What are sun and moon letters?

When the Arabic definite article ال (al-) attaches to a noun, the lam either assimilates or stays. The 14 sun letters cause the lam to assimilate so the following consonant doubles, as in ash-shams (the sun). The 14 moon letters leave the lam pronounced, as in al-qamar (the moon). The names come from these two example words.

Which letters are sun letters?

The 14 sun letters are ت ث د ذ ر ز س ش ص ض ط ظ ل ن. They are mostly the coronal consonants, pronounced near where the tongue touches for lam, which is why assimilation is natural. The remaining 14 letters are moon letters.

How does the tool find the right letter?

For each word it strips vowel marks and skips a leading definite article ال, then takes the first remaining consonant. That consonant determines whether the word is sun or moon, since assimilation is governed by the letter the article attaches to, not the alif-lam itself.

Does spelling change for sun letters?

No. The lam is still written in both cases; only the pronunciation changes. In fully vowelled text a sun letter takes a shadda (doubling mark) and the lam loses its vowel, but the alif-lam is always spelled. This tool classifies by pronunciation, not by adding marks.

Is my text kept private?

Yes. Classification happens entirely in your browser by comparing the leading letter against the sun and moon letter sets. Nothing you enter is uploaded, logged, or stored.

Arabic Sun/Moon Letter Checker

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Sun letters, moon letters, and the article al-

Learning to read Arabic aloud means knowing when the lam of the definite article ال (al-) is pronounced and when it vanishes into the next consonant. This split between 14 sun letters and 14 moon letters is one of the first pronunciation rules students meet. This tool classifies every word you enter so you can see the pattern.

How it works

The rule depends entirely on the first letter of the noun the article attaches to. The tool strips diacritics, skips a leading ال, and tests the next consonant:

الشمس -> first letter ش (sheen) -> sun  -> pronounced "ash-shams"
القمر -> first letter ق (qaf)   -> moon -> pronounced "al-qamar"

The 14 sun letters are ت ث د ذ ر ز س ش ص ض ط ظ ل ن — largely the coronal consonants articulated near the lam. The other 14 letters are moon letters. Sun-letter words are highlighted warm; moon-letter words cool.

Tips and example

The classic teaching pair is الشمس (ash-shams, the sun) versus القمر (al-qamar, the moon). Remember the spelling never changes — the alif-lam is always written; only the sound shifts, and in vowelled text the sun letter gains a shadda. If you study Persian, the related ezafe detector handles a different but equally invisible pronunciation rule.