El científico estudia el universo.

El is the masculine singular definite article, equivalent to the.

So:

• el científico = the scientist
• el universo = the universe

Spanish uses articles very regularly. A singular countable noun like científico usually needs a determiner such as el, un, este, etc. Spanish also keeps the article in places where English sometimes would not.

Normally, no. In standard Spanish, a singular count noun used as the subject usually needs a determiner.

Natural options would be:

• El científico estudia el universo.
• Un científico estudia el universo.
• Este científico estudia el universo.

So Científico estudia el universo sounds incomplete to a native speaker.

Yes. In this sentence, el científico is masculine singular.

The feminine form is:

• la científica

Useful forms:

• el científico = masculine singular
• la científica = feminine singular
• los científicos = masculine plural or mixed group
• las científicas = feminine plural

The accent mark stays in both científico and científica.

The accent mark shows where the stress goes: cien-TÍ-fi-co.

Without the written accent, Spanish spelling rules would make you stress it differently. So the accent is needed to show the correct pronunciation.

It also helps learners notice that this is a four-syllable word with the stress on tí:

• cien
• tí
• fi
• co

In most of Spain, the first c in ci- is pronounced like th in think, not like s.

A rough guide is:

• thyen-TEE-fi-ko

More exactly:

• ci sounds roughly like thye
• stress is on tí
• the second c in -co sounds like k

So in most of Spain, científico does not start with an s sound.

Because estudia is the third-person singular present form of estudiar.

The subject is el científico, which is third-person singular, so the verb must match it.

Present-tense forms of estudiar:

• yo estudio
• tú estudias
• él/ella/usted estudia
• nosotros estudiamos
• vosotros estudiáis
• ellos/ellas/ustedes estudian

So el científico estudia is correct agreement.

Because Spanish often leaves subject pronouns out when they are not needed.

The verb ending already tells you the person and number:

• estudia = he/she/it studies

So El científico estudia... is completely normal. Adding él would usually be unnecessary unless you want emphasis or contrast.

Most basically, estudia is the present tense and is often translated as studies.

Depending on context, Spanish present tense can sometimes also refer to what someone is doing now, but if you want to clearly say is studying right now, Spanish often uses:

• está estudiando

So in an isolated beginner sentence like this, studies is the safest reading.

Because the personal a is mainly used before direct objects that are people, pets, or personified beings.

Examples:

• Veo al científico.
• Conozco a María.

But el universo is not a person, so there is no personal a:

• El científico estudia el universo.

El universo is used because the universe is understood as a unique, specific thing.

Compare:

• el universo = the universe
• un universo = a universe, one universe among others

In normal everyday meaning, we usually speak about the one known universe, so el is the natural choice.

The normal beginner-friendly order is subject + verb + object:

• El científico
  • estudia
    • el universo

Spanish word order is more flexible than English, so other orders are possible for emphasis or style, but this basic order is the most neutral and natural one to learn first.

So yes, word order can change, but this version is the standard default.

Here it is a noun, meaning scientist.

But científico can also be an adjective, meaning scientific.

For example:

• El científico estudia el universo. → noun
• el método científico → adjective

In your sentence, it is a noun because it comes after el and names a person.

No. In normal Spanish, they are not capitalized here.

Only El is capitalized because it is the first word of the sentence.

So:

• El científico estudia el universo.

That is the correct standard capitalization.