shīn mīm sīn
l-shamsi, l-shamsu, l-shamsa (masculine noun) = the sun
qāf mīm rā
l-qamari, l-qamaru, l-qamara (masculine noun) = the moon
kāf sīn fā
kisafan = fragments
kusuf = solar eclipse
Salat-al-Kusuf = Solar Eclipse prayer
khā sīn fā
khasafa = darken, becomes dark
khasaf = cause to swallow
khusuf = lunar eclipse
Salat-al-Khusuf = Lunar Eclipse prayer
Some scholars considered the eclipse prayers are Sunnat-ul-mu’akkadah (prayers that are offered regularly by Prophet Muhammad sallallahu ‘alayhi wa salaam and the Prophet has recommended his followers to do so). Other scholars considered these prayers Wajib (prayer that comes next in rank of Obligatory prayers, in accordance to the importance attached to it by Prophet Muhammad sallallahu ‘alayhi wa salaam).
The eclipse prayer commences during the eclipse, but it can end after the eclipse itself ends.
Surah Saba 9
afalam yaraw ilā mā bayna aydīhim wamā khalfahum mina l-samāi wal-ardi
in nasha nakhsif bihimu l-arda aw nusqit ‘alayhim kisafan mina l-samāi
inna fi dhālika laāyatan likulli ʿabdin munībin
Then do they not look at what is before them and what is behind them, of the heaven and the earth?
If We so decide, We can cause the earth to swallow them, or cause fragments from the sky to fall upon them
Indeed, in that there is surely a Sign for every slave who turns to Allah
Surah Al-Qiyamah 6-10
yasalu ayyāna yawmu l-qiyāmati
fa-idhā bariqa l-basaru wakhasafa l-qamaru wajumi’a l-shamsu wal-qamaru
yaqūlu l-insānu yawma-idhin ayna l-mafaru
Man asks, when is the Day of Resurrection?
So when the vision is dazzled, and the moon becomes dark, and the sun and the moon are joined
Man will say on that Day, where is the escape?
Informative link here