Tom Wujec - Anatomy of the Astrolabe

Tom Wujec explains exactly what the function of the astrolabe is and how it can be used to tell time, direction and various star constellations.

[@stonebrother3751]

4:13 this is first "English" manual , not the first manual . There first description was written by Theon of Alexandria , Then it moved to Islamic civilization where Muslim scientists FULLY developed geared Astrolabes AND put manuals to it as it was crucial to Muslims to know prayer times and the direction to Mecca . Astrolabe moved to Europe through Spain/Andalus and Europeans made it again but in English and removed all the features that relate to Muslim prayers and added some other astrological information .

[@chrislusbytaylor3197]

As others have pointed out, you don't look at the sun when using an astrolabe. That's a sextant you're thinking of. You aim the alidade (not adilade) so that a spot of light passes through both holes in its vanes onto something other than your eye. You don't mention that the sun has the same altitude twice a day so you have to use your skill and judgement to tell whether it's morning or afternoon. At night, though, you can sight two or more stars. Only one position of the rete (pronounced reetee, not reet) will fit both of their altitudes. So it is actually far easier and more accurate to tell the time at night. It's also more accurate because the stars appear to rotate at a constant speed, unlike the sun which can be up to 16 minutes fast or slow. Also, near noon the sun's altitude hardly changes so it is almost useless. But at night the far simpler nocturnal is more practical for telling the time. The astrolabe was known to the ancient Greeks. Knowledge would have been lost were it not for the Muslims, and the Christians in Europe learnt from the Moors in Spain, but the earliest non-Muslim astrolabe in the world's biggest and best collection, in Oxford, is no earlier than 1320. So, to say that Christians used it before then is speculative. (Chaucer was late 14th century.) I really don't think millions and millions of people ever used astrolabes. They would have been far too expensive, and surely thousands would have survived. They haven't. The Islamic Museum in Cairo, the largest Islamic city on earth, has only a handful. No, millions and millions of people judged the time during the day from the lengths of their shadows. Muslims set their prayer times this way, too. All medieval churches in England are believed to have had sundials. The idea that people had "completely disposable" paper astrolabes in their back pockets seems utterly fanciful to me. Yes, there were eventually printed books containing pages that could be cut out and pasted onto card to make an astrolabe, but the card had to be laboriously and skilfully cut out to make a usable rete and you still needed a solid mater or it wouldn't hang straight. All the 'paper' astrolabes I'm aware of in museums have wood maters and paper-covered wood or card parts. Not exactly throw-away. Your explanation of the stereographic projection is wrong. It is a projection onto a plane parallel with the earth's equator, as seen from the south celestial pole. But this projection plane is above the pole, not below it as you say at 5:15. The difference is that your diagram would create a mirror image of the astrolabe. This projection does map circles onto circles and does preserve angles where they cross but it does not map straight lines onto straight lines as you state. You say the rete holds the positions of the sun, moon and planets, but that's not really true. I've never seen any attempt to show the moon or planets on a rete, although it's true that the planets orbit very close to the ecliptic. Perhaps you're thinking of the astrolabe in Oxford that shows the planets but on the back, not on the rete. You never explain the local coordinates on the plate, I feel. I think you should say that these are the altitude and azimuth (i.e. direction) of the sun and stars as seen by you standing at some point on the Earth. So, if the sun is, say, 30 degrees above the horizon and exactly south-west its altitude is 30 and its azimuth (from north, clockwise) is 225 degrees. It is these coordinates that you can locate on the altitude circles and azimuth arcs on the plate. If you want to use the astrolabe at a different latitude you will need a different plate.

[@chekhovian3226]

It's commonly thought that Chaucer was the author of the astrolabe manuscript discovered by Derek Price at the University of Cambridge's Peterhouse library. But it has since been established quite convincingly that a monk called Brother John of Westwick was the true author of the treatise. For an excellent account of this read 'The Light Ages: The Surprising Story of Medieval Science' by Seb Falk.

[@christopherellis2663]

Which would have been written in Latin. The English translation is Chaucer's work. See Robert of Chester for even earlier translations from Arabic into Latin.

[@BurnedJello]

Does he have glasses because he keeps staring at the sun when he's trying to sight the angle? Hold it in front of your torso and look for the shadow to line up

[@christopherellis2663]

The Quadrant is also good for these things. Spherical Trigonometry collapsed into a quarter circle 🔵 I have read Chaucer in Middle English. Declination and Hour Angle, Azimuth and Altitude.

[@LukeT1]

I have yet to find an explanation of the astrolabe which is clear. Every single one fails to show a closeup of the scale or whatever the hell it is that the star or sun angle is aligned to, including this video. You point the rule at the star or sun, and then what? I see you move the rete around, but what the hell are you lining up? SHOW A CLOSEUP!!!! After viewing several videos about astrolabes, I still don't know how to use one.

[@renukote]

LT T first you need a globebortion in order look at the astrolabe with a flat earth mentality

[@alexanderandro1895]

kzbin.info/www/bejne/hGnSiHqtmMl5o6M

[@TheAstralthief]

LT T Go to Archive.org and search chaucer. Its there. Download it to print and read it. Then read it again until you under stand it. Research helps. Keep in touch. Im into making these. ✌️💚. The Earth is flat. This is PROOF

[@johndelaurier6238]

You turn it on its back and line up a degree of a constellation.. Then flip it back over and line it back to to that degree. You peer through the back like a tube to alline it

[@anonymousbosch9265]

It sucks so bad that researching these great instruments of antiquity puts you in too close proximity to flat earth nonsense What is said about elegant design, form, and function is exactly why I’m interested them

[@duncankelly4354]

And yet it only works on a flat surface. Let me know when you find that on a ball.

[@lennydykstrasspankbank415]

@@duncankelly4354 Explain why it wouldn't work on a globe.

[@LOGOS_Official]

Lenny Dykstra's Spank Bank - explain how it would work on a globe. Because it doesn’t. You literally have to change earth to a flat surface for it to work did you not listen? Wtf.

[@alejandrocambraherrera8242]

@@LOGOS_Official Thatʼs why the astrolabe is based on a *projection* of a globe. The fact that you are working with a flat instrument does not imply that the world itself needs to be flat: the astrolabe is flat simply because it is easier to use and transport that way. There are also spherical astrolabes, if you prefer them.

[@LOGOS_Official]

@@alejandrocambraherrera8242 - so is the earth in quantum super position where both shapes are possible at the same time since that can both be explained with the observations

[@rasselrevolution3162]

i also like astrology islamic it's a real astrology .. good 👍

[@mwdasja1127]

I watch Wujec speech in TED also, but he did not say who found this device..

[@angelliv]

She called Mariam Al Asturlabi

[@BluegrassBuzzbomb]

Too many ads...

[@TheAstralthief]

Time is merely part of The cycle.

[@collettebonner6944]

In the Book of Jasher Benjamin used the astrolabe to locate his brother Joseph.

[@josephtang5459]

Geometry means geo and metry， science of measuring the Earth

[@redzonechannel4696]

Why you don't mentions this item from the Muslim creation?!!

[@jonathanengdahl9045]

Astrolabes existed hundreds of years before islam existed

[@iam.reverence]

The earth is flat.

[@trentp151]

Please provide any convincing evidence for that statement, please. Think of some water, sitting in a glass, creating a meniscus. Perhaps a meniscus the size of the earth would seem like a sort of dome of water to us, living on the ground. Seriously. Look at a meniscus in a glass, and you would think if there was an edge, there would be a place on earth where you could almost literally see the next state, or country, if being outside of the USA, and also, this phenomenon would be absolutely evident AROUND the world (in a circle) of what we think of as the world map.

[@garywybenga4188]

@@trentp151 so you're a concave earther

[@robbglow]

@@trentp151 stars spin around Polaris in a circle from the alleged ~1000 mph spin of earth but they don't streak sideways from the alleged ~66000 mph trek around the sun.

[@trentp151]

@@robbglow That proves absolutely nothing.

[@trentp151]

@@garywybenga4188 No, that makes no sense, since the Earth is a sphere that orbits the SUN. Just like every other planet in our solar system. Just like the Moon is a sphere that orbits the Earth. They weren't called the Heavenly Spheres for no reason.

[@boscovich11]

to be 2:15

[@davidandrews2742]

Astrolabe i think prove The Earth is Flat

[@AH-xt4xi]

You had a thought? That's surprising.

[@christopherellis2663]

Surely, you jest.

[@garywilcox4025]

Commercials are too numerous.

[@maxdecleyn]

an astrolabe takes account of how your globes (eyes) perceive the plane of existence. stop insulting their intelligence..

[@AdeobaDebayo-Doherty-zg6kj]

John 3:16

[@TheAstralthief]

Yes The Earth is flat. Says The Astral thief. ALWAYS 🤔✌🏽💚

[@lennydykstrasspankbank415]

Explain in detail why this wouldn't work on a globe.

[@rayclark7963]

Astro is a DOG, but hes NOT a lab....

[@deanhumble7379]

It was invented by a Greek woman

[@karlmchugh9996]

This absolutely proves the Earth is Flat and always has been .

[@juanrivera8495]

Yes, this is absolutely right and the undeniable truth of where we live. This magic device/instrument was designed with the flat earth or geocentric model in mind...the whole world during that time knew the earth was, still is and will always be flat.