Í kvöld er himinninn svo skýr að við sjáum tunglið vel út um gluggann.

Í kvöld means tonight or this evening.

It is a very common time expression in Icelandic. Even though í often means in, the whole phrase is best understood as one unit meaning tonight.

This is because Icelandic follows a verb-second pattern in main clauses.

That means:

• the first element can be a time phrase, place phrase, object, etc.
• but the finite verb usually comes next

So:

• Í kvöld = first element
• er = finite verb in second position
• himinninn = subject

A more basic order would be:

• Himinninn er svo skýr í kvöld...

But when Icelandic puts Í kvöld first for emphasis or style, the verb still stays second:

• Í kvöld er himinninn svo skýr...

Because himinninn means the sky, while himinn means sky.

Icelandic usually puts the definite article onto the end of the noun instead of using a separate word like English the.

So:

• himinn = sky
• himinninn = the sky

This is one of the most important features of Icelandic nouns.

Because the base noun already ends in -nn, and then the definite ending is added.

So you get:

• himinn = sky
• himinn + inn → himinninn = the sky

It can look strange at first, but it is a normal result of adding the suffixed definite article.

Skýr is the adjective clear.

Here it is a predicate adjective after er and it agrees with himinninn.

Since himinninn is:

• masculine
• singular
• nominative

the adjective appears as:

• skýr

So:

• himinninn er skýr = the sky is clear

Even when an adjective comes after to be, Icelandic still makes it agree with the noun.

Svo ... að means so ... that.

In this sentence:

• svo skýr = so clear
• að við sjáum tunglið vel = that we see the moon well

So the structure is:

• himinninn er svo skýr að...
• the sky is so clear that...

This is a very common Icelandic pattern.

Here að means that, not to.

Icelandic að can have more than one job:

• að = to before an infinitive
• að = that as a conjunction

In this sentence it introduces a subordinate clause:

• að við sjáum tunglið vel
• that we see the moon well

So this is the conjunction að, not the infinitive marker.

Við means we, and sjáum is the present tense form of sjá, meaning see.

So:

• við sjáum = we see

The subordinate clause after að has a more straightforward subject-verb order here:

• að við sjáum tunglið vel

Also, Icelandic usually keeps the subject pronoun in normal speech and writing, even though the verb ending already gives person and number.

Tunglið means the moon.

The base noun is:

• tungl = moon

With the definite article added:

• tunglið = the moon

This noun is neuter, and in this sentence it is the direct object of sjáum. The accusative and nominative singular forms are the same here, so you see tunglið.

Because vel is an adverb, and it modifies the verb sjáum.

So:

• vel = well
• sjá vel = see well

You need an adverb here because the sentence is describing how we see the moon, not describing the moon itself.

In natural English, this is often translated as:

• we can see the moon clearly
• we see the moon well

It means out through the window or more naturally in English, out the window.

The parts are:

• út = out
• um = through / via
• gluggann = the window

Together, út um gluggann describes seeing something by looking outward through the window opening.

So:

• sjá tunglið vel út um gluggann = see the moon well out the window

The base noun is:

• gluggi = window

Here it appears as gluggann because:

• it is definite: the window
• it follows um, which takes the accusative

So:

• gluggi = window
• glugginn = the window, nominative
• gluggann = the window, accusative

This is a good example of how Icelandic noun endings change for both case and definiteness.

Because English often uses can see where Icelandic simply uses the ordinary verb see.

So Icelandic:

• við sjáum tunglið vel

can naturally mean:

• we see the moon well
• we can see the moon clearly

The idea of ability or possibility is understood from the context: the sky is so clear that seeing the moon is possible.

If Icelandic wanted to stress ability more explicitly, it could use geta:

• við getum séð tunglið
• we can see the moon

But in this sentence, that extra verb is not necessary.