En knivskarp bild av den totala solförmörkelsen 1919
För nästan exakt 100 år sedan inträffade en fantastisk total solförmörkelse. Men en totalitet som varade mästan 7 minuter var detta den längsta som hade inträffat på 500 år. Förmörkelsen användes också av astronomer för att testa den då nya relativitetsteorin – med ett positivt och omvälvande resultat.
Einstein publicerade den allmänna relativitetsteorin 1915 och den totala solförmörkelsen fyra år senare bjöd på optimala förhållanden för att testa den experimentellt. Kunde solens enorma gravitation avböja ljuset från bakomliggane stjärnor, som teorin förutsade? Under förmörkelsen blockerade månens skiva solljuset och gjorde stjärnor nära solen synliga på dagtid. Genom att mäta stjärnornas positioner och jämföra dem med deras positioner nattetid, då solen inte är i närheten, skulle man kanske kunna avgöra om gravitationen kunde påverka ljusstrålarna.
Tre astronomer, Arthur Eddington, Frank Watson Dyson och Andrew Crommelin, spelade en central roll i experimentet. Eddingon och Crommelin reste till två platser där förmörkelsen skulle vara total – den västafrikanska ön Principe och Sobral i Brasilien – medan Dyson koordinerade försöket från England.
Eddington och Crommelin avbildade solen med dåtidens teknologi: fotografiska plåtar av glas. Tyvärr har originalplåtarna från expeditionen 1919 gått förlorade, men kopior av en av plåtarna delades med astronomer världen över för att de själva skulle ta del av bevisen för relativitetsteorin. En kopia sändes till Landessternwarte Heidelberg-Königstuhl där glasplåten nyligen skannades inom ramen för IHAP-projektet (Heidelberg Digitized Astronomical Plates) [1].
Denna bild kan vara den skarpaste som finns av 1919 års solförmörkelse, tack vare avancerad digital bildbehandling av originalskanningen – bildrestaurering, brusreduktion och defektreduktion. Bilden visar fina detaljer i koronan, en jättelik protuberans som sträcker sig ut från solens högra sida, och de stjärnor i Oxens stjärnbild som användes för att bekräfta relativitetsteorin förutsägelser [2].
Kommentarer
[1] IHAD finansieras av Klaus Tschirastiftelsen (bidragsnr 00.071.2005). Den ursprungliga bildskanningen av glasplåten, innan den digitala restaureringen, visas av historiska skäl.
[2] Dysons originalartikel avslutas med det banbrytande diagrammet på sidan 332 som visar stjärnornas positionsavvikelse mot deras avstånd från solskivans centrum. Diagrammet visar att stjärnornas avvikelser är större ju närmare solen de befinner sig (svart heldragen linje), och med ungefärligen det belopp som förutsades av relativitetsteorin (dubbelt så stor som Newtons teori, prickad linje).
ESO/Landessternwarte Heidelberg-Königstuhl/F. W. Dyson, A. S. Eddington, & C. Davidson
Om bilden
| ID: | potw1926a |
| Språk: | sv |
| Typ: | Planetarisk |
| Publiceringsdatum: | 1 juli 2019 06:00 |
| Storlek: | 23800 x 14191 px |
Om objektet
Bildformat
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