O planeta parece azul.

O is the masculine singular definite article, meaning the.

• o planeta = the planet
• Portuguese uses definite articles more often than English does, so this is very normal.

Because planeta is treated as a masculine singular noun, it takes o.

Yes. While many nouns ending in -a are feminine, this is not a rule without exceptions.

Planeta is a masculine noun:

• o planeta
• um planeta

This is common with some words of Greek origin, such as:

• o planeta
• o problema
• o sistema
• o mapa

So learners should not rely only on the final letter.

Parece comes from the verb parecer, which usually means:

• to seem
• to appear
• sometimes to look

So O planeta parece azul means the planet seems/looks blue.

In this sentence, parece is in the third person singular present tense, matching o planeta.

Because parecer is the infinitive, meaning to seem.

In a normal sentence with a subject, you usually need a conjugated form:

• eu pareço = I seem
• você/ele/ela parece = you/he/she seems
• o planeta parece = the planet seems

So parece is used because the subject is o planeta, which is third person singular.

Yes, in many contexts it can.

For example:

• Ela parece cansada. = She looks tired.
• O planeta parece azul. = The planet looks blue.

But be careful: look in English has several meanings. Portuguese often uses different verbs depending on the idea:

• look/seem → parecer
• look at → olhar
• look for → procurar

So here parece is about appearance, not about directing your eyes.

Because azul is an adjective that can be used for both masculine and feminine singular nouns without changing form.

Examples:

• o planeta azul
• a camisa azul

Its plural does change:

• os planetas azuis
• as camisas azuis

So in O planeta parece azul, azul stays the same because the noun is singular.

In this sentence, azul is not directly modifying the noun inside the noun phrase. It is working as a predicate adjective after the verb parecer.

Structure:

• O planeta = subject
• parece = verb
• azul = adjective describing how it seems

This is similar to English:

• The planet seems blue

Compare:

• o planeta azul = the blue planet
• o planeta parece azul = the planet seems blue

These are different structures.

Yes, but the meaning is slightly different.

• O planeta é azul. = The planet is blue.
  This sounds more definite, like a fact.

• O planeta parece azul. = The planet seems blue / looks blue.
  This suggests appearance, impression, or uncertainty.

So both are correct, but they do not mean exactly the same thing.

A simple approximate pronunciation is:

oo pla-NE-ta pa-RE-si a-ZOOL

A few notes:

• o often sounds like oo in Brazilian Portuguese when unstressed
• planeta has stress on ne
• parece has stress on re
• azul has stress on the last syllable: zul

A rough IPA version in Brazilian Portuguese is: u plaˈnɛtɐ paˈɾes(i) aˈzuw

Pronunciation varies a bit by region.

No. Portuguese often leaves out subject pronouns when the subject is already stated or clear.

Here, o planeta is the subject, so there is no need for ele:

• O planeta parece azul.

You could say Ele parece azul if the context already makes clear that ele refers to the planet, but it is not necessary here.

The normal, neutral order is:

O planeta parece azul.

That is the most natural order for a basic statement in Portuguese:

• subject + verb + adjective/complement

You might see other word orders in poetry, emphasis, or special contexts, but for learners, this is the standard pattern to use.

In this sentence, azul is definitely an adjective.

• O planeta parece azul. = The planet seems blue.

Portuguese color words are usually used as adjectives when they describe nouns. In some contexts, color words can behave more like nouns, but for a beginner, it is best to think of azul here as an adjective meaning blue.

Yes, it is grammatical and natural.

A Brazilian might say it in contexts like:

• talking about a planet seen in an image
• describing Earth from space
• commenting on appearance under certain light

Depending on context, they might also say:

• O planeta está azul. if it appears blue at the moment
• O planeta é azul. if stating it as a characteristic
• O planeta parece ser azul. if sounding a bit more formal or cautious

But O planeta parece azul is perfectly fine.