Learn Hardcore Portuguese (Brazil): Quando eu era criança, costumava olhar as estrelas sentado no jardim. - When I was a child, I used to look at the stars sitting in the garden.

Fui criança is grammatically possible but sounds strange here; it would emphasize a completed, bounded fact (“I was a child (once)”), which clashes with the idea of a whole childhood as a period during which a habit existed.

What exactly does “costumava” mean here?

Costumava is the imperfect of costumar, and costumar + infinitive means:

to usually do something
to be in the habit of doing something
English “used to …” (for habits)

So costumava olhar ≈ “I used to look” / “I would look (habitually)” at the stars.
It expresses a repeated, habitual action in the past, not just something that happened once.

Could we just say “olhava as estrelas” instead of “costumava olhar as estrelas”?

Yes, you could say:

Quando eu era criança, olhava as estrelas sentado no jardim.

This is also correct. The difference is nuance:

costumava olhar: explicitly says it was a habit.
olhava (imperfect alone): usually also understood as a repeated/ongoing action, but without highlighting the idea of “habit” as strongly.

Both work; costumava just makes the “usual habit” meaning very clear.

Why are both verbs in the imperfect: “eu era criança, costumava olhar”?

Because both parts describe:

a background state (era criança – “I was a child”)
a repeated habit during that period (costumava olhar – “I used to look at the stars”)

The imperfect tense is used for:

background descriptions (age, weather, situations)
habits and routines in the past

So era and costumava match each other perfectly in aspect: they both portray the past as ongoing / habitual, not as a series of completed events.

Why is there a comma after “criança”?

The clause “Quando eu era criança” is a time clause introducing the context:

Quando eu era criança, costumava olhar…

In Portuguese, an introductory clause like this is normally followed by a comma, especially when it comes before the main clause.

If you reverse the order, you usually don’t use a comma:

Costumava olhar as estrelas sentado no jardim quando eu era criança.

Why is it “olhar as estrelas” and not “olhar para as estrelas”?

Both are possible, but there is a nuance:

olhar as estrelas
– more direct; literally “look the stars,” understood as “look at the stars.”
– very common, especially in descriptions like this.
olhar para as estrelas
– more explicit, literally “look to/at the stars.”
– often a bit more concrete/physical or slightly more emphatic: where the gaze is directed.

In everyday speech, you’ll hear both. In this sentence, olhar as estrelas sounds very natural and slightly more fluent/compact.

What is the difference between olhar, ver, and assistir here?

olhar = to look (at), to direct your eyes intentionally
– olhar as estrelas = “to look at the stars” (on purpose)
ver = to see, to perceive with your eyes (may be more passive)
– ver as estrelas = “to see the stars” (they are visible)
assistir (a) = to watch, to attend (a show, movie, match, etc.)
– You don’t use assistir with estrelas in this sense.

So olhar as estrelas is best here because it suggests the intentional action of stargazing, not just passively seeing them.

Grammatically, what is “sentado” and why is it in the masculine singular?

Sentado is the past participle (or an adjective) of sentar (“to sit (down)”).

Here, it works like an adjective meaning “sitting / seated” and agrees with eu:

eu → masculine singular (by default, if gender is unknown)
so: sentado (masc. sg.)

If the speaker is:

a woman: she would normally write/say sentada
– Quando eu era criança, costumava olhar as estrelas sentada no jardim.
talking about “we” (mixed or male group): sentados
talking about a group of girls/women: sentadas

Why can we say “sentado no jardim” without a verb like “estava”?

In Portuguese, you can often omit estar when using an adjective/participle to give extra information about the subject.

So instead of:

Quando eu era criança, costumava olhar as estrelas enquanto estava sentado no jardim.

you can shorten this to:

Quando eu era criança, costumava olhar as estrelas sentado no jardim.

Here, sentado no jardim functions like a free modifier, implicitly meaning “while (I was) sitting in the garden.”
This structure is very common and natural in Portuguese.

Could we move “sentado no jardim” to another position in the sentence?

Yes. Portuguese word order is flexible for these “extra information” parts. For example:

Quando eu era criança, sentado no jardim, costumava olhar as estrelas.
Quando eu era criança, costumava, sentado no jardim, olhar as estrelas.

All are grammatical, but:

The original “…olhar as estrelas sentado no jardim” is the most natural and fluid.
Splitting the phrase with commas makes sentado no jardim more clearly a side comment, a bit more literary or formal.

Can we drop “eu” and say “Quando era criança, costumava olhar as estrelas…”?

Yes, and that’s very natural in Portuguese:

Quando era criança, costumava olhar as estrelas sentado no jardim.

Subject pronouns (like eu, ele, nós) are often omitted because the verb ending already shows who the subject is.

So:

with eu: era, costumava
with ele / ela / você: era, costumava (same forms!)

This means context is important. In an isolated sentence, keeping eu makes it immediately clear that “I” is the subject. In a longer text, once context is clear, people often drop eu.

Could we also say “Quando eu era criança, eu costumava olhar…” with the second “eu”?

Yes, that’s grammatically correct:

Quando eu era criança, eu costumava olhar as estrelas…

The second eu adds a bit of emphasis on the subject and is common in speech, especially if you want to stress contrast (e.g., “When I was a child, I used to look at the stars, but my brother didn’t”).

Without special emphasis, many speakers simply skip the second eu because the verb form already tells you it’s “I”.

Why is it “no jardim” and not “no quintal” or simply “no jardim de casa”?

All are possible, but they have slightly different usual uses:

no jardim = “in the garden”
– often suggests a more garden-like, planted area (flowers, lawn, etc.).
no quintal = “in the backyard”
– in Brazil, quintal is very common for the outdoor area behind/around the house, not necessarily a cultivated garden.
no jardim de casa = “in the garden at home” / “in our garden”
– more explicit, emphasizes it’s the garden belonging to one’s home.

The original is neutral and natural; the learner can choose jardim or quintal depending on the image they want.

Why is it “sentado” and not “sentando”?

Because Portuguese does not use the gerúndio (‑ndo form) the same way English uses -ing adjectives.

sentando = “sitting (down)” as an ongoing action, e.g.
– Ele estava se sentando. = “He was sitting down.”
sentado = “sitting, seated” as a state/position, like an adjective.

In your sentence, we describe how/where he was while looking at the stars, not the action of starting to sit. So we use the state:

sentado no jardim = “(being) seated / sitting in the garden.”

Is “costumava olhar as estrelas” very common in speech, or would Brazilians say something else more naturally?

Costumar + infinitive is common and natural in speech, especially to talk explicitly about habits.

However, you’ll also hear other very natural alternatives, for example:

Quando eu era criança, vivia olhando as estrelas sentado no jardim.
(vivia + gerúndio ≈ “was always doing / kept doing”)
Quando eu era criança, ficava olhando as estrelas sentado no jardim.
(ficava + gerúndio gives a sense of staying in that activity)
Quando eu era criança, olhava as estrelas sentado no jardim.
(imperfect alone; context usually shows it’s a habit)

The original with costumava is perfectly idiomatic and clear, especially for learners.

Why do we need the article “as” in “olhar as estrelas”? Could we just say “olhar estrelas”?

In Portuguese, nouns usually take a definite article (o, a, os, as) much more often than in English.

olhar as estrelas ≈ “to look at the stars” (the stars in the sky in general)
– very natural and idiomatic.

You can say olhar estrelas, but:

without the article, it sounds a bit more generic/indefinite, and in this specific everyday image (“looking at the stars in the sky”), Brazilians usually say as estrelas.

So olhar as estrelas is the most natural default choice here.

Is “costumava olhar para as estrelas” also correct, and does it change the meaning?

Yes, it’s correct:

Quando eu era criança, costumava olhar para as estrelas sentado no jardim.

Meaning:

basically the same: “I used to look at the stars.”
para just makes the direction of the gaze more explicit.

Nuance:

olhar as estrelas → smoother, slightly more idiomatic in many contexts.
olhar para as estrelas → a bit more concrete about “where you are looking.”

In normal conversation, both versions are fine.