Astrolabe

alt=Planispheric Astrolabe made of brass, cast, with fretwork rete and surface engraving|thumb|North Africa, narị afọ nke 9 AD, Planispheric Astrolabe. Nchịkọta Khalili.
thumb|Astrolabe ọgbara ọhụrụ emere na Tabriz, Iran na 2013.
Astrolabe (Grik: ἀστρολάβος astrolábos, 'star-taker'; Arabic: ٱلأَسْطُرلاب al-Asṭurlāb ; Persian: ستاره‌یاب Setāreyāb) bụ ngwá ọrụ oge ochie. Ọ na eje ozi dị ka chaatị kpakpando na ihe atụ anụ ahụ nke ihe ndị dị n'eluigwe a na ahụ anya. Ọrụ ya dị iche iche na emekwa ka ọ bụrụ ihe nrịba ama na ngwaọrụ mgbako analọgụ nwere ike ịrụpụta ọtụtụ nsogbu na mbara igwe. N'ụdị ya kachasị mfe, ọ bụ diski igwe nwere ụkpụrụ nke wires, mbelata, na perforation nke na enye onye ọrụ ohere ịgbakọ ọnọdụ mbara igwe nke ọma. Ndị ọkachamara na enyocha mbara igwe na eji akụkọ ihe mere eme eme, ọ na enwe ike ịlele elu n'elu mbara igwe, ehihie ma ọ bụ abalị; enwere ike iji ya chọpụta kpakpando ma ọ bụ mbara ala, iji chọpụta latitude mpaghara nyere oge mpaghara (na nke ọzọ), nyocha, ma ọ bụ iji mee ka ọ dị n'akụkụ atọ. Ejiri ya mee ihe n'oge ochie, Islam Golden Age, European Middle Ages na Age nke Nchọpụta maka ebumnuche ndị a niile.

Astrolabe dị irè maka ịchọpụta latitude na ala ma ọ bụ oke osimiri dị jụụ. Ọ bụ ezie na ọ dịghị ihe a pụrụ ịdabere na ya n'elu elu ụgbọ mmiri nke nọ n'oké osimiri na esighị ike, e mepụtara astrolabe nke onye na akwọ ụgbọ mmiri iji dozie nsogbu ahụ.

## Ngwa
thumb|Ịkpụ osisi nke narị afọ nke 16 iji tụọ ịdị elu ụlọ nke nwere mbara igwe
Onye na enyocha mbara igwe nke narị afọ nke 10 chepụtara na enwere ihe dị ka ngwa 1000 maka ọrụ dị iche iche nke astrolabe, ma ndị a sitere na mbara igwe, mbara igwe na nke okpukperechi, ruo n'oge na oge nchekwa oge na tebụl mmiri. N'oge a na eji ha eme ihe, a na ele ịgụ kpakpando anya dị ka sayensị siri ike dị ka mbara igwe, na ọmụmụ ihe abụọ ahụ gara n'aka. Mmasị mbara igwe dị iche iche n'etiti nyocha mbara igwe ndị mmadụ (nke ọdịnala tupu Islam na Arabia) bụ nke metụtara nleba anya nke eluigwe na nke oge, na mbara igwe mgbakọ na mwepụ, nke ga agwa omume ọgụgụ isi na ngụkọ ziri ezi dabere na nyocha mbara igwe. N'ihe gbasara ọrụ okpukperechi nke astrolabe, ihe ndị a chọrọ n'oge ekpere Islam kwesịrị ikpebisi ike na mbara igwe iji hụ na usoro iheomume kwa ụbọchị, na qibla, ntụzịaka nke Mecca nke ndị Alakụba ga ekpe ekpere, nwekwara ike ikpebi site na ngwaọrụ a. Na mgbakwunye na nke a, kalenda ọnwa nke a na akọwa site na ngụkọ nke astrolabe dị oke mkpa maka okpukpe Islam, n'ihi na ọ na ekpebi ụbọchị nke ememe okpukpe dị mkpa dị ka Ramadan.

## Etymology
Akwụkwọ ọkọwa okwu Oxford na enye ntụgharị asụsụ “star taker” maka okwu bekee astrolabe wee tụpụta ya site na Latin ochie gaa na okwu Grik ἀστρολάβος : astrolábos, sitere na ἄστρον : astron “kpakpando” na ν: taketabάne.

Na ụwa Alakụba mgbe ochie, e nyere okwu Arabic al Asturlāb (ya bụ, astrolabe) ụkpụrụ dị iche iche. N'edemede Arabic, a sụgharịrị okwu ahụ ka ọ bụrụ ākhidhu al Nujūm (Arabic: آخِذُ ٱلنُّجُومْ, lit. 'star taker'), ntụgharị okwu Grik kpọmkwem.[5]

Al-Biruni hotara na akatọ ọkà mmụta sayensị oge ochie Hamza al Isfahani onye kwuru:[5] "asturlab bụ arabization nke Persia a nkebi ahịrịokwu" (sitara yab, nke pụtara "na ewere nke kpakpando").[6]. Na isi mmalite Islam nke etiti oge ochie, enwekwara usoro ọdịnala nke okwu ahụ dị ka "ahịrị ụlọ nyocha", ebe "Lab" na ezo aka na ụfọdụ nwa Idris (Enoch). Otu ọkà mmụta sayensị narị afọ nke 10 aha ya bụ al Qummi kwuru banyere usoro ọmụmụ a mana al Khwarizmi jụrụ ya.[7]

## Akụkọ ihe mere eme

### Ụwa ochie
thumb|Armillary Sphere mosaic sitere na Casa di Leada na Sountum na Sicily.
Apollonius nke Perga chepụtara astrolabe mbụ n'ime mmepeanya ndị Hellenistic n'etiti 220 na 150 BC, nke a na akpọkarị Hipparchus. Astrolabe bụ alụm di na nwunye nke planisphere na dioptra, n'ụzọ dị irè ihe mgbako analọgụ nwere ike ịrụpụta ọtụtụ nsogbu dị iche iche na mbara igwe. Ngosipụta mbụ ama ama nke astrolabe bụ mosaic dị na Casa di Leada na Solungum na Sicily, nke nwere ike ịbụ na esitere na Aleksandria na Egypt ebubata.[10] [nke na adịghị mma]

Theon nke Aleksandria (c. 335 – c. 405) dere nkọwa zuru ezu banyere astrolabe, na Lewis[11] na 

arụ ụka na Ptolemy ji astrolabe mee nchọpụta mbara igwe nke edere na Tetrabiblos. A  a-ekwu na ọ bụ nwa nwanyị Theon Hypatia (c. 350–370; nwụrụ na 415 AD), ma n'ezie, a maara na ejirilarị ya ma ọ dịkarịa ala afọ 500 tupu a mụọ Hypatia. Nkọwapụta a sitere na nkọwahie nke nkwupụta dị n'akwụkwọ ozi nke nwa akwụkwọ Hypatia Synesius dere (c. 373 – c. 414), nke kwuru na Hypatia kụziiri ya otú e si arụ ụgbọ elu astrolabe, ma o kwughị ihe ọ bụla banyere ya chepụtara ya. ya onwe ya.

A nọgidere na eji Astrolabes eme ihe n'ụwa ndị na asụ Grik n'oge nile nke Byzantium. N'ihe dị ka n'afọ 550 AD, Onye Kraịst bụ́ ọkà ihe ọmụma bụ́ John Philoponus dere ihe odide banyere mbara igwe n'asụsụ Grik, bụ́ nke bụ ihe odide mbụ dị n'ihe e ji ngwá ọrụ eme ihe. n'etiti narị afọ nke asaa.[lower-alpha 2] Sebokht na ezo aka na astrolabe dị ka ọla kọpa na mmalite nke akwụkwọ ya, na egosi na astrolabe metal bụ ndị a ma ama na Ndị Kraịst East nke ọma tupu e mepụta ha na ụwa Islam ma ọ bụ n'ụwa. Latin West.

Ngwọta Renaissance nke mbụ na ekwu banyere nsogbu sayensị gbadoro ụkwụ na ọrụ oge ochie na mbụ ma na emetụtakarị ozizi Ptolemaic. [Ihe ndekọ achọrọ]

### Oge ochie
Azụlitekwara astrolabes na ụwa Islam mgbe ochie, ebe ndị Alakụba na enyocha mbara igwe webatara akpịrịkpa angular na nhazi ahụ,agbakwunye okirikiri na egosi azimuths na mbara igwe. A na eji ya eme ihe n'ụwa nile nke ndị Alakụba, nke kachasị dị ka ihe enyemaka maka ịnyagharị na dịka ụzọ ịchọta Qibla, ntụziaka nke Mecca. Ọkammụta mgbakọ na mwepụ na narị afọ nke asatọ Muhammad al-Fazari bụ onye mbụ e kwuru na ọ bụ ya mere astrolabe na ụwa Alakụba.

Onye Alakụba na enyocha mbara igwe Albatenius hibere usoro mgbakọ na mwepụ n'akwụkwọ akụkọ ya bụ Kitab az Zij (c. 920 AD), nke Plato Tiburtinus (De Motu Stellarum) sụgharịrị gaa na Latịn. Astrolabe mbụ dị ndụ bụ ụbọchị AH 315 (927-928 AD). N'ụwa Islam, a na eji astrolabes chọta oge ọwụwa anyanwụ na ịrị elu nke kpakpando a kapịrị ọnụ, iji nyere aka ịhazi ekpere ụtụtụ (salt). Na narị afọ nke 10, al-Sufi buru ụzọ kọwaa ihe karịrị 1,000 dị iche iche ojiji nke mbara igwe, na mpaghara dị iche iche dị ka mbara igwe, ịgụ kpakpando, igodo, nyocha, idebe oge, ekpere, Salat, Qibla, wdg.

Spherical astrolabe bụ mgbanwe nke ma astrolabe na armillary sphere, chepụtara n'oge emepechabeghị anya site n'aka ndị na enyocha mbara igwe na ndị na emepụta ihe na ụwa islam. 892–902). Na narị afọ nke 12, Sharaf al-Dīn al-Tūsī chepụtara astrolabe linear, bụ́ nke a na akpọ mgbe ụfọdụ “ndị ọrụ al-Tusi”, bụ́ “mkpanaka osisi dị mfe nke nwere akara e dechara akwụkwọ ma na enweghị ihe nlegharị anya. ụdọ okpukpu abụọ maka ime nha akụkụ ma were ntụ ntụ gbawara agbawa." Abi Bakr nke Isfahan chepụtara igwe astrolabe ejikere na 1235.

Astrolabe metal mbụ ama ama na Western Europe bụ Destombes astrolabe nke emere site na ọla na narị afọ nke iri na otu na Portugal. Astrolaves metal ezere ọgụ nke nnukwu osisi na adịkarị mfe, na ekwe ka owuwu nke ibu na ya mere ndị ọzọ ezi ngwá. Astrolabe metal dị arọ karịa ngwá ọrụ osisi ndị hà nhata, na eme ka ọ na esiri ike iji ha eme njem.

Herman Contractus nke Reichenau Abbey, nyochara ojiji nke astrolabe na Mensura Astrolai na narị afọ nke 11. Peter nke Maricourt dere akwụkwọ akụkọ banyere iwu na ojiji nke astrolabe nke eluigwe na ala na ọkara ikpeazụ nke narị afọ nke 13 nke isiokwu ya bụ Nova compositio astrolabii particularis. Enwere ike ịchọta ụwa niile na History of Science Museum na Oxford. David A. King, ọkọ akụkọ ihe mere eme nke islam instrumentation, na akọwa eluigwe na ala astrolobe mere site Ibn al-Sarraj nke Aleppo (aka Ahmad bin Abi Bakr; fl. 1328) dị ka "kasị ọkaibe astronomical ngwá site dum Medieval na Renaissance oge".

Onye odee Bekee Geoffrey Chaucer (c. 1343–1400) chịkọtara A Treatise on the Astrolabe maka nwa ya nwoke, dabere na ọrụ Messahalla ma ọ bụ Ibn al-Saffar dere. Onye France na enyocha mbara igwe na onye na agụ kpakpando bụ́ Pélerin de Prusse na ndị ọzọ sụgharịrị otu akwụkwọ ahụ. Akwụkwọ mbụ e biri ebi na astrolabe bụ Composition and Use of Astrolabe by Christian of Prachatice, na ejikwa Messahalla, mana ọ dịtụbere.

Na 1370, Jain na enyocha mbara igwe bụ Mahendra Suri dere akwụkwọ akụkọ India mbụ banyere mbara igwe, nke akpọrọ Yantrarāja.

Ndị na akwọ ụgbọ mmiri ji astrolabe dị mfe nghọta, nke a maara dị ka balesilha, mee ihe iji nweta ọgụgụ ziri ezi nke latitude mgbe ọ nọ n'oké osimiri. Onye isi ala Henry (1394–1460) kwalitere ojiji nke balesilha mgbe ọ na aga Portugal.

Ọ fọrọ nke nta ka ọ bụrụ na ọ bụ Gerbert nke Aurillac (Pope Sylvester nke Abụọ nke ga-abịa n'ọdịnihu) wetara astrolabe ahụ n'ebe ugwu nke Pyrenees, bụ́ ebe e tinyere ya na quadrivium n'ụlọ akwụkwọ dị na Reims, France, obere oge tupu mmalite nke narị afọ nke 11. Na narị afọ nke 15, onye France na emepụta ngwá ọrụ bụ Jean Fusoris (ihe dị ka 1365–1436) malitekwara imegharị na ire astrolabes n'ụlọ ahịa ya dị na Paris, yana obere anwụ anwụ na ngwaọrụ sayensị ndị ọzọ a ma ama n'oge ahụ.
áká_èkpè|thumb|Nkọwa nke ngwa mbara igwe nke Ieremias Palladas 1612
Mmadụ iri na atọ n’ime ndị na agụ kpakpando dị ndụ ruo taa. Otu ihe atụ pụrụ iche nke ịrụ ọrụ nkà ná mmalite Europe narị afọ nke 15 bụ mbara igwe nke Antonius de Pacento mere nke Dominicus de Lanzano mere, nke e dere na 1420.

Na narị afọ nke 16, Johannes Stöffler bipụtara Elucidatio fabricae ususque astrolabii, akwụkwọ ntuziaka nke iwu na ojiji nke astrolabe. Astrolabes nke narị afọ nke 16 yiri nke anọ nke Georg Hartmann mere na enye ụfọdụ ihe akaebe mbụ maka mmepụta ogbe site na nkewa ọrụ. Na 1612, onye Gris na ese ihe bụ Ieremias Palladas webatara astrolabe ọkaibe na eserese ya nke na egosi Catherine nke Alexandria. Aha eserese a bụ Catherine nke Aleksandria ma gosikwa ngwaọrụ akpọrọ System of the Universe (Σύστημα τοῦ Παντός). Ngwaọrụ ahụ gosipụtara mbara ala ndị nwere aha n'asụsụ Grik: Selene (ọnwa), Hermes (Mercury), Aphrodite (Venus), Helios (Sun), Ares (Mars), Zeus (Jupiter), na Chronos (Saturn). Ngwa ahụ gosikwara akụkụ mbara igwe na eso ụdị Ptolemaic na ụwa egosipụtara dị ka okirikiri na acha anụnụ anụnụ nwere okirikiri nke nhazi mpaghara. Ahịrị dị mgbagwoju anya na anọchi anya axis nke ụwa kpuchiri ngwa ọrụ ahụ dum.
 

### Astrolaves na clocks
thumb|Amerigo Vespucci na ekiri Southern Cross site n'ile anya n'elu nke Armillary Sphere nke a na esi n'elu dị ka ọ bụ astrolabe, mana enweghị ike iji astrolabe mee ihe site n'ile anya n'elu ya. Ibe ahụ enweghị nkọwa nwere okwu ahụ bụ "Astrolabium," nke Jan Collaert II dere. Ụlọ ihe ngosi nka Plantin Moretus, Antwerp, Belgium.
Astrolabe na emetụta clocks na arụ ọrụ na mbara igwe na mbụ; enwere ike ịhụ ha n'ọtụtụ ụzọ dị ka astrolabes na arụ ọrụ clockwork nke e mere iji mepụta ngosipụta mgbe niile nke ọnọdụ anyanwụ, kpakpando, na mbara ala dị ugbu a. Dịka ọmụmaatụ, elekere Richard nke Wallingford (ihe dị ka 1330) nwere n'ụzọ bụ isi nke map kpakpando na atụgharị n'azụ ret a kapịrị ọnụ, nke yiri nke astrolabe.[38]

Ọtụtụ elekere na mbara igwe na eji ihe ngosi ụdị mbara igwe, dị ka elekere a ma ama na Prague, na ewere ntule stereographic (lee n'okpuru) nke ụgbọ elu eklips. N'oge na adịbeghị anya, elekere astrolabe aghọwo ihe a ma ama. Dị ka ihe atụ, Dr. Ludwig Oechslin, onye Switzerland na ese nche kpụrụ ma wuo elekere astrolabe na njikọ ya na Ulysse Nardin na 1985. Onye Netherlands na ese nche bụ Christaan van der Klauuw na arụpụtakwa elekere astrolabe taa.

## Ihe owuwu
Astrolabe nwere diski, nke a na akpọ mater (nne), nke dị omimi nke na ejide otu efere ma ọ bụ karịa nke a na akpọ tympans, ma ọ bụ ihu igwe. A na eme tympan maka otu ebe a kapịrị ọnụ ma kanye ya na ntule stereographic nke okirikiri na egosi azimuth na elu ma na anọchi anya akụkụ nke mbara igwe dị n'elu mbara mpaghara. A na agụkarị akụkụ nke mater n'ime awa oge, ogo nke arc, ma ọ bụ abụọ.

N'elu mater na tympan, rete, usoro nke nwere ntule nke ụgbọ elu ecliptic na ọtụtụ ihe nrịbama na egosi ọnọdụ nke kpakpando kachasị mma, nweere onwe ya ịtụgharị. Ihe nrịbama ndị a na abụkarị isi ihe dị mfe, mana dabere na nka nke onye omenkà nwere ike ịkọwapụta na nka. Enwere ihe atụ nke astrolabes nwere ihe ngosi nka n'ụdị bọọlụ, kpakpando, agwọ, aka, isi nkịta, na akwụkwọ, n'etiti ndị ọzọ. A na-akanyekarị aha kpakpando ndị ahụ n'akwụkwọ nrụtụ aka n'asụsụ Arabik ma ọ bụ Latịn. Ụfọdụ astrolabes nwere iwu dị warara ma ọ bụ akara nke na agbagharị n'elu rete, ma enwere ike iji ọnụ ọgụgụ nke mbelata.

Rete, na anọchite anya mbara igwe, na arụ ọrụ dị ka chaatị kpakpando. Mgbe ọ na atụgharị, kpakpando na eklips na agagharị n'elu ntule nke nhazi na tympan. Otu ntụgharị zuru oke dabara na ngafe nke otu ụbọchị. Ya mere, astrolabe bụ onye bu ụzọ nke planisphere nke oge a.

N'azụ mater, a na akanyekarị ọtụtụ akpịrịkpa ndị bara uru na ngwa dị iche iche nke astrolabe. Ndị a dịgasị iche site na onye nrụpụta gaa na onye nrụpụta, mana nwere ike ịgụnye usoro ntụgharị maka ntụgharị oge, kalenda maka ịtụgharị ụbọchị nke ọnwa gaa na ọnọdụ anyanwụ n'elu eklips, akpịrịkpa trigonometric, na ngụsị akwụkwọ nke ogo 360 n'akụkụ azụ azụ. A na ejikọta alidade na ihu azụ. Enwere ike ịhụ otu alidade n'ihe atụ aka nri ala nke mbara igwe Persian dị n'elu. Mgbe a na ejide astrolabe na kwụ ọtọ, a pụrụ ịtụgharị alidade na anyanwụ ma ọ bụ kpakpando n'ogologo ya, ka e wee nwee ike ịgụ elu ya na ogo ("were") site na nsọtụ astrolabe gụsịrị akwụkwọ; ya mere okwu a sitere na Greek mgbọrọgwụ: "astron" (ἄστρον) = kpakpando + "lab-" (λαβ-) = iji.

Oghere onyinyo na apụtakwa n'azụ ụfọdụ astrolabes, nke ndị ọkachamara na agụ kpakpando Muslim mepụtara na narị afọ nke itoolu, ebe ngwaọrụ nke omenala Greek oge ochie nwere nanị ihe ọ̀tụ̀tụ̀ dị elu n'azụ ngwaọrụ ndị ahụ. A na eji nke a gbanwee ogologo onyinyo na ịdị elu nke anyanwụ, nke ojiji ya dị iche iche site na nyocha ruo n'ịdị elu na enweghị ike iru.

Ndị na emepụta ha na-abịanyekarị aka na ngwaọrụ na ihe odide dị n'azụ astrolabe, ma ọ bụrụ na e nwere onye na elekọta ihe ahụ, aha ha ga apụta n'ihu, ma ọ bụ n'ọnọdụ ụfọdụ, aha nke sultan na  achị achị ma ọ bụ onye na achị achị. A chọpụtakwara onye nkụzi nke ndị na agụ kpakpando na egosi na e dere ya n'ebe a. A na abịanyekwa aka n'ụbọchị a rụrụ ihe astrolabe, nke mere ka ndị ọkọ akụkọ ihe mere eme chọpụta na ngwaọrụ ndị a bụ ngwá ọrụ sayensị nke abụọ kasị ochie n'ụwa. Ihe odide ndị dị na mbara igwe kwekwara ka ndị ọkọ akụkọ ihe mere eme kwubie na ndị na enyocha mbara igwe na achọsi ike na emepụta ihe nkiri nke ha, ma na e mekwara ọtụtụ ndị ka ha nye iwu ma debe ha n'ahịa ka ha ree, na egosi na e nwere ụfọdụ ahịa nke oge a maka ngwaọrụ ndị ahụ.

Akụkụ nke astrolabe ahụ nwere diski okirikiri, tube a na ahụ anya, alidade, na ogwe aka ndị nwere ihe ọ̀tụ̀tụ̀ e gụchara. Disk okirikiri bụ akụkụ bụ isi nke astrolabe. A na ejikarị ya ele ihe oyiyi na mbara igwe. A na etinye tube na ahụ anya n'elu diski okirikiri ma jiri ya hụ kpakpando ma ọ bụ mbara ala. Alidade nwere ntutu isi kwụ ọtọ na kwụ ọtọ nke na atụpụta ebe dị na mgbanaka azimuthal nke a na akpọ almucantar ( okirikiri dị anya). Ogwe aka a na-akpọ radius na ejikọta site na etiti astrolabe na axis anya nke dị na ogwe aka ọzọ nke a na akpọkwa radius. Radiọs nke ọzọ nwere ngụsị akwụkwọ nke ịdị elu na nha anya.

## Ndabere mgbakọ na mwepụ
Ihe owuwu na imewe nke astrolabes dabere na ntinye nke ntule stereographic nke mbara igwe. Isi ebe a na emekarị ntule ahụ bụ South Pole. Ụgbọ elu nke a na atụ anya ya bụ nke Equator.

### Ịmepụta tympanum site na ntule stereographic
thumb|Akụkụ nke Astrolabe tympanum
The tympanum na ejide anyụike nhazi nke celestial nke rete ga atụgharị na ya. Ọ bụ akụkụ nke ga enyere aka ikpebi kpọmkwem ọnọdụ kpakpando n'otu oge nke ụbọchị na afọ.

Ya mere, ọ ga arụ ọrụ:

#

#### Ebe okpomọkụ na equator na akọwa tympanum
thumb|Ntụle stereographic nke okpomọkụ ụwa na equator si na South Pole.

#  The blue sphere represents the celestial sphere.
#  The blue arrow indicates the direction of true north (the North Star).
#  The central blue point represents Earth (the observer's location).
#  The geographic south of the celestial sphere acts as the projection pole.
#  The equatorial plane serves as the projection plane.
# Three parallel circles represent the projection in the sky of Earth's main circles of latitude: 
#*  In orange, the Tropic of Cancer.
#*  In purple, the equator.
#* In green, the Tropic of Caprcorn.

Mgbe ị na atụba n'ụgbọelu equatorial, okirikiri atọ dị n'akụkụ atọ kwekọrọ na okirikiri atọ nke ụwa (akụkụ aka ekpe nke onyonyo a). Nke kachasị n'ime ndị a, Tropic of Capricorn, na akọwa nha nke tympanum nke astrolabe. Ebe etiti nke tympanum (na etiti nke okirikiri atọ) bụ n'ezie akụkụ ugwu ndịda nke ụwa na agbagharị gburugburu, ya mere, rete nke astrolabe ga atụgharị gburugburu ebe a ka awa nke ụbọchị gafere (n'ihi ụwa. ngagharị ngagharị).

The atọ concentric okirikiri na tympanum bara uru iji chọpụta kpọmkwem oge nke solstices na equinoxes n'ime afọ: ọ bụrụ na mmadụ maara na anyanwụ ọnọdụ na rete na ọnọdụ ya kwekọrọ na mpụta okirikiri nke tympanum (Tropic nke Capricorn), ọ na egosi. oyi solstice (anyanwụ ga anọ na zenith maka onye na ekiri na Tropic nke Capricorn, nke pụtara okpomọkụ na ndịda hel na oyi na ugwu ugwu). Ọ bụrụ na, n'aka nke ọzọ, ọnọdụ ya dabara na gburugburu ime (Tropic of Cancer), ọ na egosi oge okpomọkụ solstice. Ọ bụrụ na ọnọdụ ya dị na etiti etiti (equator), ọ dabara na otu n'ime equinoxes abụọ ahụ.

#### Ihu igwe na nha elu
thumb|Ntụle stereographic nke mbara ihu onye na ekiri n'otu ebe a kapịrị ọnụ
N'akụkụ aka nri nke foto nke mbụ:

#  The blue arrow indicates the direction of true north (the North Star).
#  The central blue point represents Earth (the observer's location).
#  The black arrow represents the zenith direction for the observer (which would vary depending on the observer's latitude).
#  The black circle represents the horizon surrounding the observer, which is perpendicular to the zenith vector and defines the portion of the celestial sphere visible to the observer.
#  The geographic south of the celestial sphere acts as the projection pole.
#  The equatorial plane serves as the projection plane. ext

thumb|Stereographic projection of the horizon and an almucantar.
Mgbe ị na atụgharị mbara igwe n'elu ụgbọ elu equatorial, ọ na agbanwe ka ọ bụrụ ellipse na agbago elu n'akụkụ akụkụ ugwu ndịda (etiti etiti tympanum). Nke a na egosi na akụkụ nke mbara igwe ga ada n'èzí mpụta nke tympanum (Tropic of Capricorn) na, ya mere, agaghị anọchi anya ya.

Na mgbakwunye, mgbe ị na ese okirikiri ndị kwekọrọ na mbara elu ruo zenith (almucantar), a na arụ grid nke ellipses na esochi, na enye ohere maka ikpebi ịdị elu kpakpando mgbe rete na adaba na tympanum a haziri (dị ka a hụrụ na foto nke abụọ).

#### Ndị meridian na nha nke azimuth
thumb|Ntụle stereographic nke ugwu ndịda meridian na meridian 40° E na tympanum nke astrolabe
N'akụkụ aka nri nke onyonyo a:

#  The blue arrow indicates the direction of true north (the North Star).
#  The central blue point represents Earth (the observer's location).
#  The black arrow represents the zenith direction for the observer (which would vary depending on the observer's latitude).
#  The black circle represents the horizon surrounding the observer, which is perpendicular to the zenith vector and defines the portion of the celestial sphere visible to the observer.
#  The red dots represent the zenith and nadir (the point on the celestial sphere opposite the zenith with respect to the observer).
#  The orange circle represents the celestial meridian (or meridian that goes, for the observer, from the north of the horizon to the south of the horizon passing through the zenith).
#  The red circle represents a secondary meridian with an azimuth of 40° East relative to the observer's horizon, and like all secondary meridians, it intersects the principal meridian at the zenith and nadir.
#  The geographic south of the celestial sphere acts as the projection pole.
#  The equatorial plane serves as the projection plane.

## Hụkwa

*

## Ntụaka

; Ihe odide ala ala peeji