The Dutch phrase "zon onder 11 september 2025" functions as a noun phrase. It designates a specific event: the sunset on September 11, 2025. Although it contains components from different grammatical categories"zon" (sun) is a noun, "onder" (under/down) is an adverbial particle, and the date is an adverbial of timethe entire construction operates as a single nominal unit that can act as the subject or object in a sentence.
This structure is derived from the Dutch separable verb "ondergaan," which means "to go down" or "to set." The full clause would be "De zon gaat onder op 11 september 2025" (The sun goes down on September 11, 2025). The keyword is an elliptical or condensed form of this clause, a common linguistic phenomenon where the verb ("gaat") is omitted, leaving the subject ("zon") and the verbal particle ("onder") to represent the entire action. This process of nominalization effectively transforms the description of an action into the name of an event.
Therefore, for the purpose of an article, treating the keyword as a noun is the correct analytical step. This establishes the topic not as an ongoing action, but as a distinct, definable phenomenon. It allows the article to focus on the specific attributes of this event, such as the precise time of sunset, the astronomical coordinates, visibility conditions, and its cultural or scientific significance for that particular date.
