Learn Hardcore Indonesian: Di ruangan luar angkasa, kami melihat gambar galaksi berwarna biru dan ungu. - In the space room, we see pictures of blue and purple galaxies.

It can sound like a room with an outer-space theme (e.g. in a museum or planetarium).
If you really mean “in outer space”, Indonesians would much more naturally say:
- Di luar angkasa, kami melihat …
  (In outer space, we saw …)

Using ruangan makes many native speakers think of a physical room, not free-floating space.

What’s the difference between ruang, ruangan, and luar angkasa?

ruang
- More abstract or general: space / area / room
- Also used in terms like ruang kelas (classroom), ruang tamu (living room).
ruangan
- Concrete, physical room with walls; more strongly “a room in a building”.
luar angkasa
- Fixed phrase meaning outer space (the cosmos, beyond Earth’s atmosphere).

If you want to say outer space as a place (not a room), use:

di luar angkasa (very common)
di ruang angkasa (less common, more technical/scientific)

Di ruangan luar angkasa most naturally suggests “in an outer-space-themed room” rather than literally drifting in space.

Why does the sentence start with Di ruangan luar angkasa, and why is there a comma after it?

Indonesian often puts time or place information at the beginning of the sentence to set the scene:

Di ruangan luar angkasa, kami melihat …
(In the outer-space room, we saw …)

The structure is:

Place phrase: Di ruangan luar angkasa
Comma
Main clause: kami melihat gambar …

The comma is standard in writing when a location or time phrase comes first, especially if it’s more than one word. In speech, this comma corresponds to a short pause.

You could also say:

Kami melihat gambar galaksi berwarna biru dan ungu di ruangan luar angkasa.

This is also correct; the meaning is the same. The difference is just emphasis and style.

Why is kami used here instead of kita?

Indonesian distinguishes between two kinds of “we”:

kami = we (excluding the person spoken to)
kita = we (including the person spoken to)

In your sentence:

kami melihat gambar galaksi …
→ “we saw a picture of a galaxy (but you were not part of that group).”

Use kami when you talk about your group, not including the listener.
Use kita when the listener is also part of “we”.

If the speaker is telling the listener about something they did together, they would say:

Di ruangan luar angkasa, kita melihat gambar galaksi …

What exactly does melihat mean, and how do I know if it’s past, present, or future?

melihat = to see / to look at (from the root lihat = see).

Indonesian verbs do not change form for tense. melihat can mean:

we see / are seeing
we saw
we will see

The tense is understood from context or from extra time words:

Tadi kami melihat gambar galaksi.
(Earlier, we saw a picture of a galaxy.)
Sekarang kami melihat gambar galaksi.
(Now, we are looking at a picture of a galaxy.)
Nanti kami akan melihat gambar galaksi.
(Later, we will see a picture of a galaxy.)

In your sentence (with no time word), English usually translates it as past (“we saw”) if it’s a narrative context.

How does gambar galaksi work? Why is there no word like “of” (as in “picture of a galaxy”)?

In Indonesian, a common pattern is:

noun 1 + noun 2 = “noun 1 of noun 2” / “noun 2 noun 1”

So:

gambar = picture / image
galaksi = galaxy

gambar galaksi can mean:

picture of a galaxy
galaxy picture / galaxy image

There is no extra word like “of” needed. The second noun (galaksi) describes the first noun (gambar).

Other examples:

gambar kucing = picture of a cat
foto keluarga = family photo
peta dunia = map of the world

Why is there no article like “a” before gambar or galaksi? How do I say “a picture of a galaxy”?

Indonesian has no articles like a / an / the. Context usually tells you whether something is general, singular, or specific.

Your phrase gambar galaksi could be translated as:

a picture of a galaxy
the picture of a galaxy
pictures of galaxies (depending on context)

If you want to make “a (single) picture” explicit, you can add a classifier like sebuah:

Kami melihat sebuah gambar galaksi.
(We saw a picture of a galaxy.)

Similarly:

sebuah buku = a book
sebuah rumah = a house

What does berwarna mean in galaksi berwarna biru dan ungu?

berwarna comes from:

warna = color
prefix ber- (often means “to have / to possess / to be in a state of”)

So berwarna roughly means “having the color (of)”.

galaksi berwarna biru dan ungu = a galaxy that has the colors blue and purple → a blue and purple galaxy.

Common patterns:

baju itu berwarna merah.
(That shirt is red. / That shirt has the color red.)
mobilnya berwarna hitam.
(His/Her car is black.)

You can often drop berwarna in casual speech and just say:

galaksi biru dan ungu
(a blue and purple galaxy)

Why do the colors come after the noun (galaksi berwarna biru dan ungu), not before like in English?

In Indonesian, describing words usually come after the noun:

galaksi biru = blue galaxy
baju merah = red shirt
rumah besar = big house

In your sentence:

galaksi = galaxy
berwarna biru dan ungu = that has the colors blue and purple

So the natural order is:

galaksi berwarna biru dan ungu
galaxy + (having color) blue and purple

If you wanted, you could also say:

galaksi biru dan ungu (more compact)
galaksi yang berwarna biru dan ungu (more formal/explicit, literally “galaxy that is colored blue and purple”)

Is galaksi singular or plural here? How do I say “galaxies” instead of “galaxy”?

galaksi by itself can be singular or plural; the form does not change.

Your sentence:

gambar galaksi berwarna biru dan ungu
could be:
- a picture of a blue and purple galaxy, or
- a picture of blue and purple galaxies
  depending on context.

To make plural clear, you can add a word like:

beberapa = several / some
banyak = many
dua, tiga, empat = two, three, four, etc.

Examples:

gambar beberapa galaksi berwarna biru dan ungu
(a picture of several blue and purple galaxies)
gambar banyak galaksi berwarna biru dan ungu
(a picture of many blue and purple galaxies)