as it can be visualized and not a problem to state/see that it's the area we look for nebula and clusters and 'neighbors' in the plane. Looking out of plane we see much farther and other galaxies show up on the radar.

Plane of solar system not orinted same as galactic plane.

Here is where to me it gets a bit complicated from a historical perspective and in some ways might get interesting depending on how you look at history, and possibly what someone might believe about history. Here I refer entirely to the constellations of the Zodiac and nearby, not just the star associations used for terrestrial navigation. And here I am unclear on what and if any associations or dissociations are necessary and important. The question of arbitraryness comes to the front? For instance if I say the zodiac is arbitrary, am I then going to say the base x system of circular division also arbitrary? Why 360 deg divided into twelve secions of 30 deg?

Lets say... yes, discard it all. This only because we have a more useful system to replace it. We could conceive of using something based on magnitude / vector of stars relative to one another.

But to get away from a simple x/y orintation and into a vector system might be even more 'modern'. So we can also say goodbye to the Cartesian reference entirely and go to one based in three dimensions instead of two. I think at that point we have discarded all not required historical reference? This aside from re-naming the stars? Here the door opens to even more modern mapping and associations and we could possibly include more modern ideas about spacetime. If we include understanding of absolute and relative magnitude, direction of relative motion, distance and light travel time, area of 'mesh' wrt time and distance... there are many significant changes. We are then looking at the space map in a relativistic sense and not simply as navigators needing simple x/y co-ord's and a clock. IMO then we are looking as navigators of spacetime and not earth surfaces.

If that is the direction you are meaning it's certainly interesting to me.

My objection to discarding the historical perspective has much more to do with my appreciation of history and that what may seem arbitrary to us today in a practical sense still has significant meaning and relevance to our understanding of the great cultures, minds, ideas that brought our understanding and interests this far. I have more than once found myself nearly floored that ancient civilizations created systems that could work at all many thousands of years later, let alone be understood across numerical base systems, writing systems, to the point of inclusion and incorperation. I think that there is a historical perspective to it is hugely significant and important, a fantastic validation of some principals of mathematical and geometric thought.

So where does the historical practice/perspective participate to the point where it should inhibit moving something forward in a constructive sense? In a relativistic and cosmology mapping pretty much everywhere other than names (I think they are useful and practical even after stripping off most other things?)

Apologize for the long post, but just after some clarification in my own thinking in trying to understand the ideas/concepts of necessary and sufficient to create something truely new and useful and illuminating to anyone interested.

Also my apology for numerous typo's.


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drollere
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Re: unlearning the constellations new [Re: CounterWeight]
      #5510035 - 11/08/12 02:08 PM

i am certainly intrigued, even fascinated, by the sentiment repeated here that my proposal to look at the sky with fresh, wide eyes is equivalent to trashing the past, burning books, forbidding ideas, purging texts, policing speech or denigrating culture.

as i said, i decline the opportunity to debate those points further. but i appreciate the demonstration of the grip that tradition holds on the mind.


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Glen A W
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Reged: 07/04/08

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Re: unlearning the constellations new [Re: drollere]
      #5510054 - 11/08/12 02:22 PM

Quote:

i am certainly intrigued, even fascinated, by the sentiment repeated here that my proposal to look at the sky with fresh, wide eyes is equivalent to trashing the past, burning books, forbidding ideas, purging texts, policing speech or denigrating culture.




I think it's a great idea. And one whose time has come. GW


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drollere
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Re: unlearning the constellations new [Re: drollere]
      #5510076 - 11/08/12 02:42 PM

the next step, perhaps the most difficult step, is selecting out of the visible sky the features that can orient the observer and mark out the galactic landscape.

since constellations are by and large unsatisfactory as visual guides (as explained in the previous post), and asterisms have no content as structural features (the stars that compose them can be very widely separated in space), the objective seems to lead to a selection of visually bright stars as the solution space.

"bright" is a loose term (professional astronomers would call a magnitude 15 star "bright"), but given the limitation of naked eye orientation a magnitude cutoff of between 2 to 3 seems about right. for example, stars above magnitude 3 are relatively robust against urban light pollution. in cassiopeia, a salient constellation and asterism, four of the five stars in the "W" are above magnitude 3; similarly, in auriga, all five stars in the pentagon are above magnitude 3; in the dipper, six of the seven stars are above magnitude 3. in contrast, in cepheus, an obscure constellation, only alderamin is above magnitude 3; in lyra, another obscure constellation, only vega is above magnitude 3.

what would a list of "bright" stars, however defined, be used for? at least:

* for orientation to the night sky (e.g., season, sidereal time, direction, latitude)
* for orientation to galactic features (e.g., the galactic center, the local arm)
* as a descriptive sample: what kind of star is a typical bright star?
* as a representative sample: what does the population of stars look like?
* as an enumerative sample: what is a visible example of every kind of star?
* as a local sample: which stars are visible local stars (within X parsecs)?
... and so on.

this is a problem i am still working on. a magnitude cutoff between 2 and 3 seems useful, as it limits the number of stars in the list to around 100 or less. a distance cutoff of about 50 parsecs seems useful, as there are about 50 bright stars within that radius. but a preliminary look indicates that many of the late type (K or M) stars in that list are giant stars. and none of the stars within 50 parsecs is an early type (OB) giant star.

so the challenge seems to be this: develop an intuitive and consistent approach to the selection of landmark stars that are both near and far, intrinsically bright and dim, span the entire HR diagram, and point the way to galactic features ... not so easy, it seems.


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Dennis_S253
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Re: unlearning the constellations new [Re: drollere]
      #5510163 - 11/08/12 03:55 PM

Oh my gosh, the sky is wonderful.

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Tony Flanders
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Re: unlearning the constellations new [Re: drollere]
      #5510266 - 11/08/12 05:10 PM

Quote:

i am certainly intrigued, even fascinated, by the sentiment repeated here that my proposal to look at the sky with fresh, wide eyes is equivalent to trashing the past




Sorry, you are the one who said that it's helpful, maybe even necessary, to "unlearn" the constellations -- in other words, to trash the past.

Nobody has objected to your proposal to view the sky with fresh eyes, and many of us have enthusiastically embraced it. But you seem to be the only one here who finds that the old system obstructs the new one. Most of us have no trouble viewing reality simultaneously from multiple perspectives.

I never visualized the constellations as true physical entities, nor do any of the beginners that I speak to at star parties. In fact, one of the first questions I get is usually "Do those stars really belong together, or is that pattern an accident?" To which I reply, "an accident, of course."


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Dwight J
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Re: unlearning the constellations new [Re: Tony Flanders]
      #5510639 - 11/08/12 09:51 PM

"Unlearning" the constellations would essentially be equivalent to unlearning breathing - not possible. Our brain organizes randomness into patterns at an unconscious level. When I look up, I can't stop seeing patterns and shapes defined by the stars. Constellations/star patterns may vary culturally and historically but they occur across all of them. There may be a way to better describe our place in the cosmos but our innate ability to organize randomness cannot be suppressed.

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CounterWeight
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Re: unlearning the constellations new [Re: Tony Flanders]
      #5510677 - 11/08/12 10:12 PM

Quote:

i am certainly intrigued, even fascinated, by the sentiment repeated here that my proposal to look at the sky with fresh, wide eyes is equivalent to trashing the past, burning books, forbidding ideas, purging texts, policing speech or denigrating culture.

as i said, i decline the opportunity to debate those points further. but i appreciate the demonstration of the grip that tradition holds on the mind.





I think either you missed my point or I muddled it. The past cannot be debated - and not my intention.

My point is what do you intend to retain, if anything at all. This with a mind to not repeating it or simply re-organizing into something purely self suiting.

As I tried to link to... a 3D representaion has ALREADY BEEN DONE. Please convince me you are not re-inventing the wheel.

What are you bringing to the party that others have not already contributed?

It's as though in trying to contribute or even understand... one gets 'dissed' as bound by orthodoxy.

Quote:

the next step, perhaps the most difficult step, is selecting out of the visible sky the features that can orient the observer and mark out the galactic landscape.





who's galactic landscape? What we do know of and have data for... already done, or am I missing something here? I and at least one other responder linked you to it. This for folks that have no access to the web or star chats/atlas? Living in the city and can't see milky way? And it's to be somehow intuitive? All inclusive?

Quote:


what would a list of "bright" stars, however defined, be used for? at least:

* for orientation to the night sky (e.g., season, sidereal time, direction, latitude)
* for orientation to galactic features (e.g., the galactic center, the local arm)
* as a descriptive sample: what kind of star is a typical bright star?
* as a representative sample: what does the population of stars look like?
* as an enumerative sample: what is a visible example of every kind of star?
* as a local sample: which stars are visible local stars (within X parsecs)?






At the risk of repeating myself, this too has been done... at least for anyone willing to look for the information. And that takes surprisingly little effort.

Not re-inventing a perfectly useful wheel - fine.


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derangedhermit
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Re: unlearning the constellations new [Re: drollere]
      #5510715 - 11/08/12 10:31 PM

Quote:

i am certainly intrigued, even fascinated, by the sentiment repeated here that my proposal to look at the sky with fresh, wide eyes is equivalent to trashing the past, burning books, forbidding ideas, purging texts, policing speech or denigrating culture.

as i said, i decline the opportunity to debate those points further. but i appreciate the demonstration of the grip that tradition holds on the mind.




Is there an "ignore this user" function in the forum software? I can't find it.


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mark8888
Carpal Tunnel


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Re: unlearning the constellations new [Re: Tony Flanders]
      #5511015 - 11/09/12 03:50 AM

Quote:


Nobody has objected to your proposal to view the sky with fresh eyes, and many of us have enthusiastically embraced it. But you seem to be the only one here who finds that the old system obstructs the new one. Most of us have no trouble viewing reality simultaneously from multiple perspectives.





I agree with this. It's an interesting topic and a great thread, and I certainly agree that it's important to see the sky intuitively, with our place apparent in the galactic landscape, and any effort to make that easier is a good and valuable thing. But it's as if the poster is saying, humans are incapable of "getting" that two birds are flying at different altitudes if we also note that they appear near each other from our perspective, and if that information proves useful in some way. Of course, we can do both. Most people with even a passing interest in astronomy already understand this and see the sky both ways.


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bumm
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Re: unlearning the constellations new [Re: Dennis_S253]
      #5511847 - 11/09/12 03:18 PM

This has been an intriguing thread. I've contributed a couple of posts, but I'm getting a little lost. I may be missing something, but I get the impression that the OP figures that the constellations somehow detract from gaining a broader understanding of the universe. Surely, if someone figures that the constellations are somehow magically arranged as stellar art, or that the visible stars are all at the same distance, this may be the case, but I've never met anyone with a view of the universe this misleading or primitive.
To the vast majority of starhoppers, the constellations serve as an extremely effective and convenient "coordinate system" for finding things in the sky. One could use RA & dec, but the constellations are essentially engraved on the sky, requiring no other equipment to measure and read.
Does this system somehow stand in the way of gaining a broader understanding? Of course not. If anything, having to look at the sky, with it's different star densities in different areas, the proximity or "avoidance" of certain objects to the Milky Way, the visual structure in the Milky Way, and any number of other variations leads to a greater understanding of the solar system, the galaxy, and the universe for anyone who's curious enough to want to know.
In my personal opinion, one would learn much less about the universe by only finding objects by their RA & dec coordinates, or worse yet, letting a GOTO scope find everything without paying any attention to where the scope is pointed.
And no, I'm not arguing against GOTO...
Marty


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Tom Polakis
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Re: unlearning the constellations new [Re: bumm]
      #5511897 - 11/09/12 03:51 PM

Quote:

This has been an intriguing thread. I've contributed a couple of posts, but I'm getting a little lost. I may be missing something, but I get the impression that the OP figures that the constellations somehow detract from gaining a broader understanding of the universe.




No, it doesn't sound like you're lost at all. That's a good summary of what the OP is insisting is the case.


Quote:

To the vast majority of starhoppers, the constellations serve as an extremely effective and convenient "coordinate system" for finding things in the sky. One could use RA & dec, but the constellations are essentially engraved on the sky, requiring no other equipment to measure and read.




Exactly. With all of their flaws, I find that constellations draw associations similar to states in the U.S. Just as I associate Florida with swamps, New England with rolling hills, and Colorado with jagged peaks, the constellations serve the same purpose. They aid rather than hinder my 3-D perspective of the sky. Ophiuchus is that constellation with the globular clusters due to their position in the galaxy's halo. The Supergalactic Plane cuts through Virgo and Ursa Major, hence all those relatively nearby galaxies.

Knowledge of the constellations and a perspective on the structure of the universe are in no way mutually exclusive. If I didn't embrace both as enjoyable pursuits, I'd be inclined to get another hobby.


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Crossen
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Re: unlearning the constellations new [Re: bumm]
      #5511980 - 11/09/12 05:04 PM

Quote:

If anything, having to look at the sky, with it's different star densities in different areas, the proximity or "avoidance" of certain objects to the Milky Way, the visual structure in the Milky Way, and any number of other variations leads to a greater understanding of the solar system, the galaxy, and the universe for anyone who's curious enough to want to know.




When I read this, it reminded me of W. W. Morgan's story about how he discovered the Perseus Spiral Arm:

"I used to go to Cleveland for a week or so every few months [to meet with J. J. Nassau to work on the identification of Galactic OB stars], for a number of years. Nassau and I did all the classifying. . . . We had a belt I believe 10 degrees wide, as far south as we could get around the sky, and this [provided] the basic catalogue that we used here [at Yerkes Observatory] for taking slit spectrographs of as many of these stars as possible."

"Anyway, in the fall of 1951 I was walking between the observatory and home, which is only 100 yards away. I was looking up at the northern sky, just looking up in the region of the Double Cluster, and it suddenly occurred to me that the Double Cluster in Perseus and then a number of stars in Cassiopeia and even Cepheus--that along there I was getting distance moduli of between 11 and 12. Well, 11.5 is just 2 kiloparsecs, and so I couldn't wait to get over here and really plot them up. It looked like a concentration. . . . . But the hardest thing is to know what's going on if you're in the middle of something. So when I plotted out the Perseus arm, I then plotted out the other stars, and it turned out through the Sun there was this narrow lane parallel to the other one. So that's the way it happened. It was a burst of realization. It was not a question of a reasoned process of steps." (Page 92 of Owen Gingerich's "The Great Copernicus Chase and Other Adventures in Astronomical History.")

Obviously Morgan's knowledge of the constellations helped him visualize what his astrophysical data meant topographically. It also demonstrates how we ourselves can use the constellations in learning Local Spiral Structure. Moreover, many of the constellations are NOT entirely mere chance alignments of stars: Orion looks the way it does in part because almost all its bright stars are members of the Orion Association. Most of the bright stars in Scorpius, Lupus, Centaurus, and Crux are members of the Scorpio-Centaurus Association. The Big Dipper (anciently known as "The Wagon") stands out because five of its seven stars are the core of the Ursa Major Moving Group. Alpha and Beta Aquarii are members of a decayed association. The face of Taurus and the Hair of Berenice are open clusters. Naturally most of the constellations are indeed chance alignments of stars. But enough of them are not that learning the constellations is a very good first step in getting "Galactic depth perspective."

Craig Crossen


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Kfrank
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Reged: 12/20/08

Loc: Northern Colorado
Re: unlearning the constellations new [Re: derangedhermit]
      #5513325 - 11/10/12 03:29 PM

Quote:

Quote:

i am certainly intrigued, even fascinated, by the sentiment repeated here that my proposal to look at the sky with fresh, wide eyes is equivalent to trashing the past, burning books, forbidding ideas, purging texts, policing speech or denigrating culture.

as i said, i decline the opportunity to debate those points further. but i appreciate the demonstration of the grip that tradition holds on the mind.




Is there an "ignore this user" function in the forum software? I can't find it.




I am intrigued and even fascinated by the fact that the OP continues to dismiss those who refuse to jump on his bandwagon as hide bound traditionalists.

Putting forth a controversial proposal, refusing to engage in debate with regard to it and dismissing those who disagree as either simpletons who just don't understand or bound by tradition hardly seems to be the way to get one's point across.

Bruce, I too decline the opportunity to debate this further.


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Mxplx2
sage


Reged: 09/12/12

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Re: unlearning the constellations new [Re: Kfrank]
      #5514051 - 11/11/12 07:37 AM

DANGER!!!

EGOS AT WORK.

ENTER WITH CAUTION!


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drollere
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Re: unlearning the constellations new [Re: Mxplx2]
      #5514432 - 11/11/12 12:50 PM

a simple place to start the list of anchor or critical stars, the bright stars that orient the observer to the galactic landscape, is with local bright stars -- "companion" stars.

this list depends in part on the magnitude cutoff, in part on the distance cutoff, and in part on an inclusion cutoff ... but i've chosen a magnitude of about 2.0, a distance of 10 about parsecs and an inclusion of 10 stars. this yields the selection below:



stars in red are just outside 10 parsecs, but arcturus is useful to mark the north "window" of the galactic pole.

the selection provides two stars in the winter galaxy, and two stars in the summer galaxy, both very bright and distinctive, and a single bright star near the galactic north and south poles. the diagram, which represents the true distances in relation to equatorial north and the points of solstice, shows a nice distribution.

the 10 parsec sphere is the basis for absolute magnitude, so it is useful to describe the magnitude system, its definition as a logarithmic scale, and the fact that a log scale defines our visual sensitivity and perception of brightness.

it's also useful to characterize the close solar neighborhood, for example as an enumeration of *all* stars within that distance. according to the hipparcos-yale-gliese database (documented and available HERE), the enumeration looks like this (spectral type shown as size and color of icon):



remarkably there are 325 stars in HYG within 10 parsecs, half of them at magnitude 11 or fainter, and over 80% of them too faint to see with the naked eye. most of our "neighbor" stars are invisible to binocular assisted eyes and not part of any constellation asterism.

the reason is that most are K and M type stars (small red icons), cooler and less massive than the sun and also much fainter. (far from being an "average" star, the sun is actually above average, and above median.) in fact the hipparcos and gliese surveys suffer the same "brightness bias" that afflicts every branch of astronomy, because the true number of stellar mass objects within 10 parsecs is higher by an unknown but significant amount.

the james webb telescope, optimized for large aperture infrared astronomy, may indicate by how much. in the meantime, a 10 parsec radius defines a sphere of about 4200 cubic parsecs. given only the stars we see, this implies an average distance between 325 stars of about 3 parsecs.


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