Learn Hardcore Norwegian: En stor overraskelse kan dukke opp en dag.

In Norwegian Bokmål, en is the indefinite article for singular common-gender nouns. Overraskelse (surprise) is a common-gender noun, so you say en overraskelse to mean “a surprise.” When you add the adjective stor (big), the article stays the same, giving en stor overraskelse (“a big surprise”).

Why doesn’t stor change form like in English comparatives or superlatives?

Norwegian adjectives agree in gender and number, but the basic form for common-gender singular is just stor. There’s no extra ending unless the noun is neuter (then you’d add -t, e.g. et stort hus) or plural (then you’d add -e, e.g. store overraskelser). Comparatives and superlatives are formed with større and størst, not by changing stor in this sentence.

What does dukke opp mean, and why is it written as two words?

Dukke opp is a phrasal (separable) verb meaning “to appear,” “to show up,” or “to pop up.” In the infinitive you write it as two words (dukke + opp). The particle opp modifies dukke (literally “to duck/sink”), turning it into “pop up.”

Why isn’t there an å before dukke opp, as in other infinitives?

When you use a modal verb like kan (can/may) in Norwegian, you drop the å before the main verb. So instead of kan å dukke opp, you simply say kan dukke opp.

What does en dag mean in this sentence?

Here en dag means “one day” in the sense of “someday” or “at some point in the future,” not “in one 24-hour period.” It’s an indefinite time adverbial, indicating that the surprise could show up at an unspecified future moment.

How is en dag different from om en dag?

en dag alone = “someday” or “one day” in an indefinite, vague sense:
En dag blir du lykkelig. (One day you’ll be happy.)
om en dag = “in a day’s time” or “after one day,” a precise time span:
Om en dag får du svar. (You’ll get an answer in one day.)

Why is en dag placed at the end, and can we move it elsewhere?

The default main-clause word order is Subject–Verb–Object/Other, so time adverbials like en dag often come after the verb phrase. If you put en dag at the beginning for emphasis, you must invert the subject and verb:
En dag kan en stor overraskelse dukke opp.

Why use dukke opp instead of skje (“to happen”) here?

While skje does mean “to happen,” dukke opp emphasizes the sudden, unexpected appearance of something. If you said en stor overraskelse kan skje en dag, it’s grammatically correct but feels more neutral. Dukke opp gives the idea of something popping into view or into your life.