8 9 5 ▁the ▁element ▁was ▁found ▁on ▁Earth . ▁In ▁ 1 8 6 9 ▁the ▁astronom ers ▁Charles ▁August us ▁Young ▁and ▁William ▁H ark ness ▁independently ▁observed ▁a ▁novel ▁green ▁emission ▁line ▁in ▁the ▁Sun ' s ▁cor ona ▁during ▁an ▁eclipse . ▁This ▁" new " ▁element ▁was ▁incorrectly ▁named ▁coron ium , ▁as ▁it ▁was ▁only ▁found ▁in ▁the ▁cor ona . ▁It ▁was ▁not ▁until ▁the ▁ 1 9 3 0 s ▁that ▁Walter ▁Gro tri an ▁and ▁Beng t ▁Ed l én ▁discovered ▁that ▁the ▁spectral ▁line ▁at ▁ 5 3 0 . 3   nm ▁was ▁due ▁to ▁highly ▁ion ized ▁iron ▁( Fe 1 3 + ). ▁Other ▁unusual ▁lines ▁in ▁the ▁cor onal ▁spectrum ▁are ▁also ▁caused ▁by ▁highly ▁charged ▁ ions , ▁such ▁as ▁nick el ▁and ▁calci um , ▁the ▁high ▁ion ization ▁being ▁due ▁to ▁the ▁extreme ▁temperature ▁of ▁the ▁solar ▁cor ona . ▁To ▁date ▁more ▁than ▁ 2 0 ▁ 0 0 0 ▁absor ption ▁lines ▁have ▁been ▁listed ▁for ▁the ▁Sun ▁between ▁ 2 9 3 . 5 ▁and ▁ 8 7 7 . 0   nm , ▁yet ▁only ▁approximately ▁ 7 5 % ▁of ▁these ▁lines ▁have ▁been ▁linked ▁to ▁element al ▁absor ption . ▁ ▁By ▁analyz ing ▁the ▁width ▁of ▁each ▁spectral ▁line ▁in ▁an ▁emission ▁spectrum , ▁both ▁the ▁elements ▁present ▁in ▁a ▁star ▁and ▁their ▁relative ▁abund ances ▁can ▁be ▁determined . ▁ ▁Using ▁this ▁information ▁stars ▁can ▁be ▁categor ized