Sidus caeleste lucet.

Because caeleste is the neuter nominative singular form of the adjective caelestis, caeleste.

It has to agree with sidus, which is:

• neuter
• singular
• nominative (the subject)

So:

• masculine/feminine nominative singular: caelestis
• neuter nominative singular: caeleste

Since sidus is neuter, Latin uses caeleste.

Here sidus is in the nominative singular, because it is the subject of the verb lucet.

So the basic structure is:

• sidus caeleste = the heavenly star / heavenly body
• lucet = shines

We know it is the subject because:

1. sidus is in the nominative case.
2. lucet is third person singular, so it needs a singular subject.
3. caeleste agrees with sidus, so together they form one noun phrase: the heavenly star.

Lucet is:

• third person singular
• present tense
• active voice
• indicative mood

It comes from the verb luceo, lucere, meaning to shine.

So lucet means he/she/it shines.
In this sentence, it means it shines, referring to sidus.

Latin usually has no article. That means it does not have separate words for the or a/an.

So sidus caeleste could mean:

• the heavenly star
• a heavenly star
• the heavenly body

The exact English translation depends on context.

In Latin, adjectives can come before or after the noun. Both are common.

So all of these are possible in principle:

• sidus caeleste
• caeleste sidus

The sentence you have uses sidus caeleste, with the adjective after the noun. That is completely normal Latin.

Yes. Latin word order is much more flexible than English word order because the endings show the grammar.

For example, these would express the same basic idea:

• Sidus caeleste lucet.
• Caeleste sidus lucet.
• Lucet sidus caeleste.

The differences are mostly about emphasis or style, not core meaning.

Here it is an adjective modifying sidus.

It means heavenly, celestial, or of the sky.
Because it matches sidus in gender, number, and case, we know it is describing that noun.

Sidus is neuter.

That matters because any adjective describing it must also be neuter. That is why Latin uses caeleste, not a masculine or feminine form.

A common Classical pronunciation would be approximately:

SEE-doos kai-LES-teh LOO-ket

More specifically:

• sidus = SEE-doos
• caeleste = kai-LES-teh
• lucet = LOO-ket

A few helpful points:

• c is always hard, like k
• ae sounds like ai in aisle
• u sounds like oo

Yes. The ending -et already tells you the verb is third person singular, so Latin could simply say lucet for it shines.

But Latin often still states the subject if it wants to name it clearly. Here:

• lucet = it shines
• sidus caeleste lucet = the heavenly star shines

Yes, sidus is a third-declension neuter noun. Its dictionary form is usually given as:

sidus, sideris n.

That tells you:

• nominative singular: sidus
• genitive singular: sideris
• gender: neuter

A learner may notice that the stem changes from sidus- to sider- in other forms. That is normal for many third-declension nouns.

Yes. Depending on context, caeleste can be translated as:

• heavenly
• celestial
• of the sky

So the full phrase could be understood in slightly different ways:

• the heavenly star
• the celestial body
• the star of the sky

The exact English wording depends on what nuance the translator wants.