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Basic questions about constellations

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#1 dearchichi

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Posted 12 April 2021 - 04:06 PM

Please let me know if I have gotten the below right?

 

1. Constellations, as far as they refer to patches of the sky, are not defined by stars but by IAU boundaries specified by RA,Dec values pegged to a date (like 1/1/1875).

 

2. Once constellations are associated as above, they always map to the same patch of the sky across time (i.e., irrespective of precession etc.). Thus, the shapes of the constellation boundaries do not change with time.

 

3. Stars are not tied to constellations, and can drift in and out of them depending on their proper motions. The latter will also cause changes in the "stick figures" formed of bright stars that presently map to their respective constellations.

 

4. Assuming the plane of the ecliptic does not change with time, the patches of the sky that the ecliptic passes through does not change, and neither do the astronomical zodiacal constellations that the ecliptic runs through nor the ecliptic's orientation within them. This is independent of the obliquity of the ecliptic.

 

Thanks.



#2 havasman

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Posted 12 April 2021 - 04:29 PM

That all looks correct enough. But constellations are human constructs also tied to the societies that choose to select them from the several that are available. Not all human societies made the same patterns of the stars they saw in the sky. Plus, everything in the sky is moving at some rate and moving in relation to our viewing location. So nothing will not change over time.

Constellations are handy location indicators and lovely to look at. But they are time-sensitive, depend on consensus for their existence and can be thought of as either permanent or ephemeral depending on the time scale referenced.


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#3 sg6

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Posted 12 April 2021 - 04:36 PM

Please let me know if I have gotten the below right?

 

1. Constellations, as far as they refer to patches of the sky, are not defined by stars but by IAU boundaries specified by RA,Dec values pegged to a date (like 1/1/1875).

 

2. Once constellations are associated as above, they always map to the same patch of the sky across time (i.e., irrespective of precession etc.). Thus, the shapes of the constellation boundaries do not change with time.

 

3. Stars are not tied to constellations, and can drift in and out of them depending on their proper motions. The latter will also cause changes in the "stick figures" formed of bright stars that presently map to their respective constellations.

 

4. Assuming the plane of the ecliptic does not change with time, the patches of the sky that the ecliptic passes through does not change, and neither do the astronomical zodiacal constellations that the ecliptic runs through nor the ecliptic's orientation within them. This is independent of the obliquity of the ecliptic.

 

Thanks.

1 is a bit fuzzy. The original constellation was simply that particular pattern. The Greeks, Romans, Babylonians, Mayans etc did not say that this area of the sky is the boundry to Lyra or whatever. They just saw Lyra. The boundaries as most likely a modern thing and created by a committee. The boundry is not really for the constellation but the much fainter ones and is a way to designate them. If some faint insignificant one lies between Cassiopeia and Andromeda someone drew a line and said this side is Cass the other is And, so that star has some designation and is in And (say), say And 14962. The 14962nd faintest star on the side of the line we call the Andromeda boundry. The areas/boundry is not specifically for the recognised constellation stars, they are easy.

 

2 They will change, when the next committee comes along. In a way they have to. Any group that spends say 5 years and $10 million considering such has to make a change. They cannot say after 5 years and $10m we have decided to leave things just as they were. Thanks for the money, by the way.

 

3 Stars move, proper motion, see Gaia project. However in yours and my lifetime you will not be able to tell. Go look up Barnards Star (I think). And when they do move sufficent then by then the actual constellation will by defination have changed and some other committee will redraw the boundries.

 

4 Not overly sure about the ecliptic. I wonder if your idea of "time" is the same as mine. Who can be sure what the next million years might bring change to. And a million years is a short period of time. As the moon slowly moves away then its influence on the earth reduces and our stability will reduce so I could see the ecliptic changing. Timescale 50 million years maybe, could be less.

 

Concerning a "committee" - how many stars make up the corners of the Great Square of Pagasus ?

If you say the obvious 4, one at each corner then you are wrong, there is "offically" only 3.

A committee decided that one was now solely part of Andromeda. So now by a committee decision the Great Square of Pagasus is a square of 3 stars, one at each corner of the square. lol.gif  lol.gif  lol.gif 


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#4 barbarosa

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Posted 12 April 2021 - 05:08 PM

Are constellations any longer important or relevant to astronomy, either professional or recreational? I propose that they are not.

 

I know that many of us at a young age learned something about constellations, from out parents, in school or in the Scouts. We got a smattering of the tie to mostly Greek and Roman mythology. And that was fun and provided an historical and cultural perspective. One could see at least a few constellations (or a part of them) even from the city. 

 

But times change, the population is vastly greater than when I was a child, and cities and suburbs are lighted to a much higher level. Interstate highways are rivers of light, dimming the stars like linear towns. Today far fewer people look at the night sky, let alone see the Little Dipper/Ursa Minor or use Cassiopeia to find Andromeda. Now where it is possible to see a constellation I hope that children will continue to learn a name or two and be able to pick them out in the night sky. Find the dipper, find Polaris and the door is open for some actual science. But that's not so much the case with most of the constellations.

 

The constellations have no scientific importance, no objective existence and are not an operative part of observational astronomy. I know some some of us still like to star hop and identify targets by reference to the constellation, but they are not essential to finding targets or understanding them or appreciating them in a personally enjoyable way. A go to setup is much more useful.

 

In short they are irrelevant anachronisms, not deserving of any study as astronomy nor of international agreements. If you can't see them, don't use them  for anything, and there is no science involved in them, then it is time to consign them to a footnote or a cultural anthropology freshman text book.


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#5 Starman1

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Posted 12 April 2021 - 07:48 PM

Please let me know if I have gotten the below right?

 

1. Constellations, as far as they refer to patches of the sky, are not defined by stars but by IAU boundaries specified by RA,Dec values pegged to a date (like 1/1/1875).

 

2. Once constellations are associated as above, they always map to the same patch of the sky across time (i.e., irrespective of precession etc.). Thus, the shapes of the constellation boundaries do not change with time.

 

3. Stars are not tied to constellations, and can drift in and out of them depending on their proper motions. The latter will also cause changes in the "stick figures" formed of bright stars that presently map to their respective constellations.

 

4. Assuming the plane of the ecliptic does not change with time, the patches of the sky that the ecliptic passes through does not change, and neither do the astronomical zodiacal constellations that the ecliptic runs through nor the ecliptic's orientation within them. This is independent of the obliquity of the ecliptic.

 

Thanks.

1) Correct.  As defined by the IAU and the lines are subject to precession.  They are arbitrary.

2) Again correct.

3) Well, yes, if a star's proper motion took it across a line.  This is unlikely in a human lifetime and possibly longer.

None of the highest proper motion stars is near a constellation boundary.

Proper motion will distort the stick figures over time, but we're talking LOOOOOOOOONG periods of time, here.

4) The ecliptic does change with time because the precession of the poles is not an exact circle--after the 26,000 year cycle, the pole will not return to the same exact coordinates.

So the ecliptic is always wobbling over a very long time frame relative to the background stars.  The 13 constellations of the zodiac may change if we draw new patterns in 500 years, but that 

won't matter to astronomy at all.

 

The sun is also moving itself, and over a long enough period of time, it will distort the constellations.

 

So the IAU boundaries for the constellations is a temporary thing--maybe lasting a couple hundred years at most until the lines at the boundaries become so skewed relative to lines of RA and DEC

that the boundaries need to be redrawn.

When that occurs, a lot of stars may suddenly find themselves in different constellations.  That's all arbitrary anyway, since maybe only the brightest 50 stars are referred to by a constellation designation

and the rest have numbers from huge catalogs of stars, and there isn't a reason to change those designations if the constellation lines change.


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#6 Tony Flanders

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Posted 12 April 2021 - 08:09 PM

So the IAU boundaries for the constellations is a temporary thing--maybe lasting a couple hundred years at most until the lines at the boundaries become so skewed relative to lines of RA and DEC
that the boundaries need to be redrawn.


I don't see why. The constellation boundaries are already noticeably skewed with respect to lines of RA and Dec, and that fact doesn't bother anybody. There seems to be no benefit whatsoever to redefining the constellation boundaries, and a great deal of disadvantage. People will just get used to the fact that the constellation boundaries don't line up well with RA and Dec.

 

Constellations will undoubtedly have less importance to professional astronomers as time goes on. But it's worth remembering precisely why the IAU got into the constellation business in the first place. Variable star designations include the constellation that contains the star, e.g. T Tauri or V361 Orionis. So the constellation boundaries needed to be defined precisely in order to figure out what designation should be given to newly discovered variable stars.

 

A more interesting question to me is how long the RA/Dec system will last. For the most precise work, celestial positions are actually defined with respect to distant quasars, not with respect to Earth's equator and pole. It seems a little silly to use a coordinate system that needs to be tweaked every half century or so. It will be interesting to see when the next tweak occurs -- assuming that it occurs at all. Given the increasing obsolescence of equatorial mounts, perhaps it would make sense just to stick with J2000.0.


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#7 russell23

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Posted 12 April 2021 - 08:41 PM

Are constellations any longer important or relevant to astronomy, either professional or recreational? I propose that they are not.

 

I know that many of us at a young age learned something about constellations, from out parents, in school or in the Scouts. We got a smattering of the tie to mostly Greek and Roman mythology. And that was fun and provided an historical and cultural perspective. One could see at least a few constellations (or a part of them) even from the city. 

 

But times change, the population is vastly greater than when I was a child, and cities and suburbs are lighted to a much higher level. Interstate highways are rivers of light, dimming the stars like linear towns. Today far fewer people look at the night sky, let alone see the Little Dipper/Ursa Minor or use Cassiopeia to find Andromeda. Now where it is possible to see a constellation I hope that children will continue to learn a name or two and be able to pick them out in the night sky. Find the dipper, find Polaris and the door is open for some actual science. But that's not so much the case with most of the constellations.

 

The constellations have no scientific importance, no objective existence and are not an operative part of observational astronomy. I know some some of us still like to star hop and identify targets by reference to the constellation, but they are not essential to finding targets or understanding them or appreciating them in a personally enjoyable way. A go to setup is much more useful.

 

In short they are irrelevant anachronisms, not deserving of any study as astronomy nor of international agreements. If you can't see them, don't use them  for anything, and there is no science involved in them, then it is time to consign them to a footnote or a cultural anthropology freshman text book.

It is funny that Garrett Serviss basically said the same thing in his 1888 book “Astronomy with an Opera Glass”.   Here are two images of a few lines from the 1st two pages of my copy of the book:

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#8 KBHornblower

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Posted 12 April 2021 - 11:18 PM

1) Correct.  As defined by the IAU and the lines are subject to precession.  They are arbitrary.

2) Again correct.

3) Well, yes, if a star's proper motion took it across a line.  This is unlikely in a human lifetime and possibly longer.

None of the highest proper motion stars is near a constellation boundary.

Proper motion will distort the stick figures over time, but we're talking LOOOOOOOOONG periods of time, here.

4) The ecliptic does change with time because the precession of the poles is not an exact circle--after the 26,000 year cycle, the pole will not return to the same exact coordinates.

So the ecliptic is always wobbling over a very long time frame relative to the background stars.  The 13 constellations of the zodiac may change if we draw new patterns in 500 years, but that 

won't matter to astronomy at all.

 

The sun is also moving itself, and over a long enough period of time, it will distort the constellations.

 

So the IAU boundaries for the constellations is a temporary thing--maybe lasting a couple hundred years at most until the lines at the boundaries become so skewed relative to lines of RA and DEC

that the boundaries need to be redrawn.

When that occurs, a lot of stars may suddenly find themselves in different constellations.  That's all arbitrary anyway, since maybe only the brightest 50 stars are referred to by a constellation designation

and the rest have numbers from huge catalogs of stars, and there isn't a reason to change those designations if the constellation lines change.

3) As it happens, Alpha Centauri is very close to the IAU boundary with Circinus, but fortunately is moving away from it.  If we backdate the large proper motion some 300 years we will find the star across that line, but that would have been before Circinus was invented, let alone charted with the 1930 boundaries.  If I am not mistaken, this star has been considered part of Centaurus for a much longer time.



#9 Dave Mitsky

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Posted 14 April 2021 - 05:54 PM

Precession and the zodiac is discussed at https://www.astronom...ith-precession/ and https://www.livescie...gical-sign.html



#10 gnowellsct

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Posted 14 April 2021 - 07:07 PM

It seems a little silly to use a coordinate system that needs to be tweaked every half century or so. It will be interesting to see when the next tweak occurs -- assuming that it occurs at all. Given the increasing obsolescence of equatorial mounts, perhaps it would make sense just to stick with J2000.0.

There's no need to stick to J2000.  The tweak occurs every time software is booted up. So you could say J2019 if you wanted to.  People would know to set the computers to 2019 to see the EXACT spot to which you refer.  Or you can recess to 2000 or 1950 in your computer.  When I boot up my Argo Navis and input NGC 2420 in my computer it takes me to the exact precessed coordinates for "epoch of date." (meaning today's date) If I want to check it against paper published coordinates I would set the internal date back to 2000 (or even 1950).

 

But my Argo Navis and Planetarium software always boot to "Epoch of Date" which means they've done all the precessions and calculated the planet positions etc.

 

So there is no particular need to worry about the fifty year reset except for paper based publications like U2000.  By 2050 there will be precious few of those.  I don't know whether, if one is a professional astronomer today, one is obligated to report older coordinates or just put down the epoch of date of when you are writing.  I suppose I could ask.  I know quite a few professional astronomers as I'm sure you do too.

 

But actually the one who knows the most about all this positional stuff is likely Brian Skiff.  At least he has been my resource in the past.  If I found something unusual and read the coordinates off my Argo Navis and reported it to somebody, I would note it as "epoch of date."  But it would be sort of silly.  My pointing is accurate to about 3 to 5 arc minutes, so no matter what positional date I use it will be within the margin of error.

 

More fundamentally, it has nothing to do with equatorial mounts.  Alt-az coordinates are always changing.  They can only be used on an on-going basis if converted from RA Dec databases.  If you're saying that there will be an alternative grid established by quasars and alt-az mounts with ultra fine resolution encoders, well, I suppose so!    

 

For the moment, there may be amateur class alt-az instruments that offer the precision control of a GEM but I haven't seen one.  On the other hand the instrument turnover in my club is low.  But the dob go-to is pretty clunky, the fork mounted gems are extraordinarily heavy and not particularly stable, and polar alignment solves field rotation which otherwise needs a gizmo.  

 

Might be nice to see GEMs disappear though.  I get tired of slinging counterweights and have been intrigued by other designs.  But in field use you have to plan on functionality if the power disappears.  If you have a scope held up by electric servos and you lose power, that's a bad scene.  Given the frequency with which I've seen wire failures in my own and others' equipment, it is definitely something I keep in mind.

 

Greg N



#11 Tony Flanders

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Posted 14 April 2021 - 08:30 PM

I said:
 

A more interesting question to me is how long the RA/Dec system will last. ... It seems a little silly to use a coordinate system that needs to be tweaked every half century or so. ... Given the increasing obsolescence of equatorial mounts, perhaps it would make sense just to stick with J2000.0.


And gnowellsct replied:
 

There's no need to stick to J2000.  The tweak occurs every time software is booted up ...


Ah, I should have been more precise. I should have said "given the increasing obsolescence of mechanical setting circles on equatorial mounts." If you are using mechanical setting circles, you need to know the actual apparent RA and Dec of an object in the equinox of date. Of course if you're using an electronic system you can let the electronics take care of it.
 

So there is no particular need to worry about the fifty year reset except for paper based publications like U2000.


But that's not true at all! It's the electronic publications -- like the GAIA or PGC databases -- where the choice of a standard coordinate system really matters. The fact that they are constantly growing and changing makes it all the more important to have a single standard coordinate system for all the data.



#12 weis14

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Posted 14 April 2021 - 09:36 PM

Are constellations any longer important or relevant to astronomy, either professional or recreational?


Yes! I agree that there is no scientific need for the constellations, but that doesn't mean that a well-rounded amateur astronomer should ignore the myth and romance behind the constellations.

Some of the best attended sessions at outreach events are tours of the constellations. A good tour will note the name and shape of the constellations and a few interesting objects within them. In my opinion, a great tour will sprinkle in a few myths, some romance, and maybe discuss a little cultural significance along the way.

Let's be honest, aside from the occasional submission to the AAVSO or citizen science project, there is no science going on. Most of us are basically stamp collectors, but with the exception that most of our logs or images are even less valuable than stamps.

We dutifully note our observations of objects (or image them) and talk with others about techniques or ways to do it better. I've been observing for 25 years and have done exactly zero science, at least in the way that I define science. As someone with extensive training in engineering and science, I'm confident that the most basic field lab report has more science than I've done on my entire astronomy "career". There has been a lot of electrical and controls engineering over the last 25 years, but no astronomy-related science.

Thus, at some level, most of us are just collectors of astronomical trophies. No one has to learn the cultural importance of the constellations, but for those that do, it is no less a valid part of amateur astronomy than hunting down a few more faint galaxies so you can put them in your log. In fact, the myths might even be a good story to tell when you are out camping or taking an evening stroll under darkening skies. Your companions might not be interested, but they probably won't be interested in the latest Arp galaxy you spotted with averted vision in your 12 inch dob either.

Thus, I'm a firm believer that a discussion of some of the brighter and more famous constellations should be in introductory amateur astronomy books and that most amateurs would benefit from reading a good reference book on the history of the constellations, or at least keeping it on the shelf for situations when your curiosity is aroused.
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#13 Katharine

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Posted 14 April 2021 - 10:28 PM

Slightly related-- but I'm intrigued by AL's Alternate Constellation Observing Program.  I'll never manage to complete the program-- not with the sky geography/location skills, nor the skies, that I have (or lack, if you prefer), but I'm thinking about studying up all of the "academic" parts.  Might make an interesting presentation for my club some day, too.


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#14 Starman1

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Posted 15 April 2021 - 02:33 PM

As an aside, I do a fair amount of observing by limiting my DSC to a particular constellation.

Quite often, the DSC points to an object that appears far away from the stick figure that connects the brighter stars.

To be specific, when an object is more or less half way between stick figures, the only way I'd ever know what constellation it was in

would be to refer to a printed star atlas that has constellation boundaries shown or where the DSC identified what constellation it was in.

 

I bring that up to point out that knowing what constellation an object is "in" is fairly unimportant.  The only reason I can think of where knowing makes sense

is when you are planning an observing session and you want to stick to the meridian or near it by picking a constellation there.

Other than that, the constellation boundaries, even on a printed atlas, are completely irrelevant, whatever the Julian date. 

"Somewhere in between that figure and that figure" is close enough.  



#15 BillP

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Posted 16 April 2021 - 10:17 PM

The constellations have no scientific importance, no objective existence and are not an operative part of observational astronomy. I know some some of us still like to star hop and identify targets by reference to the constellation, but they are not essential to finding targets or understanding them or appreciating them in a personally enjoyable way. A go to setup is much more useful.

 

In short they are irrelevant anachronisms, not deserving of any study as astronomy nor of international agreements. If you can't see them, don't use them  for anything, and there is no science involved in them, then it is time to consign them to a footnote or a cultural anthropology freshman text book.

 

I do not agree with this in the slightest.  Constellations are based in our cultures and in our history as a species.  Losing sight of your culture and history is never a good thing.  We are human beings and what really defines us is our consciousness which is guided by the inseparable combination of our intellect and emotions.  Emotions are core to our being and without them we are nothing.

 

Constellations are also the landmarks of the sky.  To say they are useless and should be ignored and forgotten is paramount to saying we should all ignore street signs, visible landmarks, our own cognitive maps of our environments simply because we have an electronic device to guide us only knowing and needing latitude and longitude to guide us around - ridiculous.  So never know where you are by looking and instead only know my your electronic map?  Ludicrous!  When I go out at night I can look up and know where all the DSO are because I know the landmarks.  I do not need any automation crutch.  If I am doing science then yes, offer the celestial coordinates.  But 99% who undertake this hobby DO NOT do it to conduct scientific research!!  And those who lean on automation to be their "smarts" to find things not only might not know or need the constellation, they also might not know or need the celestial or galactic coordinate systems either, so for them you can relegate those more systematic and scientific approaches to just footnotes as well.

 

Constellations are critical to one knowing their place visually with their eyes in the universe.  When I look up and see the Moon I know exactly where the Sun is in 3D space and when I look up at the sky I instantly know where I am looking relative to our own galaxy and whether it is above the plane or below the plane away from the core or towards the core, etc.  With knowledge and use of the landmarks of the constellations I also know where all the celestial objects are that I observe.  Without the landmark of the constellations and the knowledge of them I would not be able to do that without some device to depend on and why would one ever want to be in a position like that in life?

 

For precision in research and uniformity of scientific discussion one needs to use a coordinate system.  For every other night-tonight activity under the stars the constellations are far more natural, intuitive and reasoned approach.  When I navigate from home to the store or to a friend or relative's house I do not need coordinates nor do I need to rely on external devices to assist me, instead it is encoded with the cognitive map of my mind that utilizes visual references and landmarks.  Similarly, when I decide to visit through observation celestial objects, I also do not need coordinates or external devices to guide me there because with the landmarks of the constellations they are encoded within the cognitive celestial map of my mind.

 

Constellations are very much important and shall never be ignored.  They are ingrained in visual amateur astronomy and respected even by the scientific community for outreach and even within their databases when amateur contribution to data is relied upon (e.g., with double stars the USNO who is the keeper of double star data by the IAU associates in their DB the constellations each star system resides in).


Edited by BillP, 16 April 2021 - 10:20 PM.

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#16 kel123

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Posted 17 April 2021 - 12:02 AM

Are constellations any longer important or relevant to astronomy, either professional or recreational? I propose that they are not.

I know that many of us at a young age learned something about constellations, from out parents, in school or in the Scouts. We got a smattering of the tie to mostly Greek and Roman mythology. And that was fun and provided an historical and cultural perspective. One could see at least a few constellations (or a part of them) even from the city.

But times change, the population is vastly greater than when I was a child, and cities and suburbs are lighted to a much higher level. Interstate highways are rivers of light, dimming the stars like linear towns. Today far fewer people look at the night sky, let alone see the Little Dipper/Ursa Minor or use Cassiopeia to find Andromeda. Now where it is possible to see a constellation I hope that children will continue to learn a name or two and be able to pick them out in the night sky. Find the dipper, find Polaris and the door is open for some actual science. But that's not so much the case with most of the constellations.

The constellations have no scientific importance, no objective existence and are not an operative part of observational astronomy. I know some some of us still like to star hop and identify targets by reference to the constellation, but they are not essential to finding targets or understanding them or appreciating them in a personally enjoyable way. A go to setup is much more useful.

In short they are irrelevant anachronisms, not deserving of any study as astronomy nor of international agreements. If you can't see them, don't use them for anything, and there is no science involved in them, then it is time to consign them to a footnote or a cultural anthropology freshman text book.


This one is a screed against constellations. lol

I think you are totally wrong that constellations have become useless . Constellations are as useful and as interesting as ever.

Most amateur astronomers or observers do not use goto mounts. They still need the constellations to recognize parts of the sky to search for their objects.

If you cannot tell the Orion constellation, how do you know where to locate the Orion Nebula?

If you cannot tell the Lyra constellation, how do you know where or how to locate Vega.

Everyone doesn't have to carry a goto mount on their head every time, even if they own one. There are multitudes of naked eye objects in the sky; how do you locate them with now idea of constellations? How do you know where to search for Bode's galaxy with a pair of binoculars if no one told you it is close to the big dipper?

You need to understand that some things in life are si engrained in the history of humanity that they cannot be "cancelled".

The stars will form the same patterns throughout your lifetime. There is nothing you can do about them. We cannot wake up one morning and scientists say " constellations are no more". No proclamation will clean off the star patterns from the sky.

After all, it is not like constellations are hindering anyone. It is what it is.
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#17 zleonis

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Posted 19 April 2021 - 10:23 PM

Most amateur astronomers/observers have probably developed some sort of mental framework to organize the sky, and to the extent that 'constellation' means 'prominent asterism' I agree that it's reasonably useful to be able to be able to refer to Orion, etc. But many of the constellations as they are currently defined seem almost designedly unsuited to organizing the sky, either because they extend over an entire night's worth right ascension (Hydra, Eridanus, whatever is going on with Serpens) or (and) because they aren't actually constellations in the sense of coherent groupings of stars (Vulpecula? Sextans??).

I suppose practically, although I'm a sucker for the paragraph on the history of the constellation, and get mildly intrigued when a star from a far-off southern constellation makes its brief appearance in my sky etc., the constellations don't necessarily play a major role in how I think of the sky. In my head. I sometimes think of constellations by their brightest star ('epsilon lyrae is a remarkable pair of double stars in Vega', my internal thinking weirdly goes). And I doubt I'm alone in mentally binning prominent objects with prominent nearby constellations in defiance of boundaries - M 104 being in Corvus, M3 in Bootes, and NGC 3115 in, of course, Alphard.

Probably the main reason to be familiar with the constellations is that so many observing guides are organized that way. Burnham's for one, and while the first two volumes of Night Sky Observer's Guide are divided by right ascension, within each volume they're broken down by constellation. Even Annals of the Deep Sky is organized by constellation. Are there observing guides that are organized according to other principles?

Edited by zleonis, 19 April 2021 - 10:59 PM.


#18 Tony Flanders

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Posted 20 April 2021 - 06:26 AM

Probably the main reason to be familiar with the constellations is that so many observing guides are organized that way. Burnham's for one, and while the first two volumes of Night Sky Observer's Guide are divided by right ascension, within each volume they're broken down by constellation. Even Annals of the Deep Sky is organized by constellation. Are there observing guides that are organized according to other principles?


Sure, there are lots of ways to organize an observing guide. Guides to the Messier objects are usually organized by Messier number. And observing lists are usually organized by RA.

But if you want to divide the night sky into a reasonable number of two-dimensional pieces, it would be silly to invent your own system when the constellations already serve that purpose.

True, Hydra is so long that objects in one part of Hydra may be nowhere near objects in another part. But that is a very rare exception to the rule. Generally, the logistics of observing all the objects within any given constellation are pretty much the same.


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#19 Javier1978

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Posted 20 April 2021 - 07:42 AM

Are constellations any longer important or relevant to astronomy, either professional or recreational? I propose that they are not.

 

I know that many of us at a young age learned something about constellations, from out parents, in school or in the Scouts. We got a smattering of the tie to mostly Greek and Roman mythology. And that was fun and provided an historical and cultural perspective. One could see at least a few constellations (or a part of them) even from the city. 

 

But times change, the population is vastly greater than when I was a child, and cities and suburbs are lighted to a much higher level. Interstate highways are rivers of light, dimming the stars like linear towns. Today far fewer people look at the night sky, let alone see the Little Dipper/Ursa Minor or use Cassiopeia to find Andromeda. Now where it is possible to see a constellation I hope that children will continue to learn a name or two and be able to pick them out in the night sky. Find the dipper, find Polaris and the door is open for some actual science. But that's not so much the case with most of the constellations.

 

The constellations have no scientific importance, no objective existence and are not an operative part of observational astronomy. I know some some of us still like to star hop and identify targets by reference to the constellation, but they are not essential to finding targets or understanding them or appreciating them in a personally enjoyable way. A go to setup is much more useful.

 

In short they are irrelevant anachronisms, not deserving of any study as astronomy nor of international agreements. If you can't see them, don't use them  for anything, and there is no science involved in them, then it is time to consign them to a footnote or a cultural anthropology freshman text book.

 

I don't have much interest in studying constellations from a historical perspective, but they are my way to navigate the night sky. Some of they make sense to me, like Scorpio, Orion, Geminis, the Southern Cross (I know this is a though one for many observers), and some of them make no sense. But, knowing that geometrical shape named Corvus enables me to find DSOs in matter of seconds, and knowing what is available to observe in the neighborhood.  Since I'm pretty bad at geometry, I prefer calling that shape Corvus rather than the trapezoid (maybe?).


Edited by Javier1978, 20 April 2021 - 07:43 AM.


#20 Andrew Brown

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Posted 20 April 2021 - 08:12 AM

Are constellations any longer important or relevant to astronomy, either professional or recreational? I propose that they are not.

 

I know that many of us at a young age learned something about constellations, from out parents, in school or in the Scouts. We got a smattering of the tie to mostly Greek and Roman mythology. And that was fun and provided an historical and cultural perspective. One could see at least a few constellations (or a part of them) even from the city. 

 

But times change, the population is vastly greater than when I was a child, and cities and suburbs are lighted to a much higher level. Interstate highways are rivers of light, dimming the stars like linear towns. Today far fewer people look at the night sky, let alone see the Little Dipper/Ursa Minor or use Cassiopeia to find Andromeda. Now where it is possible to see a constellation I hope that children will continue to learn a name or two and be able to pick them out in the night sky. Find the dipper, find Polaris and the door is open for some actual science. But that's not so much the case with most of the constellations.

 

The constellations have no scientific importance, no objective existence and are not an operative part of observational astronomy. I know some some of us still like to star hop and identify targets by reference to the constellation, but they are not essential to finding targets or understanding them or appreciating them in a personally enjoyable way. A go to setup is much more useful.

 

In short they are irrelevant anachronisms, not deserving of any study as astronomy nor of international agreements. If you can't see them, don't use them  for anything, and there is no science involved in them, then it is time to consign them to a footnote or a cultural anthropology freshman text book.

Cancel culture in action.


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#21 kel123

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Posted 20 April 2021 - 08:43 AM

I have got quite a few people to be familiar with the night sky, courtesy constellations. They have been excited to learn how to navigate the sky while using star patterns as landmark.

How might you teach a newbie to navigate the sky by RA?
I never knew there are people out there that hate constellations. I don't get it.
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#22 Starman1

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Posted 20 April 2021 - 09:17 AM

This is the way the older books used to connect the dots  in Aquila:

https://www.alamy.co...um=1&flip=0&pl=

It was described as the Eagle flying north while the Swan (Cygnus) flew south through the Milky Way.

I grew up a birder, and to me it never looked like an Eagle, but it did resemble a Swift:

https://en.wikipedia...Spain-8_(1).jpg

 

Virgo was never a Virgin,  It was a Sperm Whale:

(head on the left, tail on the right)

https://www.touchofm...AyABEgL1AvD_BwE

 

Over the years, I have taught many people to remember the stars by showing them the connect the dots patterns.  One fellow told me in an email not long ago that he remembered the Sperm whale and sees it every Spring.

We are all human, so have pareidolia and see patterns when things are randomly put in our field of vision.  Connecting the dots tells us which way is north, or west, or south, and can tell us the time of night and the season.

And it's not just humans--there are birds that migrate at night by the stars, so it is likely they see patterns too.

 

It's correct that such patterns have little scientific relevance, but even to a professional astronomer, saying something is in Virgo places it in the sky and tells him/her when it might be visible for study.  You wouldn't apply for the use of an

observatory scope to study an object in Virgo in September, for example.  So there is still some use to the constellations as a placement-in-the-sky tool.

 

I've seen the connect-the-dots patterns change 3 or 4 times in my life as "new" methods connected the dots differently, but even though people see the patterns differently (largely due to light pollution), Virgo is still Virgo,

and even if Virgo were called "The Whale", it would still be placed where it is and its location near the equinox would still have relevance for study.

 

So, whatever the names, whatever the patterns you see, wherever the dividing lines are placed, there is relevance to the constellations because they tell you where things are in the sky.  

I suppose you could remember the RA of about 12 hours and remember that was half way around the sky from the Vernal Equinox, but where is the "art", or "poetry" in that?

Man does not live by bread alone.

 

With my apologies to Sarah Williams (I did not remember I read her poem so many years ago), I penned this poem:

 

Summer and Thoughts of Mortality

 

The Summer skies return, now girded with the heat,
And once again the Dark Horse prances ‘cross the sky.
This silver carpet is a feast of tiny points:
My soul is blessed with joy: the stars my eyes anoint;
Vega’s fires ‘cross light years come my eyes to greet;
The Swan flies on its winged way till Eagle meet.
Within their feathered arms are kept that light and dark--
The blackness of the Rift against the astral shine.
But all things must end their days—seasons, nights and lives--
The Hunter’s majesty will triumphantly rise,
And soon the cold will creep into my flesh and reign;
I’ll close my eyes and never see the stars again.
Though death is black against the light of life so stark;
My soul has loved the night too long to fear the dark.


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#23 t_image

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Posted 23 April 2021 - 07:10 AM

I rejoice the OP has interests enough to ask such thoughtful questions!!!!It seems sad to me such a current standard of reference is losing subscribers.frown.gif

My 'experience' consists often of interacting with others at darksites that either have knowledge of or are willing to learn a common language where we can easily refer to segments of the current sky above us.

I feel sad that naysayers are out alone without ever the need for common reference other than 'over there' or 'let me shine my laser pointer' etc.etc.

I get the real life challenges as I decided once to map out the 88 myself on paper, but such added value to my experience and appreciation of the heavens.

The hostility towards such just makes me wonder if those ranting are just making excuses for sloth, and instead just desire to spend 'worthwhile time' staring at their phones to see the latest of what soandso said about x,y,z on tweetgrambook.

Whatever.takes all kinds. but a dogmatic deconstruction of an available set of standards for common dialogue lacks basic reason and is self-contradictory.My opinion.

Maybe the IAU should develop a team of constellation 'evangelists'?



#24 kel123

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Posted 23 April 2021 - 09:22 AM

I think sometimes, some of us humans crave complexity. You see it here on CN where some members try to encourage newbies into more complex setups from the beginning .

 

Some out there might feel that it is just too easy to navigate the night sky with constellations, so why not make it more difficult by using only coordinates instead. 

 

I learnt a lot about the night sky as a kid. I was always excited to make out the star patterns  and find naked eye objects. I looked out for various constellations at different times of the year.

 

Imagine telling me as a kid to only use RA and Dec to find things in the sky . I might be able to navigate the sky that way today but this is because I already know the sky by getting past some stages. This is why there is a level of difficulty in every subject.  You don't do away with the lower levels because you have gone past them.

 

You don't throw away the umbrella because you are no longer getting wet. You certainly don't throw away the ladder after climbing.


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#25 RobbC

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Posted 28 April 2021 - 12:10 AM

Are constellations any longer important or relevant to astronomy, either professional or recreational? I propose that they are not.

 

When sitting by a campfire or lying on a blanket looking up at the stars, a good working knowledge of the constellations and their associated myths and the romance therein are indispensable to picking up chicks.   


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