Learn Hardcore Portuguese (Portugal): À noite, a lua ilumina a muralha e a lagoa. - At night, the moon lights up the city wall and the lagoon.

a (without accent, article) → a lua = the moon
a (without accent, preposition) → vou a casa = I go home
há (with h, verb) = there is / there are OR ago
- Há uma lua cheia. = There is a full moon.
- Há três dias. = Three days ago.

So:

à = at/to the (feminine)
a = the (fem.) or to
há = there is / are, or ago

Could I say De noite instead of À noite? Is there a difference?

Both À noite and De noite are correct and common, and both can translate as at night / in the evening. The difference is subtle and mostly about style and nuance:

À noite
- Slightly more neutral or a bit more formal.
- Very common in writing.
- Often used for a general, habitual time:
  - À noite, estudo português. = At night, I study Portuguese.
De noite
- Very common in speech, also correct in writing.
- Can sound a touch more colloquial in some contexts.
- Also used for general habits:
  - De noite, estudo português.

In many everyday contexts, you can use either without any real change in meaning. Learners can safely treat them as interchangeable for now.

Why is it a lua and not just lua? In English we usually say the moon, but sometimes with general nouns we drop the.

In European Portuguese, the definite article is used more often than in English, especially with:

Unique things:
- a lua = the moon
- o sol = the sun
General categories:
- Gosto de a lua. (normally contracted: Gosto da lua.)
- O cão é um animal fiel. = The dog is a faithful animal (dogs in general).

In this sentence:

a lua ilumina a muralha e a lagoa
literally: the moon illuminates the wall and the lagoon.

This is natural Portuguese when talking about the moon as a known, specific thing.
You almost always say a lua, not bare lua, except in titles, lists, and some poetic or very telegraphic styles.

Why are lua, muralha, and lagoa all feminine? Is it just because they end in -a?

In Portuguese, grammatical gender is mostly a property you have to learn with each noun, but some patterns help:

Nouns ending in -a are very often feminine:
- a lua (moon)
- a muralha (defensive wall, rampart)
- a lagoa (lagoon, small lake)

So in your sentence, all three nouns are feminine singular, so they use a as the article:

a lua
a muralha
a lagoa

There are exceptions (for example, o dia, o mapa), so the ending is a strong clue but not an absolute rule.

What exactly is a muralha? Is it just a wall?

Muralha is more specific than just wall:

parede = a wall of a room or building (indoor or structural wall)
muro = an outside wall, not usually for large-scale defense (a garden wall, wall around a house)
muralha = a large, thick defensive wall, like:
- city walls
- castle walls
- fortification walls

So a muralha is best thought of as the rampart / the city wall / the defensive wall, not just any random wall.

What verb form is ilumina? Which verb is it from?

Ilumina is from the verb iluminar (to illuminate, to light up).

In this sentence:

Subject: a lua (the moon)
Verb: ilumina
Tense: present indicative
Person: 3rd person singular (ele / ela / você)

Conjugation (present indicative):

eu ilumino
tu iluminas
ele / ela / você ilumina
nós iluminamos
vós iluminais (rare in modern speech)
eles / elas / vocês iluminam

So a lua ilumina… = the moon illuminates… / the moon lights up…. The present tense here expresses a habitual or general fact.

Why does the sentence start with À noite? Could I say A lua ilumina a muralha e a lagoa à noite instead?

Yes, both are correct:

À noite, a lua ilumina a muralha e a lagoa.
A lua ilumina a muralha e a lagoa à noite.

Differences:

Starting with À noite puts light emphasis on the time:
- It answers when first.
- Common in storytelling or descriptions to set the scene.
Putting à noite at the end is also natural and neutral; it often feels like a normal, straightforward sentence order.

In Portuguese, time expressions frequently appear at the beginning, but they can also go at the end without changing the basic meaning.

Why is the article a repeated before lagoa? Could I say a muralha e lagoa?

In standard, natural Portuguese you normally repeat the article:

a muralha e a lagoa = the wall and the lagoon

Not:

✗ a muralha e lagoa

Repeating the article is the default with two separate nouns:

o pai e a mãe = the father and the mother
o cão e o gato = the dog and the cat
a casa e o jardim = the house and the garden

You only drop the second article in some fixed expressions or when the nouns form a very tight unit (especially with the same gender and number), but a muralha e lagoa sounds incomplete or non‑standard. So: always say a muralha e a lagoa here.

Why is there a comma after À noite? Would it be wrong to omit it?

In European Portuguese, it is very common (and usually recommended) to use a comma after an initial adverbial expression like a time phrase:

À noite, a lua ilumina…
De manhã, tomo café.

This comma marks that À noite is an introductory element. It is similar to English:

At night, the moon lights up…

If you omit the comma:

À noite a lua ilumina a muralha e a lagoa.

It is not a serious error in informal writing, and many native speakers do omit such commas. However, in careful or formal writing, the comma is preferred and considered more correct.

How do you pronounce À noite and lua in European Portuguese?

Approximate European Portuguese pronunciation:

À noite → [a ˈnoj.tɨ]
- À: similar to a in English father, but shorter.
- noi: a diphthong like noi in English noise, but shorter, more rounded.
- Final -te: often sounds like t plus a very reduced vowel ɨ, almost like t alone for many speakers.
lua → [ˈlu.ɐ]
- lu: like loo in English loop, but shorter.
- Final -a in European Portuguese is usually pronounced as a very short, reduced vowel ɐ, not a full ah.

Putting it together more naturally:

À noite, a lua ilumina a muralha e a lagoa.
Rough, very simplified guide: “A NOY-t(ə), a LOO-ɐ i-lu-MEE-nɐ a mu-RAL-yɐ i a la-GO-ɐ.”

(Real European Portuguese reduces and connects sounds more than this, but this gives you a starting point.)

Does ilumina here mean something happening right now, or a general habit?

In Portuguese, the present indicative can express:

An action happening now:
- Ele ilumina a sala. = He is lighting up the room (right now).
A habitual or general truth:
- A lua ilumina a muralha e a lagoa.
  → The moon illuminates the wall and the lagoon (whenever it is night; this is a repeated or typical action).

In your sentence, it is naturally understood as a habitual / general situation: what usually happens at night, not just one specific night. The context (time expression À noite) pushes the interpretation towards a regular occurrence.