Learn Hardcore Indonesian: Andaikan cuaca cerah malam ini, saya ingin kembali ke planetarium untuk melihat rasi baru. - If only the weather were clear tonight, I would like to go back to the planetarium to see a new constellation.

kalau – very common, neutral “if/when”, used in everyday speech.
- Kalau cuaca cerah malam ini, saya ingin…
jika – more formal/neutral “if”, common in writing, news, instructions.
- Jika cuaca cerah malam ini, saya ingin…
seandainya – close in feeling to “if only / if it were the case that”, often a bit emotional or regretful, but can also just be hypothetical.
- Seandainya cuaca cerah malam ini, saya ingin…
andaikan – like “suppose / imagine if” or “if only”; clearly hypothetical, sometimes slightly literary or “story-like.”
- Andaikan cuaca cerah malam ini, saya ingin…

You could replace andaikan here with kalau or jika and the sentence would still be correct; it would just feel more neutral and a bit less “imaginative.”

Why is there no word for “is” in cuaca cerah? Why not cuaca adalah cerah?

In Indonesian, you normally do not use a verb like “to be” (adalah) between a noun and an adjective in simple present descriptions.

Pattern:

[subject] + [adjective]
- cuaca cerah = “the weather (is) clear”
- dia pintar = “he/she (is) smart”
- mobil itu mahal = “that car (is) expensive”

Adalah is mainly used:

Between a subject and a noun phrase, not an adjective:
- Dia adalah dokter. = “He/She is a doctor.”
In more formal or written language, especially for definitions or explanations:
- Bahasa Indonesia adalah bahasa resmi Indonesia.

So cuaca cerah is the normal, natural way to say “the weather is clear.”
Cuaca adalah cerah sounds unnatural in everyday Indonesian.

Can I change the word order and say Malam ini cuaca cerah instead of cuaca cerah malam ini? Is there any difference?

Yes, you can say either:

Cuaca cerah malam ini.
Malam ini cuaca cerah.

Both are grammatical and mean essentially “The weather is clear tonight.”

Subtle nuance:

Cuaca cerah malam ini.
Slightly more focused on “the weather” as the topic, then adding “tonight” as extra information.
Malam ini cuaca cerah.
Slightly more focused on “tonight” first (“As for tonight, the weather is clear”).

In practice, both are fine; the difference is very small and usually context-dependent.

What is the difference between malam ini and nanti malam?

Both often translate as “tonight”, but they have different nuances:

malam ini – literally “this night”
- Neutral “tonight,” covering tonight as a time period (e.g. for plans, schedules).
- Can be used whether it is already night or still daytime.
nanti malam – literally “later tonight / tonight later”
- Emphasizes “later (this evening)” from the current moment.
- Common when it’s still earlier in the day and you’re talking about something that will happen later that night.

Examples:

In the morning or afternoon:
- Malam ini saya mau nonton film. = I’ll watch a movie tonight.
- Nanti malam saya mau nonton film. = I’ll watch a movie later tonight.
If it is already night, people usually say malam ini. Nanti malam can still be used, but then it feels like “later tonight (a bit later than now).”

In your sentence, malam ini is perfectly natural.

What’s the nuance of ingin compared to mau or akan here?

In the sentence:

saya ingin kembali ke planetarium…

ingin means “want / would like to” in a slightly more polite or neutral way than mau.

Differences:

ingin – “want / would like”; polite, good in both spoken and written language.
- Saya ingin makan. = I want / would like to eat.
mau – “want / going to”; very common in everyday speech, a bit more casual.
- Saya mau makan. = I want to eat / I’m going to eat.
akan – more of a future marker (“will”), not “want.”
- Saya akan kembali ke planetarium. = I will return to the planetarium.

You could say:

Saya mau kembali ke planetarium… – more casual.
Saya akan kembali ke planetarium… – more like stating a plan or intention (“I will go back”), not emphasizing desire.

Ingin is a good, neutral choice for textbooks and polite conversation.

Why use kembali ke planetarium and not something like pergi ke planetarium lagi or balik ke planetarium?

These options are all possible, but each has a nuance:

kembali ke planetarium
- kembali = “to return, to go back.”
- Slightly more neutral/formal, often used in writing or careful speech.
- Focus on the idea of returning to a place you have been before.
balik ke planetarium
- balik is more colloquial than kembali, very common in speech.
- Similar meaning to “go back.”
- Saya mau balik ke planetarium. (very natural in casual talk)
pergi ke planetarium lagi
- pergi = “to go,” lagi = “again.”
- Literally: “go to the planetarium again.”
- Emphasizes repetition (“again”) more than the sense of “returning.”

So:

If you want a slightly more neutral/standard tone: kembali ke planetarium is fine.
In casual speech, balik ke planetarium or pergi ke planetarium lagi are also natural, with the small nuance that lagi highlights “again.”

Why do we say kembali ke planetarium with ke? Can kembali stand alone?

Yes, kembali can stand alone, but when you specify the destination you usually add ke:

kembali = “to return / come back (here).”
- Dia sudah kembali. = He/She has already come back.
kembali ke [place] = “to return to [place].”
- Dia kembali ke rumah. = He/She returned home.
- Saya ingin kembali ke planetarium. = I want to return to the planetarium.

Without ke planetarium, kembali would just mean “come back (here)” or “return,” but not say where.
So ke is the normal preposition to show the destination.

Is untuk necessary before melihat, or could I just say …kembali ke planetarium melihat rasi baru?

Untuk often introduces a purpose (“to / in order to”), so:

…kembali ke planetarium untuk melihat rasi baru.
= “…go back to the planetarium to see a new constellation.”

This is the clearest and most standard way to express purpose.

Can you drop untuk?

Sometimes, in more casual speech, people do say things like:
- Dia pergi ke Jakarta cari kerja. (drop untuk)
But in more careful or textbook Indonesian, untuk is normally kept before a verb of purpose.

In this sentence, untuk sounds very natural and is the recommended form, especially for learners.

What exactly does rasi mean? Is rasi baru different from rasi bintang?

rasi means “(star) constellation”, but on its own it’s mostly used in more specialized/astronomy contexts.
Common everyday expression is:

rasi bintang = “constellation” (literally “constellation of stars”).

So:

rasi baru – “a new constellation” (in a context where it’s already clear we’re talking about stars/astronomy, like at a planetarium).
rasi bintang baru – explicitly “a new star constellation,” also perfectly correct.

In your sentence, because you’re at a planetarium and the context is astronomy, rasi baru is natural and understandable.

Why is baru placed after rasi in rasi baru? Does baru always go after the noun?

In Indonesian, most adjectives come after the noun:

rasi baru – new constellation
baju merah – red shirt
mobil cepat – fast car

So rasi baru follows the normal pattern: [noun] + [adjective].

Baru itself has two main uses:

As an adjective = “new”
- rasi baru – a new constellation (new to you / newly discovered / not seen before).
- rumah baru – a new house.
As an adverb of time = “just / only just”
- Saya baru datang. = I just arrived.
- Dia baru makan. = He/She just ate.

When it means “new”, it comes after the noun: rasi baru.
You wouldn’t say baru rasi in this meaning.

Why is there a comma after Andaikan cuaca cerah malam ini? Could I put the clause at the end instead?

Yes, Indonesian conditional sentences can have either order:

Condition first, then main clause (usually with a comma):
- Andaikan cuaca cerah malam ini, saya ingin kembali ke planetarium…
Main clause first, then condition (sometimes without a comma):
- Saya ingin kembali ke planetarium… andaikan cuaca cerah malam ini.

Both are grammatical. The difference is just what you highlight first:

Starting with Andaikan cuaca cerah malam ini emphasizes the condition.
Starting with Saya ingin kembali ke planetarium emphasizes what you want to do, and then adds the condition.

The comma after the first clause is standard punctuation and helps readability.

Why does the sentence use saya and not aku? When should I use saya vs aku?

Both mean “I / me”, but differ in formality:

saya
- Polite, neutral, and safe in almost all situations: speaking to strangers, older people, at work, in formal writing, textbooks.
- Used here because the sentence has a neutral/polite tone.
aku
- More intimate/casual: with friends, family, close peers.
- Often sounds too casual in formal contexts if you don’t already have a close relationship.

Other possibilities (very informal/regional):

gue/gua (Jakarta slang), ane, saya with different styles, etc.

So in a textbook-style sentence like this, saya is the most appropriate and widely acceptable choice.
You could say Aku ingin kembali ke planetarium… with a friend, and it would sound natural in casual conversation.