SAYËRAHD

SAYËRAHD jirmhoi kaloni osmoniyand, ki dar atrofi Oftob az rui madorhoi ellipsshakl harakat karda, rushnoni Oftobro inikos namuda medurakhshand.
Odamon az qadimulayyom mushohida karda budand, ki dar bayni sitorahdoi osmon jirmhoi munire hastand, ki az yak burj to burji digar mavqeashonro ivaz karda, guyo sayr mekunand (az in sabab sayyora nom giriftaand). Bo chashmi nomusallah 5 sayyora (Zuhra, Mushtari, Mirrikh, Zuhal va Atorud)-ro didan mumkin ast. Se sayyorai digarro tanho bo yorii teleskop mushohida kardan mumkin ast. Az in jost, ki onho dar asrhoi 18—19, badi ikhtiroi teleskop kashf shudaand: Uran (soli 1781, V. Gershel), Neptun (soli 1846, J. Adams, U. Levere, I. Galle), Pluton (soli 1930, P. Lovell, K. Tombo). Gayr az 9 sayyorai kalon (az jumla Zamin) yakchand hazor sayyorahoi khurd (asteroidho) kashf shudaand, ko andozahoyashon gunogun buda, asosan dar bayni madorzoi Mirrikh va Mushtari harakat mekunand.

Sayyoraho az rui tariqi harakati ba chashm namoyonashon (dar bayni sitoraho) ba guruhhoi poyoni va boloi judo meshavand. Sayyorahoi poyoni (Atorud va Zuhra) zangomi zarakati zohirii khud dar osmon az Oftob chandon dur shuda nametavonand (Atorud ga ziyoda az 29°, Zuhra na ziyoda az 48°).. Sayyoradoi boloy (Mirrikh, Mushtari, Zuhra, Uran, Neptun, Pluton) az Oftob dar masofahoi kunjii dilkhoh (to 180°) mushohida meshavand.
Az rui khususiyathoi fiziki (zichb, andoza, surati charkhzani dar atrofi mehvar) va tarkibi khimiyavi sayyoraho ba guruhi zamini yo dokhili (Atorud, Zuhra, Zamin va Mirrikh), ki dar dokhili tasmai asteroidho harakat mekunand va ba sayyorahoi azim yo khud beruni (Mushtari, Zuhal, Uran, Neptun) judo meshavand. Sayyorahoi guruhi zamini ba Oftob khele nazdik joygir shudaand, massaashon nisbatan khurd, zichiashon (3,8— 5,5 g/sm) va davri dar atrofi mehvar charkhzaniashon (az 24 soat to 243 shaboruz) kalon ast. Sayyorahoi az in massai kalonu zichii khurd dorand va dar atrofi mehvarashon tez (dar davomi 10-15 soat) charkh mezanand. Hatto khurdtarini onho — Uran az jihati massa az tamomi sayyorahoi guruhi zamini panj karat kalontar ast. Zichii miyonai in sayyoraho ba zichii ob nazdik buda,
madorashon dar masofahoi az 5 to 30 v. a. choygir shudaand. Sayyorai nuhum Pluton, ki masofaash az Oftob ba hisobi miyona 39,5 v. a. ast, az rui andoza ba guruhi zamini va az rui tarkibi khimiyavi ba guruhi sayyorahoi azim nazdik ast.
Davri gardishi sayyoraho dar atrofi Oftob az 88 shaboruz (Atorud) to 249 sol (Pluton) meboshad. Agar harakati sayyorahoro az qutbi shimolii dunyo mushohida kunem, hamai sayyoraho dar atrofi Oftob ba yak samt (muqobili aqrabaki soat) ha-rakat mekunand. Hamvorihoi madori sayyoraho (gayr az Atorud va Pluton) ba ekliptika bo kunje moiland, ki az 3,4° khurdtar ast. Hamvorii ekvatori Atorud va Pluton ba hamvorii (madorashon ba andozai muvofiqan 7°va 17°moiland. Az in jost, ki faslhoi sol digar shuda meistand.
Dar sathi sayyorahoe, ki qarib yo tamoman atmosfera nadorand, tash- kilahoe dida meshavand, ki ba onho shartan nomhoi zamini dodaand (harchand, ki tabiati fizikii onho ba in nomho tamoman muvofiq iameoyad). Masalan, bahrhoi tiran Mirrikh bahr nabuda, mavzehoeand, ki nisbat ba digar mavzeho rushnoiro kamtar inikos mekunand. Dar borai sathi sayyoraho va tabiati fizikii onho 20 soli okhir tavassuti safinahoi kayhonb (apparathoi sovetii «Venera», «Mars», «Zond», «Vega» va amerikoi «Mariner», «Pioner», «Viking», «Voyacher») malumoti purqimat ba dast ovarda shudaast. Az in malumot va mushohidahoi ruizamini barmeoyad, ki Atorud va Mirrikh ba Moh khele monand, buda, sathashon az tanurahoi sershumor iborat budaast. In tanuraho dar natijai bo digar jismhoi osmoni barkhurdani sayyorahoi mazkur paydo shudaand, yane paydoishi meteoriti dorand. Qonuni taqsimoti tanuraho dar Moh, Mirrikh va Atorud muvofiqi andozadoyashon ba qonuni taqsimoti massahoi jismhoi meteoriti muvofiq meoyad. Dar sathi Atorud joyhoi hamvori doirashakl mavjudand, ki kalontarini onho— Kaloris 1300 km bar dorad. Mavjudiyati moddai tira va tanurahoi bo lava purshuda darak medihad, ki dar ibtihoi tarikhi Atorud dar qari on faoliyati vulqoni dar avj budaast. Dar sathi Zuhra mavzehoi halqashakle dastand, ki ba tanurahoi metyooritii Moh monand buda, diametrashon ba 35—150 km merasad. Dar sathi Zuhra tarqishi azime oshkor shudaast, ki daroziash 1500 km barash 150 km va chuquriash qarib 2 km meboshad. Tarqishi azimi sathi Mirrikh, ki Koprat nom dorad, 400 km darozi, 120 km bar va qarib 6 km chuquri dorad. Dar sathi Zuhra niz vulqone oshkor shudaast, ki diametri asosi on ba 300—400 km va balandiash ba 1 km barobar meboshad.
Sathi Zuhra nisbat ba Moh hamvortar boshad ham sokhti murakkab dorad; dar biyobonhot sangzori on osori faoliyati vulqoniyu tektoniki va boroni meteoriti dida meshavad. Vulqonhoi azim dar Mirrikh niz ba vositai apparathoi kayhoni oshkor karda shudaand, ki diametri kalontarini onho — Olimi 600 km va balandiash 22 km meboshad. Rasmhoi bevosita dar rui Mirrikh giriftashuda nishon medihand, ki qitahoi zardu norinjii on dar haqiqat az biyobonhoi sangzor iborat budaand.
Dar tuli bisyor solho diqqati olimonro kulohhoi safedi Mirrikh ba khud jalb mekardand, ki andozadoyashon dar zimiston ziyod shuda az ogozi tobiston cap karda khurd megardand va okhir onho nest meshavand. Qismi asosii kulohhoi safedi Mir-rikh az yakhi oksidi karbon va qismi khele nochizi onho az barfreza (qirav)-i az bughoi ob ba vujudomada iboratand. Tanurdhoi meteoritii sershumor dar sathi radifhoi Mirrikh — Fobos va Deymos niz oshkor shudaand. Solhoi okhir (1975— 1985) dar borai plazmai nazdisayyoragi va maydoni magnitii Zuhra va Mirrikh niz malumoti garonbahoi ilmi ba dast ovarda shud (ba tufayli tadqiqoti kayhonii olimoni soveti va amerikoi).
Soli 1977 ba vositai mushohidaho az samolyot halqahoi Uran va soli 1979 bo yorii apparati kayhonii amerikoi «Voyacher-1» halqahoi Mushtari oshkor shudand. Uran va Neptun nisbat ba Mushtari va Zuhal az jihati massa khurd buda, az jihati zichi kalontarand. Albedoi Pluton 0,5 buda, qismi ziyodi sathi on bo yakh va barfreza pushnda shudaast.
Harorati sayyoraho asosan ba masofai onho az Oftob vobasta ast. Harorati miyonai sathi Atorud shabona —162°S va ruzona qarib +350°S ro tashkil mekunad. Zuhra dar atrofi mehvarash dar davomi 243 shaboruz yak bor charkh mezanad. Azbaski vay ba samti aks charkh mezanad, yak shaboruzi Zuhra ba 58,5 shaboruzi zamini rost meoyad. Harorati miyona dar tarafi ruzonai Zuhra qarib +480°S buda, barobari az sath dur shudan ba hisobi dar yak km 8°—10° past shuda, dar balandii 25—30 km ba 270°S barobar meshavad.
Mirrikh az Oftob nisbat ba Zamin 1,5 bor durtar joygir shuda, atmosferai khele tunuk dorad.. Az in sabab boyad vay khunuktar boshad va haroratash shabona khele past faroyad. Gayr az in, az sababi kalon budani eksentrisiteti madori Mirrikh harorati nuqtai zerioftobii Mirrikh dar perigeliy (300 K) az harorati on dar afeliy (270 K) farq dorad. Andozagirihoi sershumor nishon medihand, ki harorati joyhoi qutbii Mirrikh qarib ba
200—210 K merasad. Agar Mirrikh dar perigeliy boshad, ruzona dar nazdi ekvator sathi sayyora to ba +25°C (298 K) garm shuda, haroratash begohi yakbora to ba sifr va shabona to ba — 80°S past meshavad, chunin atmosferai khelo tunukshudai on termin ruzona az Oftob giriftaashro nigoh doshta nametavonad. Harorati miyonai tarafi namoyoni Mirrikh ba —23°S barobar meoyad (az oni Zamin + 22°S).
Harorati miyonai qabati abrii Mushtari ba —150°S barobar ast, yane garmiafkanii Mushtari nisbat ba garmii az Oftob giriftai on du barobar ziyod meboshad. Pas yak qismi garmii Mushtari az qari on judo shuda mebaroyad. Harorati qabati abrii Zuhal qarib — 180°S meboshad, yane garmiafkanii Zuhal niz nisbat ba garmigiriash (az Oftob) 2,5 bor ziyodtar ast. Pas Zuhal ba monandi Mushtari manbai dokhilii energiya dorad, ki dar natijai fushurishi gravitatsioni (baroi Mushtari 0,1 sm/sol) ba vujud meoyad. Harorati miyonai Uran va Neptun muvofiqan 50 K va 40 K barobar ast. Harorati rui Pluton boshad, az 40 K (—233°S) besh nest.
Mavjudiyati atmosferai saiyoraro az rui «mushohidai to raft ba kanor tirashavii qutri sayera, tadrijan sust shudani durakhshonii sitoraho hangomi peshi onhoro giriftani sayyoraho, az rui mavjudiyati abrho va hokazo muayyan mekunand. Atmosferai Atorud khele tunuk buda, andaryak ba 106 mol/sm3 barobar ast. Fishori havo dar sathi on ba 10-12bar barobar meoyad, yane zichi dar on jo takhminan 107 mol/sm3 ast. Qarib 0,1% atmosferai Atorud az geliy iborat ast. Gidrogen va oksigen ba miqdori kam mavjudand. Atmosferai Zuhra, ki onro nakhustin bor olimi buzurgi rus M. V. Lomonosov soli 1761 (hangomi az rui qutri Oftob guzashtani Zuhra) kashf kardaast, asosan (97%) az gazi karbonat (S02) tarkib yoftaast. Qarib 2% havoi Zuhra az nitrogen va gazhoi inerti (khususan argon) iborat ast. Miqdori oksigen az 0,1% ham kamtar ast. Digar gazho SO, NS1, NG va gayra ba miqdori nochiz (kamtar az 0,01%) mavjudand. Dar balandihoi 65— 70 km shamolhoi khele sakht mevazand; surati onho to ba 360 km/soat (tufon) merasad. Zuhra misli Zamani ionosfera dorad. Balandtarin qabathoi atmosferai Zuhra (to 5,5 hazoo km) asosan az gidrogei iborat ast.
Dar atmosferai Mirrikh oksigen khele kam ast (0,3%). Ob ba namudi qabati tunuki barfreza yak qismi kami kulohhoi qutbii Mirrikhro faro giriftaast.
Mushtari va Zuhal kurahoi buzurgi magnitonida buda, magzi sakhte dorand. Okhiri az jihati andoza
taqriban ba Zamin barobar buda, ammo az vay dida zichtar ast. Atmosferaashoi boshad, az gidrogenu geliy tarkib yoftaast. (Tarkibi atmosferai digar sayyorahoi azim niz hamin guna ast.)
Dar Mushtari dogi surkhe namudor ast, ki guyo oshubi siklonii atmosfera meboshad. Andozahoi vay ba 14000X 35000 km barobar ast. Hozir dar sayyorahoi sistemam Oftob 43 radif oshkor shudaast. Zamin 1-to, Mirrikh 2, Mushtari 14, Zuhal 17, Uran 5, Neptun 3 va Pluton 1 radif dorand.
Zichii miyonai moddai sayyorahoi dokhili az zichii miyonai moddai sayyorahoi azim yakchand karat ziyod ast. Massai sayyorahoi azim nihoyat kalon ast; dar qari onho fishor bond khele baland boshad. Zichii miyonai Atorud khele kalon ast (5,52 g/sm3). Az in jo khulosa barovardan mumkin ast, ki magzi (yadroi) on az jihati zichi ba zichii ohan barobar buda, qarib 60% massai sayyoraro tashkil mekunad. Zuhra az rui andoza, massa va zichii miyona az Zamin chandon farq namekunad va ehtimol magzi on nisbat ba Zamin az ohan boytar boshad; massai Mirrikh nisbat ba Zamin dah bor khurdtar va zichiash 1,5 marotiba kamtar meboshad. Gumon meravad, ki radiusi magzi ohanini Mirrikh qarib 1000 km buda, 5% massai sayyoraro dar bar megirad. Radiusi Mushtari 70 850 km buda, massaash taqriban ba 2-1037 kg merasad. Dar dokhili Mushtari magzi sakhti ohanu silikatii radiusash 4000 km joygir shu-daast, ki haroratash ba 30 000° S merasad va sababi garmiafkanii Mushtari meboshad. Mushtari manbai purquvvati radioafkanishoti haroratist; gayr az in vay magnitosferai buzurgero dorost. Zuhal az rui sokhti dokhiliash ba Mushtari monand ast, vale halqaash kalontar ast. Bino ba malumoti az «Voyajer-1» rasida, halqai Zuhal sokhti murakkab doshta, tarkiban az anbuhi sadho haljahoi tangu tunuk iborat budaand, ki jo- jo ba soni torhoi argamchin ba ham pechidaand. Uran va Neptun taqriban yakkhel sokht dorand, haroratashon nisbatan past ast. Ehtimol magzhoi onho nisbatan kalon buda, az omekhtai yakh va payvastagihoi gidrogen, oksi-gen, karbon, nitrogen, sulfur va gayra iborat boshand.
Dar borai durtarin sayyorai sistemai Oftob Pluton hanuz malumoti kofi dastras nashudaast. Gumon meravad, ki dar pasi Pluton niz sayyorahoi digar hastand. Macalan, az rui tahlili madori kometahoi davri charkhzaniash kalon takhmin mekunand, ki hej naboshad boz 5 sayyorai transplutoni vujud dorand; agar onho mavjud boshand, nimtiri kaloni madorashon az 53 to 285 v. a. darozi doshta metavovand.
Masalai tashakkuli sayyoraho (az jumla Zamin) yake az muhimtarin va mushkiltarin vazifahoi ilm ast. Nazariyai kosmogonie, ki dar ili nufuzi kofi paydo kardan mekhohad, boyad dastavval ba manidodi khususiyathoi zerini harakati sayyoraho bipardozad:
1)Madorhoi sayyoraho qarib dar yak hamvorie (ekliptika) khobidaand, ki qarib ba hamvorit ekvatori Oftob rost meoyad.
2)Hamai sayyoraho dar atrofi Oftob ba samte harakat mekunand, ki ba samti charkhzanii Oftob rost meoyad.
3)Samti charkhzanii sayyoraho (ba gayr az Zuhra va Uran) dar atrofi mehvarashon bo samti davrzanii onho dar atrofi Oftob yakkhela ast.
4)Massai Oftob 99,86% massai hamai sistemai Oftobro tashkil mekunad, ammo momenti miqdori harakati on nisbat ba momenti miqdori harakati Sayëraho khele khurdast (2%). Dar bobati paydoishi sayyoraho yakchand farziya peshnihod shudaast. Bino ba farziyai olimi soveti O. Yu. Shmidt dar atrofi Oftob yak vaqtho abri kalonu khunuki gazu chang davr mezad. Dar natijai ba hamdigar barkhurdan hissachahoi in abr ba yakdigar mechaspidand va magzi sayyorahoi oyandaro ba vujud meovardand.
Ba qadri dar rui in guna magzho jam shudani modda madorhoi ellipsshakli onho toraft davrashakl gashta, khudi sayyorahoi oyanda dar masofahoi muayyan az Oftob joygir meshudand. Pas az in hangomi kosti elementhoi radioaktivi dar natijai judo shudani garmi qari sayyoraho (az on chumla Zamin) muntazam garm meshud, ki in boisi tabiati vulqoni doshtani Sayyora, dar onho paydo shudani atmosfera, gidrosfera va gayra megardad. Masalai chi tavr dar atrofi Oftob paydo shudani abri gazu chang holo zal nashudaast. Gumon meravad, ki in abri gazu chang hangomi tashakkuli Oftob paydo shudaast. Nig. Niz Kosmogoniya.
Ad.: Brandt Dj. Khodj P„ Astrofizika solnechnoy sistemi, M., 1957; Bronshteyn V. A., Planeti i ikh nablyudenie, M., 1979.
P. Bobojonov.