What are sun and moon letters?
The definite article al- changes its pronunciation depending on whether the first letter of the noun is a sun letter (ت ث د ذ ر ز س ش ص ض ط ظ ل ن) or a moon letter (ء ب ج ح خ ع غ ف ق ك م ه و ي). With sun letters, the lam assimilates and the following letter is doubled. With moon letters, the lam is pronounced clearly.
With sun letters, skip the lam and pronounce the following letter with shaddah.
ت
ث
د
ذ
ر
ز
س
ش
ص
ض
ط
ظ
ل
ن
With moon letters, pronounce the lam clearly before the following letter.
ء
ب
ج
ح
خ
ع
غ
ف
ق
ك
م
ه
و
ي
Sun letters (الشمسية): 14 letters that assimilate the lam. Moon letters (القمرية): 14 letters that keep the lam.
Sun letterالرَّحْمَٰنِ
The letter ر is a sun letter. The lam assimilates and the ر is doubled.
Moon letterالْمَلِكِ
The letter م is a moon letter. The lam is pronounced clearly.
The article al- is the most common prefix in Arabic. Mastering sun and moon letters helps you read the Quran fluently.