Learn Hardcore Japanese: hosi ga kumo de mienai yoru mo, sora ha sizuka desu. - Even on nights when stars can’t be seen because of clouds, the sky is quiet.

The particle が marks 星 as the grammatical subject of the clause 星が雲で見えない, focusing on the action “not being seen.” If you used は (星は), you’d be making 星 the topic and implying a contrast or general statement about stars, which changes the nuance. Here we simply state that “(the) stars aren’t visible” under certain conditions.

**What does 「雲で」 mean here? Is 「で」 an instrument?

In this sentence, で indicates cause or reason: “because of clouds” or “due to clouds.” It’s not an instrument (“with”), but explains why the stars can’t be seen. So 雲で見えない means “(they) cannot be seen because of clouds.”

**How does 「見えない夜」 work grammatically?

This is a relative clause. In Japanese, any phrase before a noun modifies it directly. So 星が雲で見えない (“stars aren’t visible because of clouds”) modifies 夜. Together 星が雲で見えない夜 means “nights when the stars aren’t visible.”

**What’s the role of 「も」 after 「夜」?

The particle も here means “even” or “also.” It emphasizes that even on those particular nights (when you can’t see the stars), the following applies. In English: “Even on nights when the stars aren’t visible…”

**Why is 「空」 marked with 「は」 in 「空は静かです」?

After setting up the condition (“even on those nights”) with も, the sentence shifts to a new topic: 空は. Here は marks 空 (“the sky”) as the topic, so we’re saying, “As for the sky, it is quiet.” This contrastive use emphasizes the “sky” despite the earlier mention of “nights.”

**Why is 「静か」 followed by 「です」? Isn’t that a noun?

静か is an na-adjective (形容動詞). To predicate it politely, you attach です. So 静かです means “is quiet.” Without です, it would sound abrupt or plain (静かだ).

**Could I rephrase 「星が雲で見えない夜も、空は静かです」 in another way?

Yes. A more casual version:
・星が雲に隠れて見えない夜でも、空は静かだ。
Here 雲に隠れて (“hidden by clouds”) adds a slight nuance, 夜でも can replace 夜も, and だ is the casual copula instead of です. The overall meaning remains the same.