How to use an astrolabe I Curator's Corner S3 Ep1

Curator William Greenwood talks us through the different parts of an astrolabe and how to use it.
To find out more read William's blog about astrolabes here: goo.gl/JGd75z
#CuratorsCorner #astronomy #astrology

[@iaincaillte3356]

How many nights and days of observation, how many calculations, how much metallurgical skill went in to making that device? When one holds an astrolab, one holds centuries in one's hand. Humility is the word.

[@teenieneenie630]

How very eloquently said.

[@MedicalParasitology]

Indeed..

[@chanammachattivaralakshmi5140]

So much of patience

[@Ryan-bb8lg]

Modern computers sometimes ruin the coolest historical gadgets.

[@sangramkale3243]

I wonder about the same things.

[@jerkfudgewater147]

All i learned was that that thing needs a longer video to explain

[@GRosa]

Try watching this one: kzbin.info/www/bejne/r4O3dJ6NrcylhsU

[@fabclark123]

@therealnightwriter and you should try to BE POLITE! jackass...

[@senate90]

@therealnightwriter well aren't you a big wonderful! Why not help instead of putting someone down?

[@1bobini]

Gabriel Rosa thanks for sharing the link, very good information on the astrolabe.

[@DownhillAllTheWay]

@@fabclark123 " jackass" - says he, politely!

[@Gh0stClown]

"Astrology is seen as somewhat less scientific" - understatement of the century, right there.

[@fabclark123]

Hey now, you don't know that. A babe born unto us in say July will have had vastly different seasonal exposures to January's child, producing character traits that astrology historically well accounted for. Said infant's dietary intake in those first crucial months will inevitably have been effected, limited, advanced who knows - different is all I'm saying. Same goes for the level of maternal attention bestowed upon said infant, owing predominantly to her increased feminine responsibilities during different months of the year - think preparing clothes for Winter, repairing nets during high flood season and so on and so on. In short and by way of conclusion, you need to check your privilege friend. Just because you weren't born in 8th Century Baghdad doesn't mean you should judge those who were! These traditions arose based on millenia of observation - non-sceintific I grant you but observatiion none the less. This goes for numerous curious events, within which I would include astronomy, ley-line reading, ghostly phenomena and of course Quantum Healing Hypnosis. I will take your non-response to this comment as deriving from the awe-struck moment of epiphany which my wisdom will surel have evinced in you - be bold, it will pass, and you will stride anew into this world, reborn with sight keener than before, a skeptic no more. And yes, you can thank me later friend. My very best wishes to you and all KZbin commentators.

[@danilonascimento9866]

egg54543543543 "I will take your non-response to this comment as deriving from the awe-struck moment of epiphany which my wisdom will surel have evinced in you" What a childish statement! You must be very egocentric to think that your wisdom is so much that you, just speaking, are always right and people are lucky and "enlightened" by your speech. Beyond that: I was born in a tropical region, and the difference between the seasons is almost imperceptible or nonexistent, like much of the Islamic world. In addition, the sky and the seasons are different in other regions of the world and the Islamic culture was spread in a great extension of the globe. Your argument assumes that the whole world lives in temperate regions and is basically like Europe. And it's almost racist assuming that all other cultures in the world have developed like the European. In short, it is YOU have to check your privileges and your vision of European white origin applied to others cultures.

[@fabclark123]

Danilo, your fury is correct; you are correct. The time is coming now for you people of the Third World, the Developing World to conquer us. Our hour is past; you grow strong, and we are but the great-great-grandchildren of once great men; we are nothing. Your time is coming, and Danilo, I beg of you this: when that time comes, have mercy upon us, as we once had no mercy upon you. I fear you, I fear you. Pity us, Danilo, Pity the once wise now weak western man. We descend into a civilisational alzheimers. Show us what it is to be alive again. We need you; come for us, redeem us. We need you again. Good luck, Friend.

[@stfclm]

Nurse, Egg has taken the wrong pills again!

[@fabclark123]

too much truth eh blueman? I know the feeling. Still you'll get used to it... The game is up, friend. Our day is done. It was a good run, this "western" civilisation, we had a time, a good time. Remember the '90s? Me too. Problem is, ever since communism fell, we've had nothing to prop us up inside, except the terrorists maybe, but they were never up to much. No, it's over, it's all over. We have nothing left to give. Capitalism?! Don't make me laugh! No, our only hope now lies in the immigrant's way, his dynamism, his earthy passion, his outrageous existence, is all that can touch us now, can break the rigor mortis grip of a culture consuming itself. Don't worry Bluey, it'll be ok, one day. Danilo, seize my lands!!

[@marksminis]

The astrolabe was the first widely available hand held computer / calculator. There were expensive, but brass ones were affordable by many. The first book written in modern English, by Chaucer, is a guide to using the astrolabe. I have one and figured out how to use it. It is about 4" in diameter and can tell time to within 15 min depending on season. If you can identify a star in the sky that is on one of the spurs, you can tell time at night even more accurately. I love mine it's a sweet little personal treasure. Bought it at a Renaissance Faire.

[@user-fr8jg8pv4d]

Is it a available online?

[@hermespsychopompos4615]

And the Antikythera Mechanism was the first analog computer. Greeks, man.

[@igramaramiceimakaze8327]

@@hermespsychopompos4615 Egyptians, Sumerians, Babylonians, Phoenicians, Persians and other Middle Easterners were far more advanced than your people. Middle Easterners are the cradle of civilization.

[@robkunkel8833]

a great observation tkx

[@91JLovesDisney]

Not sure I'd call it 'modern' English lol

[@ingeborg-anne]

At this point I've started imagining that every curator at the museum have a literal corner in which they spend their days :D

[@fabclark123]

They do!

[@kryw10]

I'm guessing you're very close to the truth.

[@timhyatt9185]

I have to wonder if their corners ever overlap and they hold after-hours contests to vie for supremacy... Would all be very formal of course....the challenger would issue the challenge, the defender chooses the means of the contest...

[@rikospostmodernlife]

That architecture must be non-euclidean

[@almareyes2192]

I would 😂😭🧡🧡

[@typograf62]

My father once made an astrolabe for his class (he was a teacher). It came in two versions, one handheld of plywood, paper, copper and acetate film - used handheld. The other solely made from acetate film was used on an overhead projector. I still have the plywood version.

[@anomalyp8584]

How do you make it?

[@staxenglish]

@@anomalyp8584 Witchcraft

[@Phlebas]

Sometimes I love this modern information era. I was reading an article about celestial navigation, astrolabes were briefly mentioned, and out of sheer curiosity, I asked Google how these instruments work. This video came up, which gave me a pretty good general idea. Now I've found a really good KZbin channel that I was previously unaware of. Subscribed! On another note, I'm a field archaeologist. I've done it for six years and I feel I have at least another six years in me, but curation interests me as a possible future career that's a little less physically demanding.

[@patstokes7040]

I was going to say you learn just about nothing from this video.

[@sheriffdraws8789]

Cool. I'm a designer and I was looking behind the scenes of the movie Eternals and what inspired their costume designs and I came across the astrolabe and this video popped up. You learn everyday lol

[@user-xy8es3rw4i]

unfortunately, it works only for english speakers (

[@ashy1423]

I have never been so engrossed in a video on you tube. Thank you. Ashraf from Scotland 🏴󠁧󠁢󠁳󠁣󠁴󠁿

[@adel-a]

The first astrolabes were mainly used for triangulation giving latitude and simple distances. Al Fazari 8th century, added angular scales. Al Battani, in his book Az-zij was the first to write the mathematics behind the now sophisticated device. They represent the most important stars in the celestial sphere. Alkhawarizmi made good use of it finding the angle of the ecliptic, the Earth's tilt on it's revolution around the sun. However, this astrolabe is quite small. A pocket version? It must have been useful and practical for travellers. Whatever the case during the Islamic civilisation, a whole new craft was invented to keep up with the demand on astrolabes around the Islamic world. Another interesting point is that women too were into this craft to make delicate and accurate astrolabes. These were delicate and beautiful pieces of art as well accurate and practical scientific tools.

[@audijohns9187]

Negative they were used to navigate with.

[@elkinmontoya9640]

@@audijohns9187 You must be thinking of the mariner's astrolabe

[@lindaj5492]

@@audijohns9187 Nowhere does he say they were NOT used for navigation. Latitude & distance are used for navigation.

[@aranhaydar9195]

@@elkinmontoya9640 he's right, you can. People in the middle east were/are although to a lesser degree in the last 50 years, knowing of the day vs the location of the moon. Knowing the day you'd know the location of each star, and with that you could very easily navigate your way through the nights. :)

[@aranhaydar9195]

@@lindaj5492 😁

[@johng.arkenberg1070]

I think it's wonderful to see how many videos there are now about the astrolabe and its use. My parents bought me a reconstruction when I was a teenager to better learn astronomy and I still use it. The diagram at 1:42 is misleading because the plate is not oriented properly so that it would give a correct reading. The close up of the astrolabe in the curator's hands at 3:04 has a correctly oriented plate. The dotted line they say is "directly above you" is the meridian and it should be pointing straight up towards the ring. The orientation of the plate is critical so that you can to read the correct time since the edge of the astrolabe reads out like a 24 hour clock face. When he says this "is directly above you" he was probably pointing at the zenith, which is the point in the middle of the concentric rings on the plate. As I said before, the dotted line is really the meridian which is the line from North to South that passes through the zenith. Also, the horizon is not a straight line on an astrolabe, but actually the curved line that bends under the pin in the center. If the plate was properly oriented the horizon would begin at around 6a.m. on the right side of the astrolabe's edge, curve under the central pin and end at 6p.m. on the left edge. In this illustration it goes from 8a.m. to 8p.m. I can understand some of the confusion about how it works since that is sort of glossed over. A simple attempt to explain is that you use the alidade to measure the height, or altitude, of the sun (or a star at night) above the horizon. The rete allows you to then position the sun or star on the plate at the same altitude you measured. If you use a rule to trace from the location of the sun or star through the pin to the edge you can read the time out at the edge as a 24 hour clock. More importantly, you can use it to calculate where the sun and stars will be throughout the year. However, and here is the big limitation, so long as you have the plate made for the latitude you are currently at. Still, a remarkable piece of technology!

[@kristenmoonrise]

This is so interesting. I'm learning both astrology and Arabic. Thanks for sharing!

[@IremGokoz]

A similar astrolabe is displayed at Pera Museum in Istanbul. It is fascinating to see how it actually works because it is not quite easy to guess how. Even though I watched it 4 years too late, thank you so much for this video.

[@devakadesilva5673]

Thanks for a wonderfully genuine explaination. Love it when people put aside their egos and try to bring out unbiased and factual information as much as possible. That last reflection on whether its clear, showed your intent. Thank you! Also, magnificent invention of our predecessors. Reminded me that we must never forget that we are all here today, in this supposed modern era, because of those who studied hard, progressed science, and invented things. Rather than receiving these things easily, for our conveniences, we must recognize the importance of our own development so that bring about advancement. But NOT at the cost to human values, ethics or biological development. Convenience is a silent killer of growth.

[@chicken_kiev9929]

I came across astrolabes while studying for GCSE and was wondering how they actually worked. This video answered all of my questions, thank you.

[@apcolleen]

This is by far the best explanation at how these are used. Thank you.

[@hurdygurdyguy1]

Really? This is the best?! 🤣 this might change your opinion... m.kzbin.info/www/bejne/qHykm6V5j9aqZq8

[@vuefineart]

Exquisite device and great lesson, thank you. We are looking forward to more episodes. Cheers to the pursuit of the cosmos!

[@clearcrystal319]

This is amazing. Thank you so much for this video. Now I want more from any civilization! Thank you for sharing!

[@SilverEye91]

Interesting. I've seen these devices but never knew how they worked.

[@fabclark123]

Do you think we care?

[@SilverEye91]

egg54543543543 What's your problem mate? A little angsty?

[@fabclark123]

sorry, various things have been getting me down lately. I apologise.

[@M_Faraday]

I still don't know how they work.

[@JingLiSH]

true. i need further lectures :))

[@littlejuicebox]

That's such a beautiful device, thank you for the in depth explanation and telling us what each part was called

[@SCBJQ]

Thank you for a very interesting video. I'd like to see more of William.

[@sail2byzantium]

Well, cool! More of this kind of ancient and medieval astronomy, please!

[@MelchorMoore]

Yeah. I liked his presentation too. The gloves and respect for the object. He makes me want to go do some research

[@sikeimmike]

His voice is so calming.

[@AndyCutright]

Yes, I like the way he speaks.

[@thomasjones8079]

Fascinating - thanks for your explanation.

[@Otokichi786]

Astrolabe: Holding the World, the Heavens, and the Underworld in your hand(s).

[@silentriddles4907]

You said it so beautifully both literally & figuratively about such device, I don't know why that touched me so much inside. Thank you for sharing such comment

[@Herr_Vorragender]

Wicked! I've seen one in a museum in Florence once. I had no clue what it was for never mind how it works. And now I'm mindblown. 🤯

[@breck112000]

Thank you, I had always wondered how an astrolabe works!

[@GungaLaGunga]

Amazing. Excellent presentation. Thank you!

[@JEEDUHCHRI]

I tend to take for granted that in the present we are surrounded by so many items that have been created with precision. Even down to the most mundane household items are still made with a machine level of quality and precision. Imagine being a peasant 1200 years ago. Most of your interaction with man made objects would mainly be with items made with care and attention but still rather rough (comparatively speaking). But it must’ve been so very rare to come in contact with something made with such attention to detail and top quality. An object which demanded the builder to be precise and unerring in many ways. Absolutely fascinating. Not to besmirch the craftsmanship of tools, clothing, homes, art, etc of those times way back. Just that a machine like object must’ve been very alien to most common folk.

[@pietersanders7761]

Thank you, William. That was very interesting and enlightening. I often wonder how much technology has been lost in the mists of time through simple ignorance. Your insight helps to prevent that.

[@artiste8491]

Thank you for sharing the video. I am very proud of the contributions of Arab Muslim scholars to the development of human civilization. These civilizational achievements and many others have been erased from history. thanks YOU brother.

[@Cal6009]

Beautiful and inventive.

[@faramund9865]

Pretty good, thank you!

[@moola9755]

unintentional asmr too love this thank you

[@ES-xx2jq]

This is amazing, could you please do more videos on scientific instruments?

[@ignaciovega8324]

I loved, great job. There is the possibility that you can recommend an article or thesis to study a little more in detail how the astrolabe is used.

[@overrooftops]

I heard Neil deGrasse Tyson mention this and had to check it out further. Your explanation was enlightening. Thanks so much for this video!

[@chriseddiechannel4729]

Same

[@staxenglish]

@@chriseddiechannel4729 Why would Neil Tyson the heavyweight champion of the world talk abouylt Astrolube?

[@eddiemperor]

I just visited the Planetarium in Chicago and saw one of these up close....I'm obsessed w this now. I want to learn everything about this!!!

[@JimimIsMyJamot7]

Definitely made sense. Thank you.

[@daninb8939]

This was incredible!!!!

[@darkcognitive]

Interesting device.

[@1HorseOpenSlay]

I would really really love to find out those thousand uses that were discovered. SO interesting!

[@mhk5272]

very interesting, i would like an extended video on how is works, may b 3 main readings that can be done.

[@anomalyp8584]

The craftsmanship is just breathtaking. Even for today's standards.

[@hassanahmed1755]

Totally agree Imagine those craftsmen made such devices living now a days, and saw Rolex watch, they would say hold my beer Rolex I can do better 😆 although Muslims don't drink

[@AlexandraRojasHerrera]

Thanks for the subtitles

[@crc.agoodguy]

Everyone can be a teacher. It is somewhat surprising that such a young man could be so well-educated. I am surprised that someone so young could teach me so much. This is a fascinating ancient device. He must have been educated buy some of the best educators possible or perhaps he is some kind of prodigy. I found this discussion of ancient devices to be fascinated.

[@deeneroaabrildeagostoadici2689]

it was interesting!!! coud you do more videos about it?

[@mhdkrpz]

Just a minor correction! In fact the arm at the back of the device is not العدادة as many might think, but it’s العضادة which is the true equivalent of “arm” in Arabic.

[@DavidMaurand]

it's rather like a smartgadget. amazing combination of artistry and engineering.

[@northernstarlite]

thank you. i need this.

[@WickedKingLycoan]

I’m interested in how this tool was used for possible surveying, as well as it’s accuracy In doing so.

[@matonmongo]

Great explanation of the ancient predecessor to celestial navigation, now replaced by GPS. Which 'Star' one was born under was actually a pretty big deal back then, and even more important than the 'Sun Sign' astrology we think of today. For example regardless if one 'believes' in such things or their particular political affiliation, it's interesting to note that the current POTUS was born under the fixed star Regulus, known as the Star of Kings and one of the four Royal Stars of Persia. It was also known as the “Heart of the Lion” (or Lion’s Heart, Cor Leonis in Italian).

[@classicat87]

This was so interesting! Does the Astronomical clock in Prague work in a similar way?

[@gagatube]

In the sense that both instruments use a stereographic projection of the celestial sphere on to a flat surface and have a Rete rotating above that - yes. But obviously you don't look through the Orloj in Prague and cannot use it for all the other functions an Astrolabe is capable of. Also the Orloj omits reference to the bright stars and concentrates solely on the Zodiac as a measure of ecliptic longitude and the movement of the Sun and Moon within it.

[@dominickcsoliz]

I actually own one and never understood it but thought it was a beautiful object now I’ll really love the one I have more

[@marthavillegas6250]

Thanks for your video.

[@existentialvoid]

I have an medieval Jewish astrolabe passed down in my family. Fun to learn to use.

[@Camaika1997]

He has such a calm voice °v°

[@KaiTakApproach]

Makes good sense to me but I have some background in amateur astronomy and flight navigation. Thank you...I thought that was well done.

[@voxnihili8278]

More of these instruments, please!!!!!

[@isshinryu11]

I purchased an astrolab recently. It appears to be of the same material your device is made of. Is it brass? The finish is discolored a bit. What do you use to clean the astrolabe? Should I attempt to even clean it?

[@afterbangable]

What an awesome video and explanation bro, thank you so much!!

[@stevecurran483]

This guy is one of the most interesting curators ive watched. Brilliant. I hope he makes much more videos.

[@pashabvr]

So interesting!

[@going2sleep]

Fascinating. I want one even though an app on my phone can do it.

[@kryw10]

That was fascinating. Is the Antikythera mechanism thought to be an astrolabe of sorts? It was funny to me when you said that Astrology was the study of what the sky does to us, because I've always thought of it as what the sky represents to us. Still not science, but interesting. I could watch this all day.

[@catladyfromky4142]

From what I know about the antikithera mechanism, it was for predicting eclipses and other future events in celestial phenomena.

[@1234OTAKUANIME]

That's so freaking cool!

[@2ndRatePetronius]

Very cool!

[@--Paws--]

I actually wanted to know what the heck these were, I keep seeing these in thematic shows and book illustrations. Recommendations finally got it right.

[@junedewar3551]

Hi William! As your expertise is the knowledge involved in astrolabe sciences and astronomy, I am wondering if you have in the British Museum an Astrolabe time piece that was sold at Bonham's in London on the 13th December 2011? The time-piece was one of three quadrants. The quadrant bought had the King's Stamp imprinted on the back. it was believed to be a Richard ll find. That Astrolabe clock was found in Australia where Catherine Stewart's husband was banished because she refused to marry into Prussian Royalty and married a local farmer's son instead. When John McIntyre was banished to Australia in 1853 as a prisoner, Catherine gave him valuable antiques so he could return to her at a later time. One of these items given was a Robert ll time piece with that Kings stamp engraved on it. I wonder if you know what kings had the three pieces and I do wonder if it is definitely clear it is Richard ll and not Robert ll. I wonder how clear that stamp is having the Kings endorsement.

[@wolfpackforge8474]

I would like to know which stars they would use. obviously the North Star is one of them but what are the other 4?

[@professorsogol5824]

If fact, maybe not Polaris. This reference say " key stars which are easily visible with the naked eye such as Rigel and Altair." muslimheritage.com/article/using-astrolabe Although neither Rigel nor Altair are in constellations on the Zodiac, I'm guessing bright stars on the Zodiac would be common. NB the site at the link has a great deal of additional information on how to use an astrolabe.

[@EllaShartiel]

Bright stars like Rigel and Sirius if I remember correctly

[@lynnblack6493]

I would never know time date or where I was... But I did learn so very much...

[@flamencoprof]

So... an expensive hi-tech miniaturized multi-purpose tool. What does that remind me of? (Not that I have one.)

[@ChasingMidnight001]

Who else wants to own one?

[@IHateThisHandleSystem]

Very much so

[@7ajhubbell]

Thank you.

[@p_heinel4726]

I am interested in this thing How this thing can calculate where in the world we are, like some kind GPS in nowadays

[@jackiec9062]

That was so interesting x

[@ZiauddinKhan303]

Thanks! I was time travelling and needed this. I tried Google maps offline but my phone disappears there.

[@annakeye]

Also the brand name of a very popular wine here in New Zealand, _Astrolabe_ they make the usual ho-hum _sauvignon blanc_ from Marlborough that housewives just rave about. I'm going to have to go to the winery and ask them about the name.

[@salonykumari9369]

Thank you 😊

[@TheElectricCheeseProductions22]

1:00 I think that's something of an understatement.

[@eddiehourani7160]

It makes sense! many thanks :)

[@adolfninh23]

love this

[@williamkuhns2387]

Could the planispheric astrolabe be used to navigate in the desert where there are no fixed geographic features?

[@butterbee_bb]

This was very cool. And yes, it made sense :)

[@obnoxiouspriest]

I bought an astrolabe in Morocco some years ago and gave it to my father. I'll have to send him this video and maybe he can make some use out of it.

[@adolfotapiagallardo]

este video tiene serias deficiencias y prejuicios ... te recomiendo el siguiente: kzbin.info/www/bejne/sIq0n4ltrbebodE

[@NiniHallow]

@@adolfotapiagallardo Buen día Sr Tapia, he notado que responde en español aunque los comentarios estén en inglés y me preguntaba porque no ha decidido responder en el mismo idioma de quien pregunta. Sé que no es asunto mío pero se me ocurre que quizá ellos no entiendan español y a lo mejor piensen que sus aportaciones son spam o algo así.

[@adolfotapiagallardo]

@@NiniHallow amix! estoy en un ordenador portátil (laptop) con google chrome que tiene una extensión de traducción y que funciona muy fácil: se hace click derecho con el mouse y se escoge traducir al español! en este caso traduce TODOS los comentarios! estén en el idioma en que estén! claro que si estoy en el celular, NO sabria que hacer le agradezco mucho su comunicación! muy reconocido! además, ya me convencí de que el astrolabio FUE muy útil en su época! actualmente puede usted visitar este buscador virtual de objetos estelares! se lo recomiendo es magnífico!! www.worldwidetelescope.org/webclient/ y si está en celular, use la app SkEye saludos desde el perú!

[@All4Grogg]

Note: they have to calibrated to the latitude where they are used to work accurately. The ancient people who developed them knew this... Because they knew the Earth was NOT flat 😉

[@audijohns9187]

@@All4Grogg exactly, I see many try to say they are off and incorrect.

[@Charles-ze6ge]

I know this is 5 years old but Very interesting, Thanks!

[@kelliethornton7986]

At the beginning, he introduced himself and his job and I jokingly thought "British Museum curator, telling us you're a thief right outta the gate huh?" and had a little laugh to myself. Then he followed his introduction with highlights of historical artifacts from an exhibit from a completely different country and culture. Damn you, John Oliver!

[@hawaiiankingdom4186]

Greetings, Aloha to All! Awesome content

[@zakrider5455]

I learned all that the stuff that i wasn't heard in my Life

[@thebatt6183]

fascinating

[@TheWereparadox]

I've looked at the sun and am not blind. XD Thank you for the information. Very complex and valuable instrument.

[@TheWereparadox]

@Mycel Neet. The sun is so bright without it you can only look at it for a few seconds before it hurts too much. I've also noticed the difference between looking at the sun through a darkened window or not. (I'm not actually fool hardy enough to try and have a staring contest with it or anything tho. More like to see if I could)

[@TheWereparadox]

@Mycel XD That would be presumptuous of me to say that you are a well organized person in your daily life I guess. Love the President of the United States or not he certainly does things his own way. XD

[@chasecain3567]

That’s wonderful

[@gavintoohey6604]

This is so cool

[@robertotorino8862]

Does it still work? Very clever

[@whiskeyvictor5703]

Is there a modern manufacturer of a reasonably workable, accurate fac-simile of an astrolabe?

[@muznahkm5439]

Thank you

[@user-mp8mu5fe4f]

I searched for a long time, trying to find the measurements for the astrolabe, but I could not find them. Can you give me some information?

[@nameless6774]

mm so blessed u are to be allowed to “play” learn with it...can one have a model / replica that works as the original?

[@brich57ful]

Google "The Venerable Astrolabe".

[@andrew_owens7680]

Unless I missed it, you neglected an important point, this is all about latitude. So they were good at reckoning how far North or South they were.

[@Randomeaninglessword]

He mentioned that when discussing the interchangeable disks.

[@adamjbond]

Made sense to me.

[@RinpochesRose]

‘Astronomy was there to serve Astrology …’. I like that 🌝