Sun and Moon Letters: Why al- Changes Sound

What Are Sun and Moon Letters?

Arabic puts al- at the start of a word to mean “the”. It is written as alif and lam (ال). The sound of that lam depends on the first letter of the word that follows.

If the word starts with a sun letter, the lam blends into that letter. If it starts with a moon letter, the lam is heard as normal.

The names come from two words. The sun is الشمس and it is said ash-shams. The moon is القمر and it is said al-qamar.

How Does al- Change Before a Sun Letter?

Before a sun letter, the lam takes on the sound of the next consonant. That consonant is then said twice, as one longer sound. The Nile is an-Nil, not al-Nil.

Notice what stays fixed. Both words are written with alif and lam. Only the speech changes, and the page you read looks the same either way.

Which Letters Are Sun Letters and Which Are Moon Letters?

Each group has exactly 14 letters. The two lists below use the alphabet order, and the figure shows both at once.

The 14 Sun Letters

The third column shows how the start of the word sounds with al-. For example, “at-t” means the lam becomes a t sound.

The 14 Moon Letters

Here the lam is always heard. Some lists show hamza (ء) in the place of alif. The hamza page covers its value.

Lam itself is a sun letter, so اللون (the color) is said al-lawn. The sound looks unchanged because the lam blends into another lam.

Why Are They Called Sun and Moon Letters?

Linguists describe the sun letters as coronal consonants. These are sounds made with the tip or blade of the tongue, such as t, n, r and s. The moon letters are made elsewhere, such as b, k, m and w.

That gives a rough guide for learners. If the first sound uses the front of the tongue, it is probably a sun letter.

A Few Edge Cases

• Jim (ج) is a moon letter in standard Arabic. In some spoken dialects, such as Moroccan, Mesopotamian and Palestinian, it acts like a sun letter.
• Heavy letters such as ط and ص are sun letters. In some dialects only the place of the sound blends in, not the heaviness.
• Everyday speech does not always follow the textbook rule.

How Can You Remember the Moon Letters?

Teachers often use a short memory line that holds all 14 moon letters. It is read as ابغ حجك وخف عقيمه. Its letters are exactly the moon list, and the code checks it.

Once you know the moon letters, every other letter is a sun letter. Learning 14 is easier than learning 28.

The line also behaves nicely in Ilm-ul-Adad. The values of its four words add up to 1945, the same as the 14 moon letters one by one.

How Are Sun and Moon Letters Written?

Ordinary Arabic text never shows the difference. The alif and lam are always written, even when the lam is not said. Fully marked texts show it with small signs.

1. Before a sun letter, a shadda (ّ) goes on the first letter of the word, as in الشَّمْس.
2. Before a moon letter, a sukun (ْ) can go on the lam, as in الْقَمَر.
3. When another word comes before, the alif of al- is not said but is still written.

Teaching books sometimes add these marks. The Arabic letter forms page shows how the letters change shape in a word.

Does the Rule Change Abjad Values?

No. Ilm-ul-Adad counts the letters that are written, and the lam is written in both cases. So the article adds the same amount to every word: alif 1 plus lam 30, which is 31.

ا 1 + ل 30 + ش 300 + م 40 + س 60 = 431

ا 1 + ل 30 + ق 100 + م 40 + ر 200 = 371

The sun word and the moon word are counted by the same steps. The only thing that differs is the letters themselves.

Some calculators leave the article out and count only the noun. The page on why values differ explains choices like this one.

The 14 sun letters add up to 4050. The 14 moon letters add up to 1945. Together they make 5995, the sum of all 28 letters.

How Can You Tell Which Group a Word Belongs To?

You only need to look at the first letter after the alif and lam. Here is a simple routine for any word that starts with al-.

1. Find the first letter of the noun, after ال.
2. Check it against the moon line ابغ حجك وخف عقيمه.
3. If the letter is in the line, it is a moon letter and the lam is said.
4. If it is not in the line, it is a sun letter and the lam blends in.

Try الجبل (the mountain). Jim is in the moon line, so it is said al-jabal in standard Arabic.

Now try الزمن (time). Zay is not in the line, so it is said az-zaman.

Remember that the same word may sound different in a regional dialect. The rule here describes standard Arabic.

Where Did the Rule Come From?

One common account in language studies looks at very early Semitic languages. It says a noun could be made definite by doubling its first consonant, so “book” would become ak-kitab.

In that account, the lam in Arabic al- appeared later, through a process called dissimilation. The sun letters are the ones where the old doubling still shows.

Treat this as a scholarly theory, not a settled fact. Scholars still discuss how the article began, and nothing on this page depends on it.

Does Maltese Have Sun and Moon Letters Too?

Yes. Maltese has descended from Arabic and keeps the same idea, with its own spelling.

The sun is ix-xemx, with assimilation. The moon is il-qamar, without it.

Maltese writes the article as il- and has a few extra rules for words that start with vowels. That is why it is useful as a comparison, but it is outside the Arabic script lessons here.

What Happens to the Alif of al-?

The alif of al- is said only when the word stands at the start of a phrase. When another word comes before it, that alif is dropped in speech but stays in writing.

Teaching books mark this with a small sign above the alif. It is a separate idea from sun and moon letters, but the two often appear together in the same word.

So the full sound of a phrase depends on both rules. One looks at the word before, and the other looks at the letter after.

What Mistakes Do Learners Make?

• Reading the lam out loud before a sun letter. Say ash-shams, not al-shams.
• Dropping the lam in spelling. The lam is always written, so الشمس keeps it.
• Learning both lists by heart. It is easier to learn the 14 moon letters and treat the rest as sun letters.
• Mixing up this rule with joining rules. Which letters connect is a different topic, covered on the non-connecting letters page.
• Expecting every name to follow it. Latin spellings of names often skip the change.

Does This Matter for Urdu Readers?

Urdu borrows many Arabic names and phrases, and those words often carry al- with them. Readers often hear the sound change in names such as Abdur Rahman.

Spellings of such names vary from writer to writer. The Arabic form of the name is the one used for Abjad values here.

How Does the Rule Show Up in Names?

Many Arabic names contain al-. In the Arabic script it is always the same alif and lam. In Latin spelling, writers often follow the sound or the script, and they do not always agree.

The name عبد الرحمن is a good case. Ra is a sun letter, so it is often said Abdur Rahman.

It is also written Abdul Rahman. Both spellings stand for the same Arabic letters, which total 405.

Wikipedia notes that most modern Latin spellings of names ignore the assimilation rule. For more on spelling and value, see the Arabic names page and the Arabic alphabet in order.

Where Does This Fit in the Arabic Script Guide?

Sun and moon letters are about sound. The shapes and joining of letters are a separate topic. The Arabic script guide gathers both, and the letter count page explains why 28 is the usual number.

The figure used the alphabet order. The page on abjad and hijai order shows how it differs from the older abjad order.

Sources and Further Reading

• Sun and moon letters, Wikipedia. The two lists of 14, the rule, the jim and heavy letter notes, shadda and sukun, and the memory line.
• Sun letters, University of Oregon open textbook. The rule that the lam is silent and the next sound is doubled.
• Definite Article in Arabic, Madinah Arabic. The 14 and 14 split, the tongue tip description, and the point that the rule affects speech, not writing.
• Writing the Definite Article, Elon.io Arabic grammar. The spelling stays the same before sun letters, and the lists of both groups.
• Abjad values come from this site’s tested engine. See the methodology.

Frequently Asked Questions