Language Learning

Sun letters and moon letters are the Arabic alphabets classified into two categories. This classification is triggered by the Arabic definite article ال which is added to the beginning of indefinite words. Basically, the laam in the ال is assimilated to the sun letters but not to moon letters.

Image by Mohammed Thamir flickr.com

The assimilation happens because the sun letters and the laam are close to each when articulated; therefore, the laam gets assimilated to the sun letter that follows it. The sun letter, in turn, becomes doubled. This doubling is marked by shaddah on the sun letter. This only concerns the pronunciation, and the typography remains the same (i.e. the laam is written).

The reason for calling them sun letters and moon letters is the sharp contrast between these two one-of-a-kind heavenly objects. Sun in Arabic is شَمْس and moon is قَمَر. When adding the ال to the beginning, they become الشَّمْس (pronounced as اَشَّمْس) and القَمَر (no change in pronunciation). Therefore, the assimilation of ل to ش in الشَّمْس is taken as a representation of the sounds to which the ل gets assimilated, hence called sun letters الحُرُوف الشَّمْسِيَّة. Similarly, the non-assimilation of ل to ق is taken as a representation of the sounds that block the assimilation of ل, so they are called moon letters الحُرُوف القَمَرِيَّة.

If you look at the Arabic diagram presented in a previous lesson, you will notice that the letters that are produced / articulated from the vicinity of the laam are:

ت ، ث ، د ، ذ ، ر ، ز ، س ، ش ، ص ، ض ، ط ، ظ ، ل ، ن

The ج is treated as a sun letter only in Iraqi dialect of Arabic. The remaining letters in the inventory are too far from the laam; therefore, no assimilation occurs. The are the moon letters:

 أ ، ب ، ج ، ح ، خ ، ع ، غ ، ف ، ق ، ك ، م ، و ، هـ ، ي

In the examples below, you can see that the laam is assimilated to the following sun letter, but it is still written.