Learn Hardcore Norwegian: Det blå lyset i bakgrunnen gjør scenen vakker. - The blue light in the background makes the stage beautiful.

Because the noun phrase is definite (we have det + adjective + definite noun). In the definite form, adjectives take the weak declension. Many weak forms add -e, but when an adjective already ends in a vowel (like blå), it remains unchanged. Hence det blå lyset, not det blått lyset.

What role does det play before blå lyset?

Here det is the neuter singular definite article used with an adjective. In Norwegian, when a definite noun has a preceding adjective, you use a separate article (det for neuter) instead of a suffix. It is not a pronoun but marks the phrase as definite.

Why does lyset end with -et?

The noun lys is neuter. Its definite singular is formed by adding -et, so lys → lyset.

Why do we say i bakgrunnen instead of just bakgrunn?

We need the preposition i to mean “in,” and bakgrunnen is in the definite form (“the background”) because we’re referring to a specific, known background. Saying simply bakgrunn without i or without the definite form would not convey “in the background.”

Why is vakker not inflected with -e, as in vakre?

In Norwegian, predicative adjectives (those that follow a verb and describe the result or state) remain in their base form. Since vakker follows gjør as an object complement, it stays uninflected.

What is the function of gjør here, and how is it different from er?

gjør means “makes” (causes to become) and introduces a result: gjør scenen vakker = “makes the scene beautiful.” If you used er, you’d simply state a condition (“is beautiful”) without highlighting that the light actively creates the beauty.

Why is the word order Det blå lyset i bakgrunnen gjør scenen vakker?

Norwegian main clauses follow the V2 rule: the finite verb must be the second constituent. Here the subject (Det blå lyset i bakgrunnen) comes first, then the verb (gjør), followed by object (scenen) and adjective complement (vakker).

Can I rephrase the sentence without gjør, and what happens to the meaning?

Yes. You can say Det blå lyset i bakgrunnen er vakkert. That simply describes the light itself as beautiful. You lose the nuance that the light is actively making the scene beautiful.