Sky Atlas

[steve_bham]

Strange question but can sky atlases go out of date?

Reason im asking ive got a Deluxe verison of the Wil Tirion Sky Atlas 2000.0.

Is it still useable?

PS. your welcome to tell me to shut up if its a silly question!

[kniclander]

good question! they do go out of date because of the "wobble" of the earth on its axis and the "relatively" large apparent movement of some nearby stars but the 2000 version should do you for the time being

[ashenlight]

Hi Steve,

No question is ever silly on SGL!

My instinct with this is that no, it will not go out of date... at least for the next million billion years... the stars are so far away that any movement that is experienced by them is so infinitesimal to us that it will not be noticed from our Earth bound location for a very, very long time yet. Over a given period of time, true binary stars will go around eachother, changing their positions in relation to their partner... but, for instance, Ursa Major will still be Ursa Major when, perhaps, humans are long gone!

I hope someone can give you a more concrete answer on this.

Amanda

[steve_bham]

Cool! so it wasnt such a silly question afterall! How long do they normally say current for?

[ashenlight]

Steve, did a search on the net for you and found this http://spaceplace.nasa.gov/en/kids/phonedrmarc/2002_september.shtml You might find it helpful, made things really clear for me anyway

"While the seasons affect the position of the Sun, they do not affect the orientation of the stars, since these are determined by the 'celestial sphere', an extension of the Earth's geography into space. However, the Earth is also subject to a long, slow 'wobble' of its axis - the direction of its tilt remains almost static in relation to the SUn over the course of the year, but it does move very slightly. If the direction at right angles to the Earth's orbit is considered as 'straight up', then the poles would describe a circle around it every 25,800 years. This wobble is called 'the precession of the equinoxes', and it causes the orientation of the stars to change, while, ironically, the fast-moving Sun maintains more or less the same path through the sky. As a result, the path of the Sun's motion through the sky changes against the background constellations over very long periods."

Taken from Giles Sparrow, The Stargazer's Handbook: An Atlas of the Night Sky, Quercus, p. 13.

Just to develop on kniclander's point hope you don't mind kniclander.

Amanda

[steve_bham]

Thanks for quick replies, at least its one item i dont have to buy, just got to learn how to use it now. Bit said really ive had it for all these years and not taken the time to understand the book!

[ashenlight]

No time like the present Steve be sure to ask if you've got any other questions

Amanda

[kniclander]

Just to develop on kniclander's point hope you don't mind kniclander.

Amanda

happy to be developed; makes a change from being corrected

[acey]

I have an old Norton that is "Epoch 1950", but "Epoch 2000" atlases became the norm well before 2000. I suppose "Epoch 2050" atlases will appear from around 2025, assuming anybody is still using paper ones by then. (Hope so!).

For most purposes the difference is so small that you wouldn't really notice it. But the NGC was ordered by right ascension in the 19th century, and since then precession has thrown things a bit out of kilter, so that the numerical order of the objects no longer matches their East-West order in the sky. Makes it a little harder for me to tick off objects in my copy of NGC.

[brianb]

good question! they do go out of date because of the "wobble" of the earth on its axis and the "relatively" large apparent movement of some nearby stars but the 2000 version should do you for the time being

It will be usable for about another 50 years. Precession will take its effect beyond that but the basic patterns will be good for millenia ... expect to start seeing atlases etc. with positions computed for epoch 2050 around 2030.

[themos]

A number of stars could blow up any minute (or rather, the light from the explosion culd reach earth any minute).

[ashenlight]

themos, I often think about that... wouldn't it be weird to suddenly look up and Ursa Major's saucepan handle is radically shortened! Or the Keystone is missing a corner!

[Deneb]

Strange question but can sky atlases go out of date?

Reason im asking ive got a Deluxe verison of the Wil Tirion Sky Atlas 2000.0.

Is it still useable?

PS. your welcome to tell me to shut up if its a silly question!

I have two of these Atlases, an extra one was sent by mistake, I was thinking about giving it away

[JamesK]

Betelguese... When that thing goes off we'll know about it! It'll be like having a full moon - ruining DSOs in the area for a significant period of time I would think... But if that doesn't generate intrest in astronomy, I don't know what will. Be a laugh if you were looking at it when it happened - through a scope it would hurt your eyes I would imagine! At any rate, the millenia old Orion would need some reconstructive surgery, owing to the fact his most impressive shoulder blew up. I'm now imagining a sort of constellation hospital, reminding me I should probably return to revision and stop imagining such far out things.

James.