Constellation shapes?

ThunderChild (Chris) · #1 15-03-2006, 09:03 AM

I was looking at my large Chandler planisphere last night and noticed that the lines drawn to make up the constellations are not the same as other sources I've seen. For instance, if I use my book "A walk through the southern sky", Centarus is quite markedly different - not just in the way the same stars are joined together, but they even use some differemnt stars.

This got me thinking : Has the Chandler just approximated constellation lines due to size constraints? Or are the shapes and make-ups of constellations not an exact science? Is there room for different opinions from source to source?

I had just made the assumtion that they were set in stone. Perhaps I was wrong there.

GrampianStars (Rob) · #2 15-03-2006, 09:18 AM

there should be aussie Constellation shapes
like the dingo, emu, big bad bunny

that way we would n't have to turn our atlas upside down

vespine · #3 15-03-2006, 10:12 AM

I never thought of that. I definitely noticed the lines differ from source to source. I have absolutely nothing to base my opinion on but I always just assumed those lines were just printed there to be 'guides' used to group the stars together, rather then any kind of 'official' shape or map or something... I always thought the shapes had to came from your imagination....

Vermin (Tom) · #4 15-03-2006, 10:20 AM

I'm not sure if there is a standard for the connecting lines, but the constellation boundaries are well defined and should be the same.

ThunderChild (Chris) · #5 15-03-2006, 10:53 AM

Quote:

Originally Posted by Vermin

I'm not sure if there is a standard for the connecting lines, but the constellation boundaries are well defined and should be the same.

Thanks Vermin. Yeah, I can see that the connecting lines may differ (but I would have thought they would be standard too), but surely the same stars would be used?

If anyone's interested, when I get home I'll scan an example from both and put them here to show what I mean.

I was thinking of drawing in some lines onto my mag7 charts that I printed out - and while they're mainly of use to get you looking in the right part of the sky, I'd like to know if there's a "correct" or "official" definition to the constellations - just for my own interest if nothing else.

ving (David) · #6 15-03-2006, 10:53 AM

something i learned at kindy was there is no right and wrong in join the dots, it just art

ThunderChild (Chris) · #7 15-03-2006, 01:03 PM

Quote:

Originally Posted by ving

something i learned at kindy was there is no right and wrong in join the dots, it just art

My kindy teacher used to give me a big smack when I got join the dots wrong.... but it hasn't hurt me in any way ... *twitch* *twitch*

yagon · #8 15-03-2006, 09:12 PM

this has been a source of considerable frustration for me

I've got 2 books on astronomy that show constellations and locations of DSOs. both show very different patterns (lines) for carina. i'll be damned if i pick make them match.

i've tried to find eta carina a half a dozen times, but i can never tell which cluster/DSO is the right one because of the inconsistent sources that i'm using.

my plan at this stage is to buy a definitive star atlas, if such a reference is available. any suggestions?

Vermin (Tom) · #9 15-03-2006, 10:45 PM

The lines are only asterisms, i.e. patterns you can use to star hop. It does not matter who's asterisms you use, the stars and DSOs are still in the same place!

Volans · #10 15-03-2006, 11:24 PM

If you are using a good star chart then you will not have to worry about different "join the dots" in different books. It all comes down to being able to read a star chart properly.

I use 2 charts; one chart gives me a basic outline and most importantly, the Greek Bayer letters of each star in the constellation and the second chart gives me a quite detailed map around those stars that have Bayer letters.

The whole point being, the Bayer letters allow me to correlate between the charts. I use the basic chart to observe the constellation with the naked eye and this means I have a pretty good idea as to where I should point the scope and in what direction I need to move it.

Once I centre the scope on a known star then I can look at the detailed chart and start to pick up simple star patterns nearby. I mean things like, an elongated triangle, a string of 4 stars in a slight curve, 2 stars VERY close together, things like that. This helps you define a direction when you are looking through the eyepiece.

An example:

You look through the scope and you see your main star and a square of stars just to the right. You check back to the chart and swivel the chart around to match what you are seeing in the scope. Now you can see that you need to go to the left...away from the square...to get to your object. So you gently nudge the scope so the view goes away from the square and then you check your chart again to match what you see through the scope to what you see on the chart.

In this way you will "star-hop" to your intended object.

Ignore the "join the dots" images when it comes to hunting down objects with your scope. Use the Greek Bayer letters to recognise stars and to move amongst them.

Remember, if your scope has digital setting circles, a computer, etc. then one night the unthinkable will happen....the electronics will go KAPUT!! If you have relied on the computer to show you things then you will have a perfectly functioning telescope ( in that you can still look through it) but you will not have a clue where to point it.

Learn how to read a star chart and then you will always be able to find those illusive but amazing deep sky objects.

Peter.

Blue Skies (Jacquie) · #11 16-03-2006, 01:08 AM

Quote:

Originally Posted by ThunderChild

This got me thinking : Has the Chandler just approximated constellation lines due to size constraints? Or are the shapes and make-ups of constellations not an exact science? Is there room for different opinions from source to source?

I had just made the assumtion that they were set in stone. Perhaps I was wrong there.

Only the constellation boundaries are set in stone (well, at least for the current Epoch). Whatever is inside them is open to interpretation. While there seems to be some consensus with most constellations some seem to have several patterns - I think it all comes down to whichever pattern the author likes at the time. I regularly see two versions of Gemini. I'd go with whichever one you like best, if it helps you remember it in the sky. Plus what Volans and Vermin said too, about DSO's.

Dave47tuc (David) · #12 16-03-2006, 06:58 PM

Just a quick point,
Don't learn the constellations, learn to find the bright stars first. When you can do that from season to season that will make it easier to find the constellations.

Try finding the 1st Mag or brighter stars first.
Good luck.

RAJAH235 · #13 16-03-2006, 07:56 PM

If you're finding objects by their 'shape', then I suggest that you do not buy a Herald Bobroff Astro Atlas. (if they were still in print). They don't use any kind of constellation/asterism markers, other than a few 'straight lines' between them!
A planisphere & my H.B is all I use.
ps. As already suggested, find the 'part of the sky' with your planisphere n rotate your charts to suit..star hop from there..