Learn Hardcore Polish: Podczas wschodu słońca gwiazdy powoli znikają, a niebo robi się niebieskie. - During the sunrise the stars slowly disappear, and the sky becomes blue.

Podczas means “during” and is followed by a noun phrase in the genitive case, e.g. podczas wschodu słońca – during sunrise.
Kiedy and gdy mean “when” and are followed by a full clause with a verb, e.g. Kiedy słońce wschodzi, gwiazdy znikają – When the sun rises, the stars disappear.

So:

Podczas + noun → Podczas wschodu słońca
Kiedy/gdy + verb → Kiedy słońce wschodzi

Why is it podczas wschodu słońca, not podczas wschód słońca?

Podczas always takes the genitive case.

wschód is nominative (dictionary form)
its genitive is wschodu

Similarly:

słońce → genitive słońca

So wschód słońca (sunrise) in the genitive becomes wschodu słońca after podczas. Saying podczas wschód słońca would be ungrammatical.

Why is wschodu singular? Could we say something like podczas wschodów słońca?

In this sentence we’re talking about a typical event: (during) sunrise in general, so Polish uses the singular noun wschodu słońca.

Wschody słońca is the plural (sunrises) and it’s used when you count or compare different sunrises, e.g.

Lubię oglądać wschody słońca – I like watching sunrises.

You could say podczas wschodów słońca, but that would sound like you’re talking about many separate sunrises in a more abstract or statistical way. For a general descriptive sentence, singular is natural.

What case is gwiazdy in, and why that form?

Gwiazdy here is nominative plural of gwiazda (a star).

Subject: gwiazdy (stars)
Verb: znikają (disappear)

So gwiazdy must be nominative, because it’s the doer of the action.
The genitive plural would be gwiazd, but that form is used after certain prepositions or in other roles, not as the subject here.

What does powoli mean, and where can it go in the sentence?

Powoli means “slowly” or “gradually”. It’s an adverb describing how the stars disappear.

In this sentence it’s placed just before the verb:

gwiazdy powoli znikają

You could also say:

gwiazdy znikają powoli

Both are correct. The usual, neutral position is before the verb, but adverbs like powoli are fairly flexible in Polish.

Why is the verb znikają and not something like znikną?

Znikają is present tense, imperfective aspect, 3rd person plural of znikać (to disappear, be in the process of disappearing). It suggests a gradual, ongoing process – which fits with powoli (slowly).

Znikną is future tense, perfective: it focuses on the result (“they will disappear (completely)”).
Here the idea is that during sunrise they are slowly disappearing, not just the end result, so znikają is the natural choice.

Why is the conjunction a used, not i? Aren’t both just “and”?

Both a and i can translate as “and”, but they have different nuances:

i: neutral “and”, usually just adding information.
a: often shows a contrast or a different perspective/side-by-side picture.

In gwiazdy powoli znikają, a niebo robi się niebieskie, a suggests a contrast:

on one hand, the stars are disappearing,
on the other hand, the sky is becoming blue.

You could use i here, but a paints the two simultaneous, contrasting changes more vividly and is more idiomatic.

Why is there a comma before a in Polish, when in English we wouldn’t usually put a comma before “and” here?

Polish comma rules are stricter than English ones.

In Polish, when you have two independent clauses joined by a conjunction like a, i, ale, lecz, you normally put a comma before the conjunction:

gwiazdy powoli znikają, a niebo robi się niebieskie

Each part has its own subject and verb, so they are two separate clauses; hence the comma. In English, the comma is optional or often omitted in such short sentences, but in Polish it’s standard.

What exactly does niebo robi się niebieskie mean literally?

Literally it is “the sky is making itself blue”, but idiomatically it means “the sky is becoming/turning blue.”

niebo – the sky (subject)
robi się – “makes itself” → becomes (reflexive construction)
niebieskie – blue (adjective)

This robić się + adjective pattern is a very common way in Polish to say that something changes state:

robi się ciemno – it’s getting dark
robi się zimno – it’s getting cold

Could we say niebo staje się niebieskie instead? Is there a difference?

Yes, niebo staje się niebieskie is correct and also means “the sky becomes blue.”

Nuance:

robi się is very colloquial and everyday, very common in spoken Polish.
staje się is a bit more formal or neutral, more common in writing or slightly higher register.

In normal description of nature like this sentence, both are fine. Robi się just feels more conversational.

Why is the adjective niebieskie, not niebieski or niebieska?

Adjectives in Polish must agree with the noun in gender, number, and case.

niebo is neuter, singular, nominative.
The nominative singular neuter ending for adjectives is -e, so niebieski → niebieskie.

Compare:

niebieski samochód (masc.)
niebieska książka (fem.)
niebieskie niebo (neut.)

Why is się after robi and not in another position, like niebo się robi niebieskie?

Polish się is a clitic – a little word that tends to stay right after the verb. The standard position is:

robi się

You can sometimes hear niebo się robi niebieskie, and it will be understood, but ciernik + się (verb + się) is much more common and feels more natural:

niebo robi się niebieskie is the default, idiomatic order.

Can the word order in the whole sentence be changed, for example: Gwiazdy powoli znikają podczas wschodu słońca, a niebo robi się niebieskie?

Yes, that word order is also grammatical:

Gwiazdy powoli znikają podczas wschodu słońca, a niebo robi się niebieskie.

Polish word order is fairly flexible, especially for adverbials like podczas wschodu słońca.

Differences:

Podczas wschodu słońca gwiazdy powoli znikają… – fronted time phrase; strong “During sunrise…” setting at the beginning.
Gwiazdy powoli znikają podczas wschodu słońca… – starts with “The stars slowly disappear…”, adding when this happens at the end.

Both are natural; the choice is mostly about emphasis and style.

How do you pronounce the consonant cluster wsch in wschodu? It looks hard.

In wschodu, the cluster wsch is pronounced as [fsx] roughly:

w → like f in fine (before s it devoices)
sz (spelled sz, but here as part of wsch) → like sh in ship
ch → a voiceless kh sound, like German Bach

So wschodu sounds approximately like “f-s-hod-oo”, with fs flowing into a single cluster: F-SH-khO-doo (using English approximations).

At normal speed, Poles say it smoothly, but it’s normal for learners to slow down at first: w–sch–o–du.