Talk:Astrolabe

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Applications

It lists that there are around 1000 applications, what are some of the more common ones that were heavily used? How was the astrolabe able to do it? Krjwvq (talk) 18:00, 19 February 2021 (UTC)

The name

What is the origin of the name "astrolabe"? Is it in anyway related to "astro", stars, or is this just a coincidence? Nyh 10:53, 16 June 2007 (UTC)

American Heritage Dictionary says: Middle English astrelabie, from Old French astrelabe, from Medieval Latin astrolabium, from Greek astrolabon, planisphere : astro-, astro- + lambanein, lab-, to take. — Sam 13:05, 16 June 2007 (UTC)

OBS:coincidence may be correct but may not be the reason for establishing the origin of the instrument only with reference to the name. There are many monemnet preserved in present-day Iran and Indean Which begged only on function, to study stars.

In addition, the Persian language IndoEuropean ice, which means many of the words may be found in most european languages

20100609

As you know the oldest Astrolabe funded from the area once called the Persian Empire. With Arabs take over the Persian language had to suffer through a forced change. E.g. many Al-have been added in front of many names. Many words change shape because there is not enough letters in the Arabic language. In Arabic there is no letter P, every single word they come by change it either to F or B, In Arabic is not possible to say two consecutive consonants. Star pronounced therefore Estar or Astar and loop (loop= Circle, Circulate, means movement of stars) pronounced lobe.

Arzachel

I noticed that there was no mention of Arzachel, who perfected the astrolabe during the 11th century. There are two links verifying it on his page, and I also read about this from another source. Would it be alright to add a sentence or two about him on this page, in the appropriate setting (Medieval section)?

So, how is it possible that Greeks named an instrument that has been invented in Persian? Could it not be possible that Greeks who have been in contact with Persian have had to borrow the word? We know it's very common to borrow word, especially Loan from ruler’s language.

If I can prove that, I can prove even that the culture in a row with many other things that today are defined as Arabic is actually and originally is Persian. For instants KEMIA, this means rare in Indo-European language. But put a AL in front of it make it the known name AL-chime and its Arabic now. Why am I doing this? I think the right should be right. —Preceding unsigned comment added by 188.121.68.1 (talk) 08:52, 27 January 2010 (UTC)

Astrolabe

I wanted to confirm that astrolabes were once used to locate Makkah (Mecca) and I had to do a separate search to accomplish this. I think it might be helpful to add a link from the Astrolabe page to the Makkah page. Perhaps more precisely, it would link to the Qibla article, which does have a link to the Astrolabe article. I also noticed that there seems to be a discrepency in the spelling of qibah. ~~Donna, 15 June 2005

You are very welcome to include this information in the article itself. Sounds very interesting, sort of remiding of the way that the Chinese used compass for religious purpose as well. Thank you ! Rama 08:21, 16 Jun 2005 (UTC)

Does the astrolabe help locate a precise position or just the latitude of the observer? It's my understanding that it does not give longitude of the observer, and I believe this should be stated in the article, and a reference to the longitude article included. Also, perhaps a brief discussion of the fact that two coordinates are needed to locate one's position on the surface of the earth, and that knowing one's latitude alone is not sufficient to know one's location. Thank you! Dmp717200 (talk) 16:21, 21 October 2009 (UTC)dmp717200

I have a few questions that I am curious about. 1.) Why was there not any mention of the Arabic myth about the creation of the astrolabe? 2.) Why is there little information about the Ancient Times of the astrolabe? Is it because the information can contradict itself or is there no reliable source fo the given information? Jmk5mc (talk) 17:14, 16 February 2018 (UTC)

Invention of metal astrolabe

I'm not convinced metal astrolabes were unknown before the 15th century. I was struck in the museum of history of science in Oxford by a beautiful example from around 950, somewhere in the Islamic world. However, I don't have the details to hand... if I can find them, I'll make the change. UncleKensson 21:53, 9 October 2005 (UTC) UncleKensson

Yes, the SOAS website has the oldest known dated brass astrolabe, some 500 years before Zacuto's. I'll change the text accordingly. UncleKensson 22:29, 9 October 2005 (UTC)UncleKensson

The link to SOAS's astrolabe is now broken. A quick search did not reveal a replacement link. --Lboges (talk) 20:17, 29 August 2012 (UTC)

I found an astrolabe from their site, but its picture caption says: "Astrolabe, by Muhammad Muqim al-Yazdi, Persian, 1647/8--"

Is this different, or the same? At least this is not that old as claimed by user UncleKensson. 85.76.49.68 (talk) 02:49, 16 July 2020 (UTC)

I found this page very interesting but hard to understand, you should make it clearer I still don't understand how an astrolabe works! ~ Summer Eldemire Jamaica

Kilroy

I was here! I'm going to fix these faulty references, unless someone else is faster. Said: Rursus 05:34, 23 April 2007 (UTC)

Did some, more needed – the loose unnumbered references in References should be associated with a certain text position, when possible, and then moved there, to become surrounded by <ref>...blarefbla...</ref>. Said: Rursus 05:42, 23 April 2007 (UTC)

Astrolabe vs sextant.

I question the accuracy of the second sentence of this article. The astrolabe was certainly an instrument that was well known and fairly well used in many parts of the old world and the orient (in the original sense), but it has never seemed to me to be a legitimate navigational instrument at sea. The Mariner's Astrolabe was developed in the late 15th c., but that is not the same as an astrolabe. It is a round, open-framed brass instrument with an alidade but lacking the planisphere and other components. The mariner's astrolabe was little used, though - only a few dozen are extant in collections today (G.L'E. Turner Antique Scientific Instruments. also see last paragraph here). The main instrument of navigation appears to be (from 1595) the John Davis (English explorer)'s Davis Quadrant, aka Backstaff - it was more accurate than the mariner's astrolabe and easier to use, especially for observations of the sun. The octant and later sextant replaced the Davis quadrant as far as I am aware.

The compass has an old history, dating in Europe to at least the 13th century. This time frame make the first statement a bit awkward.

It seems to me that a separate page for the mariner's astrolabe is required to eliminate some of the confusion.

Michael Daly 17:44, 21 August 2007 (UTC)

I've added an article on the mariner's astrolabe. I've changed this document to reflect the differences in the two instruments. Michael Daly 02:27, 27 August 2007 (UTC)

Mobile Astrolabe and Horologium

I have added a link to Mobile Astrolabe and Horologium. This link enables mobile and instant access to the astrolabe or horologium model of the universe from any point of earth with update each minute. Also the postions of planets and stars are given. It also explains on the background and ingenuity of these monumental models of the universe. chrsyl — Preceding unsigned comment added by Chrsyl (talk • contribs) 15:58, 26 March 2011 (UTC)

Computer generated astrolabe, ecliptic longitudes?

The computer generated astrolabe is otherwise very fine, and I am glad someone bothered to make it, but I think the markings of the zodiac (near the ecliptic) are a little bit ... well ... wrong.

Signs of zodiac are (at least in astrology) defined using _ecliptic_ longitudes, not rectascensions of the equator. Therefore the center of the signs of zodiac is the pole of the _ecliptic_, not the pole of the equator.

There are signs of zodiac on the computer generated astrolabe. And there are also coordinates. Fine. There is something wrong however. The lines separating the signs and the lines showing the coordinates obviously point to the celestial pole, that is the pole of the equator, the center of astrolabe. Methinks they should not.

Of course you can connect the pole of the equator to the ecliptic and separate arcs of 30 degrees ... but I don't thing they are either _ecliptic_ longitudes or the true borders of the signs of zodiac (of astrology).

Because of stereographic projection the pole of ecliptic is not at the center of the projected ecliptic, but it surely is away from the pole of the equator which is at the center.

Have I totally misunderstood what signs of zodiac are? Is there a different astronomical definition for them? Maybe so, but I find this construction "rectascension of the ecliptic plane" rather unusual on an astrolabe.

My source? Hmmm ... common sense ... basics of spherical astronomy found on just about any work worth reading

Sincerely Vesa.V.Petäys — Preceding unsigned comment added by 212.146.45.78 (talk) 10:14, 24 January 2012 (UTC)

Yes I think you are right, there is a section in Van Cleempoel, Astrolabes at Greenwich (OUP 2005) which describes in detail how this error of laying out the ecliptic arises. Aparrently this is also an error found on some genuine antique astrolabes as well. Simonchadwick1023 (talk) 21:09, 8 November 2013 (UTC)

Astrolobes?

I seem to remember having once read about an astrolobe, and a search for it redirects here. Is that just an alternate spelling, and if so, shouldn't the article mention that? — Preceding unsigned comment added by 97.124.76.97 (talk) 03:46, 14 August 2012 (UTC)

• I think so! Aarghdvaark (talk) 00:34, 4 March 2016 (UTC)

re woking

I can find no citation any where for wooden astrolabes. this source is a really good one Lewis, M. J. T. (2001-04-23). Surveying Instruments of Greece and Rome. Cambridge University Press. ISBN 9780521792974. Retrieved 30 August 2012. and I plan to use it to improve the article. If some one else gets here first be bold J8079s (talk) 20:09, 30 August 2012 (UTC)

File:Iranian Astrolabe 14.jpg to appear as POTD

Hello! This is a note to let the editors of this article know that File:Iranian Astrolabe 14.jpg will be appearing as picture of the day on November 25, 2014. You can view and edit the POTD blurb at Template:POTD/2014-11-25. If this article needs any attention or maintenance, it would be preferable if that could be done before its appearance on the Main Page. Thanks! — Crisco 1492 (talk) 00:58, 4 November 2014 (UTC)

Picture of the day

An Iranian astrolabe, handmade from brass by Jacopo Koushan in 2013. Astrolabes are elaborate inclinometers used by astronomers, navigators, and astrologers from classical antiquity, through the Islamic Golden Age and European Middle Ages, until the Renaissance. These could be used for a variety of purposes, including predicting the positions of the Sun, Moon, planets, and stars; determining local time given local latitude; surveying; triangulation; calculating the qibla; and finding the times for salat.Photograph: Masoud Safarniya

Inclinometer?

I am surprized to see the astrolabe described as an "elaborate inclinometer". This is a description which I have never seen used in the extensive literature on astrolabes. Are all astronomical instruments (cross staffs, octants, sextants, quadrants, etc.) which measure the altitude of a celestial body to be classified as a type of inclinometer? AstroLynx (talk) 15:08, 3 January 2015 (UTC)

Image addition proposal

Animation showing how celestial and geographic coordinates are mapped on an astrolabe's tympan through a stereographic projection. Hypothetical tympan (40 degrees North Latitude) of a 16th century Europenan planispheric astrolabe.

Hello everybody. I find the astrolabe to be an amazing instrument, but also rather complex to understand for somebody that, like me, hasn't a good enough background in astronomy. I thought that a representation of what's behind the drawings on the tympan could make the 'Construction' section a little clearer. The tympan in the animation refers to a 40 degrees North Latitude and the elements drawn on it are the ones that were usually present on a 16th century European planispheric astrolabe. What do you think? I'll be happy to improve the gif if you have any suggestion. Thank you. Italianmitch (talk) 22:46, 24 November 2015 (UTC)

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Planisphere vs. Astrolabe

Both this article and Planisphere state that the astrolabe is the predecessor of the astrolabe. A brief comparison shows that an astrolabe can serve as a planisphere, but not the other way around - surely the articles should describe the planisphere as a modern simplification of an astrolabe? Stub Mandrel (talk) 09:19, 24 October 2016 (UTC)

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Cheers.—InternetArchiveBot (Report bug) 17:32, 4 June 2017 (UTC) hi. style="color:green;font-family:Rockwell">(Report bug) 17:32, 4 June 2017 (UTC) — Preceding unsigned comment added by 97.116.72.139 (talk)

The second image is missing accompanying text. Dutchy45 (talk) 22:40, 17 January 2018 (UTC)

oldest surviving?

I found a BBC article "Astrolabe: Shipwreck find 'earliest navigation tool'", which claims oldest surviving is from Vasco da Gama's shipwreck, manufactured around 1495-1500.
The article has a picture of an astrolabe from 1282, and a globe from 1144. The 1282 astrolabe is about 200 years older than the 'earliest navigation tool' claimed by BBC (or should I say BBS?). Is the globe also a navigation tool? Seems too big, but that would be 350 years older. 85.76.49.68 (talk) 02:54, 16 July 2020 (UTC)

Schematic Image Addition

In the construction section, I think it would be helpful for readers if a schematic of some sort was included. Any picture that breaks down the individual pieces of an astrolabe and labels them appropriately should do. Does anyone else agree or have a photo in mind? COeditor1 (talk) 16:48, 25 September 2020 (UTC)

References (for University of Edinburgh course Stars, Robots & Talismans)

Bibliography for National Museum of Scotland al-Saffar astrolabe Hernández Pérez, Azucena, Catalogo razonado de los astrolabios de la Espana medieval, Madrid 2018, pp 43-49.

Hernández Pérez, Azucena, Astrolabios en al-Andalus y los reinos medievales hispanos, Madrid 2018, p 96.

Jones, Jean and Uhl, Mary (eds.), Under One Roof, Edinburgh, 1996.

King, D. A., ‘Some Medieval Astronomical Instruments and their Secrets’, in Mazzolini, R. G. (ed.), Non-Verbal Communication in Science prior to 1900, Florence 1993, pp.29–52.

King, David A. 'Medieval Astronomical Instruments: A Catalogue in Preparation' in Bulletin of the Scientific Instrument Society No 31 (1991), pp 3-7.

Macdonald, A. and Morrison-Low, A.D., A Heavenly Library: Treasures from the Royal Observatory's Crawford Collection, Edinburgh, Royal Observatory and NMS, 1994, p. 24.

Maddison, F., and Turner, A., Science and Technology in Islam, exhibition catalogue, London 1976, pp.104–6.

Plenderleith, R. W., ‘Discovery of an Old Astrolabe’ in The Scottish Geographical Magazine, Vol. 76, No. 1, 1960: 25.

Phillips, P., The Collectors’ Encyclopeadia of Antiques, London 1973, p.604, fig. a.

Glairedanderson (talk) 20:42, 8 October 2020 (UTC)

Dubious claim an armillary sphere is an astrolabe

I was surprised that what is seemingly-obviously an armillary sphere, or at least obviously a sphere, was labeled as an astrolabe. It's a depiction of a sphere. It's not a flat disk. I don't see any pointers for stars like an astrolabe has. Don't see a rete or alidade. Not sure how it could be an astrolabe. I tried to look at the source for the claim, but it's a book I don't own in a language I don't read.

I did a quick search and grabbed the first 2 journal objects that discuss it, both call it an armillary sphere. One even includes it as a figure along with their tracing: https://www.mdpi.com/arts/arts-08-00062/article_deploy/html/images/arts-08-00062-g005-550.jpg

When I searched for sources that claim it's an astrolabe, I found one -- this wiki. Skintigh (talk) 23:19, 30 August 2023 (UTC)

My understanding is that the word "astrolabe" did not originally refer to the planar version, but to something more like an armillary sphere. This predictably causes some confusion. Cf. Armillary sphere § Hellenistic world and ancient Rome. Sometimes people specify that they mean a "planispheric astrolabe" or the like. –jacobolus (t) 23:27, 30 August 2023 (UTC)

Ha, I was just editing my comment to say almost the same and got a collision.

I wondered if it was a mistranslation from German from Greek?

I also note the image filename is "astrolabium" not "astrolabe." Ptolemy called the armillary sphere "astrolabon" and I swear I saw them called "astrolabium" somewhere... Skintigh (talk) 23:35, 30 August 2023 (UTC)

From what I can tell those are all synonyms caused by non-uniform translation/transliteration. –jacobolus (t) 23:43, 30 August 2023 (UTC)

I can't speak for the time of Ptolemy, but they are absolutely not synonyms anymore. Not for the last... I dunno, between 500 years and 1,800 years.

And "Astrolabium" may never have been a synonym. I did some searching and found: an astronomical compendium, a book named Astrolabium from 1575, some clocks named that, and a wristwatch, but no astrolabes nor spheres called that.

Closest I found was this mangled description: "Astronomical Compendium or Astrolabium (Astrolabe)"

https://www.toledomuseum.org/art/provenance-and-repatriation/astronomical-compendium-or-astrolabium-astrolabe

They have a picture of an object that seems to clearly be not an astrolabe, but is definitely an astronomical compendium. But perhaps it has astrolabe features as well that I can't see?

The only source that implies Astrolabium was the name of an astrolabe is this wiki, in 2 places:

1) a mislabeled/confusingly labeled photo which displays an astrolabe but names the book instead of the image. I clarified it.

2) This image (that may not belong in this wiki): File:Het gebruik van het astrolabium door Amerigo Vespucci, Jan Collaert II, Museum Plantin-Moretus, PK.OPB.0186.018.jpg

Is the orphaned word "Astrolabivm" related to the contents of the image? Or is it the title of the source book? Just an artistic name for the image? Does it mean "navigation" or "star gazing?"

Either way, it seems the image does NOT depict an astrolabe. There is what appears to be an armillary sphere on the table, and another armillary sphere in his hand. However, he's holding the armillary sphere the way one would hold an astrolabe... but looking over the top of the sphere rendering it completely useless. Maybe he's just doing arm workouts?

I wondered if it was this a spherical astrolabe, but the few photos I found of those showed a solid sphere, would be tough to look through that. But I guess if he's looking over the top it doesn't matter what he's holding. Could be a coconut or soccer ball.

I suspect this is just a confused artist drawing the wrong tool held the wrong way with the wrong label. It may even be based more on Dante's Purgatorio than reality.

Maybe this bizarre and (at best) misleading image shouldn't be in the wiki.

Same for the Mosaic.

They aren't even the right shape... Skintigh (talk) 04:53, 31 August 2023 (UTC)

Most of the sources containing "astrolabium" at the internet archive (~8500 sources in total) seem to be written in German or Dutch. A bunch are from the 20th century. From what I can tell they use it to mean "astrolabe". –jacobolus (t) 05:29, 31 August 2023 (UTC)

“They have a picture of an object that seems to clearly be not an astrolabe, but is definitely an astronomical compendium. But perhaps it has astrolabe features as well that I can't see?”

Actually, it does look to me like an (octagonal rather than circular) astrolabe. There is what looks like a gnomon standing upright in the center of the plate, and the darker-colored Rorschach blob spread over it could well be a rete denoting star positions. As for “compendium,” that might refer to the instrument hanging (pendere) from a chain or cord when in use. I’m pretty sure that object is an astrolabe.

Dodiad (talk) 06:59, 31 August 2023 (UTC)

Are we looking at the same picture? Where do you see an octagon? I see what appears, to my eye, an inkwell with a quill in it, sitting towards the rear of the table. Is that what you're looking at? I was referring to what looks to me like a sphere in his hand and another at the front left side of the table.

[edit, wait, were we talking about the mosaic? Sorry, it's been a while...]

Anyway, I think I found an answer!!!!!!! From a note in a translation of the Almagest Book V On the construction of an 'astrolabe' instrument:

In modern terms, it is an ‘armillary sphere’. The adjective ‘astrolabe’ applied to it and to its parts simply means for taking the [the position of] the stars’, and has nothing to do with the instrument to which the name ‘astrolabe’ is now usually applied (on which see HAMA II 868-79). The latter was called the ‘small astrolabe’ by Theon of Alexandria; see Rome[l ] I 4 n.O; by Ptolemy it was apparently called ‘horoscopic instrument’ (see HAMA II 866)."

An adjective! How's that for a twist?

So the armillary sphere was never called an "astrolabe," (the noun) by Ptolemy. At least per this source.

And the adjective can be correctly applied to an armillary sphere, to an "astrolabe" (the noun), and many other instruments which could explain the term popping up elsewhere (and the later confusion). Including in the above picture, where he is certainly taking the position of stars. Skintigh (talk) 20:23, 14 October 2023 (UTC)

According to Neugebauer, the works on the Astrolabe by John Philoponus and Severus Sebokht are both derivative of a work by Theon of Alexandria. Later al-Yaʿqūbī credited Ptolemy for more or less the same work (al-Yaʿqūbī only gives a table of contents for the first 2 (of 4) parts, including the section about the plane astrolabe, but his table of contents is nearly identical to the organization used by Sebokht, suggesting both were working from a common source), but it seems likely that he was substituting the name of Ptolemy for Theon.

Apparently Ptolemy's Almagest and also Proclus's Hypothyposis consistently used the name "astrolabe" to mean armillary sphere, but Theon used the name "little astrolabe" to refer to the plane astrolabe. Medieval sources started using just "astrolabe" to mean the plane astrolabe. –jacobolus (t) 04:48, 31 August 2023 (UTC)

No sure if you get notified of my other reply, but I think I found the answer and posted it above.

Long story short: "astrolabe" was an adjective in Ptolemy's time, and he used it as such, he never called the armillary sphere that name as a noun.

It became a noun in Theon's time. Skintigh (talk) 20:43, 14 October 2023 (UTC)

@Skintigh, jacobolus, Dodiad: So what is the conclusion here? I’m having a bit of trouble following the argument.

The point at issue seems to be the claim that the Casa Leda mosaic is the earliest known depiction of an astrolabe. As the claim is unverifiable to me (the nearest copy of the source book being over 200 miles away and in a foreign language; does anybody know what it actually says?) and as the sources in the image caption are unequivocal that it is in fact an armillary sphere, I can’t really see any justification in keeping either the statement or the image here. Is anybody here arguing that they should stay?
If there are no objections I propose to remove them from the article. Thoughts? Moonraker12 (talk) 22:32, 24 September 2023 (UTC)

I think the article's Etymology/History sections need to do a better job describing the early meanings of the word "astrolabe", but I don't feel like I know the subject well enough to write it. I've been slowly working my way through sources about Ancient Greek astronomy/mathematics, but am by no means any kind of expert. –jacobolus (t) 23:17, 24 September 2023 (UTC)

@ jacobolus: Well, I don't disagree about the etymology; but do you think the statement and image in question should stay, or are you OK with me deleting them? Moonraker12 (talk) 16:38, 29 September 2023 (UTC)

I think it's worth discussing and linking some kind of picture of an armillary sphere at the beginning of the history section. This mosaic happens to be one of the older extant depictions of an armillary sphere, but we could also use a photograph of a later 3d artifact. –jacobolus (t) 16:40, 29 September 2023 (UTC)

I don't believe our current text is supportable as a simple statement of fact: An early astrolabe was invented in the Hellenistic civilization by Apollonius of Perga between 220 and 150 BC, often attributed to Hipparchus. The astrolabe was a marriage of the planisphere and dioptra, effectively an analog calculator capable of working out several different kinds of problems in astronomy. But I want to do a bit more research in the literature to figure out what the best modern scholarship has to say about this question. We should sort out and clearly label which parts have direct evidence vs. which parts are speculative.

Armillary sphere § Hellenistic world and ancient Rome credits Eratosthenes with the armillary sphere (originally called an "astrolabe") but there were surely earlier examples of solid globes used for explaining astronomical phenomena, if not armillary spheres per se. –jacobolus (t) 16:49, 29 September 2023 (UTC)

@ jacobolus: OK, but this page is about the astrolabe, specifically the planar astrolabe, so having an image of an armillary on it just confusing... Whatever the history of the word might be. And I don't disagree with you about the 'current text as a simple statement of fact' but I don't see what bearing it has on the question at hand. Pictures here should be of astrolabes (ie. what we currently understand to be astrolabes); pictures of armillaries belong on the armillary sphere page. Moonraker12 (talk) 17:03, 29 September 2023 (UTC)

My point is that the planar astrolabe didn't emerge in a vacuum: it was an evolutionary step in a tradition of Greek representations of the celestial sphere on a solid/armillary sphere, and related spherical-geometry/-astronomy problem solving methods like the analemma (which we don't currently have an article describing). There are a bunch of extant examples of pictures showing astronomers/geometers/philosophers standing around pointing at spheres which indicate that this was a standard method of astronomical education/research.

Theon of Alexandria's (4th century AD) term "little astrolabe" meaning planar astrolabe evolved out of the word "astrolabe" meaning armillary sphere in Ptolemy's day. It's not clear to me what the planispheric astrolabe was called in the 2nd century, but according to Neugebauer Ptolemy mentions it in his book Planisphere as a "horoscopic instrument". So far as I know we don't have any earlier direct evidence, but some scholars speculatively give credit for the stereographic projection or even the planispheric astrolabe as a device to Hipparchus, Apollonius (on the basis that Conics contains a theorem relevant to the stereographic projection), Archimedes, or even Eudoxus.

I think this article should describe (briefly) that the spherical astronomy model on which the planispheric astrolabe is based developed in Greece in the 5th–4th century BC, that astronomers/geometers used solid spheres and later armillary spheres as a physical representation, that the stereographic projection was probably known sometime before Ptolemy but we don't have precise evidence about it, that at Ptolemy's time the word astrolabe was used to mean armillary sphere but that the planispheric astrolabe existed in some form as a physical device by then, that Theon of Alexandria called the planispheric astrolabe the "little astrolabe", and that eventually the name "astrolabe" came to refer predominantly to the planispheric astrolabe with the armillary sphere getting called something else. I think it's worth including a (clearly labeled) picture of an armillary sphere in that discussion. –jacobolus (t) 17:33, 29 September 2023 (UTC)

OK, thanks for explaining:

I can appreciate that the term astrolobos could well cover a whole family of scientific /astronomical instruments (armillaries, planar astrolabes; Celestial globes? Orreries? ) But if so that would be better dealt with in a dedicated article on the astrolobos, covering the early development of it (or them), and their diversification into the instruments we know today.

As this article is focussed on the planar astrolabe (which is currently what the word refers to), tacking on the sort of broad description you seem to be suggesting would be confusing (IMO): It should be enough here to say that the planar astrolabe (as currently known) is descended from the astrolobolos (whatever that might be).

The history of the instrument isn’t something I know a lot about; I mainly came here to find out what an astrolabe actually did (having found a book saying it was an early timepiece! I thought it was a navigation aid!) Moonraker12 (talk) 19:50, 30 September 2023 (UTC)

This article does not need to go into an extensive history, but only put the planar astrolabe in 1–2 paragraphs of context and explain that the name astrolabe formerly meant armillary sphere. –jacobolus (t) 20:21, 30 September 2023 (UTC)

Agree with jacobolus. Dodiad (talk) 21:09, 30 September 2023 (UTC)

Hang on: a minute: It’s one thing to say that the astrolobos (whatever that might have been) was the precursor of the planar astrolabe and the armilla; it’s quite another to say that 'astrolabe' is an old word for an armillary sphere. Where is the evidence for that?

For one thing the astrobolos was an instrument for making observations through, while an armillary is a device for making calculations (viz. here)

For another this assumption ignores the spherical astrolabe (which confusingly refers to two quite different articles; the later is this thing, which has a spherical rete and a ball-shaped tympanum) the earlier might well have looked something like one of these things.

So no, I don’t think you can say that… Moonraker12 (talk) 23:04, 1 October 2023 (UTC)

Ptolemy only ever uses the name "astrolabe" to refer to an armillary sphere (described in Almagest 5.1). Apparently Proclus also uses the same name in his commentary.

From what I understand, we don't have mention of other meanings for "astrolabe" until the time of Theon of Alexandria. Disclaimer: I am not an expert on this topic. –jacobolus (t) 23:32, 1 October 2023 (UTC)

The description of this armillary sphere can be found on page 217ff. in Toomer's translation here. Ptolemy's Planisphere mentions the planispherical astrolabe as a device, but just calls it a "horological instrument" and doesn't give it any specific name. For more about this instrument, Toomer recommends Rome (1927) (in French). –jacobolus (t) 23:39, 1 October 2023 (UTC)

Ptolemy never used it as a name for the armillary sphere. It seems the word wasn't a noun then, it was an adjective, and described any tool or component used for "star taking."

2 centuries later it was used as a noun for what we still call an astrolabe. I posted a little more detail above with a source. Skintigh (talk) 20:49, 14 October 2023 (UTC)

PS: I've been wondering if some of the confusion this has engendered is because the word still means different things to different people (The source for the statement in question is a book in German; does the word in German cover armillaries as well as planar astrolabes?). Just a thought... Moonraker12 (talk) 19:52, 30 September 2023 (UTC)

@ Skintigh, Dodiad: So, are there any objections to my removing the offending statement and image? If not I will go ahead over the weekend. Moonraker12 (talk) 16:40, 29 September 2023 (UTC)