La stella esplode nello spazio.

Italian often uses the definite article where English might not, especially when talking about a specific noun or about something as a class.

• la stella = the star
• stella by itself can appear in some contexts, but in a normal full sentence like this, the article is usually expected.

Also, stella is a feminine singular noun, so its article is la.

You usually learn the gender together with the noun:

• la stella = feminine
• plural: le stelle

Many Italian nouns ending in -a are feminine, so stella fits that common pattern. As always, it is best to memorize nouns with their article.

Esplodere is the infinitive, meaning to explode.
In the sentence, the verb has to be conjugated to match the subject:

• esplodere = to explode
• esplode = it explodes / is exploding

Since la stella is third-person singular (the star / it), the correct present-tense form is esplode.

It is the present indicative.

So La stella esplode nello spazio can mean:

• The star explodes in space
• sometimes, depending on context, The star is exploding in space

Italian present tense often covers both the simple present and, in some cases, the English present progressive.

This is because nello is a combined form of:

• in + lo = nello

And lo is the masculine singular article used before certain sounds, including:

• s + consonant: spazio, studente, sport
• z: zaino
• ps, gn, x, and a few others

Since spazio begins with sp-, the correct article is lo, so:

• il libro
• but lo spazio

Therefore:

• in + lo spazio = nello spazio

Because of its initial sound.

Italian uses lo before masculine singular nouns starting with:

• s + consonant → lo spazio
• z → lo zaino
• ps → lo psicologo
• gn → lo gnomo
• x → lo xilofono

So:

• not il spazio
• but lo spazio

This is one of the most important article patterns to remember.

Nello is a contracted preposition (in Italian, a preposizione articolata).

It comes from:

• in
  • lo = nello

Italian very often combines a preposition with a definite article:

• in + il = nel
• in + lo = nello
• in + la = nella
• in + i = nei
• in + gli = negli
• in + le = nelle

So nello spazio literally corresponds to in the space / in space, depending on context.

Italian and English do not always use articles in the same way.

English often says:

• in space

But Italian commonly says:

• nello spazio

Even when English omits the article, Italian may still use one. So this is something you often have to learn as part of the expression rather than translate word-for-word.

No, it is very standard Italian word order:

• La stella = subject
• esplode = verb
• nello spazio = prepositional phrase

So it follows a normal subject + verb + complement pattern, much like English:

• The star explodes in space

A helpful approximation is:

• eh-SPLOH-deh

A few points:

• the e sounds are pure vowels, not like the English ay
• spl is pronounced clearly as a cluster
• the stress is on -plo-: esPLOde

And spazio is roughly:

• SPA-tsyoh

with zi sounding like tsy.

Yes. That would mean:

• The star is exploding in space

This form uses:

• stare
  • gerund
• sta esplodendo

Compare:

• La stella esplode nello spazio = the star explodes / is exploding
• La stella sta esplodendo nello spazio = the star is exploding

The second one makes the ongoing action more explicit.

The plural would be:

• Le stelle esplodono nello spazio.

Changes:

• la stella → le stelle
• esplode → esplodono

So:

• singular: La stella esplode nello spazio.
• plural: Le stelle esplodono nello spazio.