Learn Hardcore Finnish: Yksi suosikkikirjoistani kertoo planeetasta, joka kiertää kaukana olevan tähden ympäri. - One of my favourite books is about a planet that orbits a distant star.

yksi = one
suosikki = favourite (as a noun: “a favourite”)
kirjoista = from (the) books
- kirja = book
- kirja → kirjoi- = plural stem
- -sta = elative case “from / out of”
-ni = my (1st person singular possessive suffix)

So suosikkikirjoistani =
suosikki + kirja + i + sta + ni → from my favourite books / of my favourite books.

Altogether Yksi suosikkikirjoistani literally is “One from my favourite books”, i.e. “One of my favourite books.”

Why is suosikkikirjoistani in the -sta (elative) case? Why not just suosikkikirjani?

Finnish uses the elative (the -sta / -stä case) in the structure:

yksi + [plural elative] = one of ...

Some common patterns:

yksi ystävistäni = one of my friends
yksi parhaista elokuvista = one of the best films
yksi suosikkikirjoistani = one of my favourite books

The elative here has the meaning “from among a group”.
So yksi suosikkikirjoistani literally means “one from among my favourite books.”

If you said yksi suosikkikirjani, it would sound more like “one favourite book of mine” (emphasis on that book being a favourite, less clearly “one of a set of favourites”). The standard way to say “one of my X” is with plural elative: yksi X‑stani.

Why is there no minun in Yksi suosikkikirjoistani? Shouldn’t it be Yksi minun suosikkikirjoistani for “one of my favourite books”?

The possessive is already expressed by the suffix -ni (my) at the end of suosikkikirjoistani.

kirjat = the books
kirjoista = from (the) books
kirjoistani = from my books

In Finnish, you normally use either:

a possessive pronoun (minun, sinun, hänen, meidän, teidän, heidän)
or
a possessive suffix (-ni, -si, -nsa/-nsä, -mme, -nne),

and you need the suffix with kinship terms and many body parts, but for nouns like kirja the pronoun is optional.

So all of these are possible:

Yksi suosikkikirjoistani – perfectly natural, neutral.
Yksi minun suosikkikirjoistani – also correct, but minun adds emphasis: “one of *my favourite books (as opposed to someone else’s)”*.

In everyday use, the version without minun is very common.

Why is planeetasta in the -sta case? Why not just planeetta?

The verb kertoa (“to tell”, “to talk about”) usually takes the elative:

kertoa jostakin = to tell / talk about something
(literally “to tell from something”)

Examples:

Kirja kertoo sodasta. = The book is about the war.
Hän kertoi matkastaan. = He/She talked about his/her trip.
Yksi suosikkikirjoistani kertoo planeetasta. = One of my favourite books is about a planet.

So planeetasta is required by the verb kertoa.
Kirja kertoo planeetta would be ungrammatical; you need planeetasta.

What exactly does joka do in planeetasta, joka kiertää...?

joka is a relative pronoun, like “which/that/who” in English.

It refers back to planeetasta (about a planet).
It starts a relative clause that gives more information about the planet:
- joka kiertää kaukana olevan tähden ympäri
  = which orbits a distant star

Grammatically:

The underlying noun is planeetta (nominative).
In the main clause it appears as planeetasta (elative).
In the relative clause, the pronoun joka stands for that same entity in the nominative, because it is the subject of kiertää:
- (Se planeetta) kiertää ... → joka kiertää ...

If the planet were, say, the object inside the relative clause, a different form of joka (like jota, jonka, jossa etc.) would be used.

Why is there a comma before joka: planeetasta, joka kiertää ...?

In standard written Finnish, a relative clause introduced by joka (or mikä) is normally separated from its head noun by a comma, regardless of whether it’s “restrictive” or “non‑restrictive” as in English.

So you write:

Mies, joka asuu naapurissa, on lääkäri.
Kirja, joka ostin eilen, oli kallis.
planeetasta, joka kiertää kaukana olevan tähden ympäri

Spoken Finnish doesn’t “have commas”, of course; you just pause naturally. But in writing, the comma before joka is the rule, not optional decoration.

What is kaukana olevan grammatically, and what does it literally mean?

kaukana olevan comes from:

kaukana = far away (adverb of place)
oleva = “being” (present active participle of olla “to be”)
kaukana oleva tähti = a star that is far away

Then the whole phrase is put into the genitive:

kaukana olevan tähden = of the star that is far away

So structurally:

kaukana oleva = a participle phrase functioning like an adjective: “far‑away‑being” = “that is far away”
It modifies tähti: kaukana oleva tähti
In this sentence, tähti needs the genitive (tähden), so the modifier also takes genitive agreement: kaukana olevan tähden.

Meaning-wise, kaukana oleva tähti ≈ “a star that is (located) far away.”

Why is it tähden and not tähti or tähteä?

tähden is the genitive singular of tähti (star).

The reason is the postposition ympäri:

ympäri (“around”) normally takes its complement in the genitive:
- talon ympäri = around the house
- maapallon ympäri = around the Earth
- kaukana olevan tähden ympäri = around the distant star

So:

Nominative: tähti
Genitive: tähden → required by ympäri

tähteä would be partitive singular and doesn’t work with ympäri in this structure.

What is the role of ympäri here, and why does it come after tähden?

ympäri is a postposition meaning “around”.

In Finnish, many adpositions come after the noun in the genitive, not before it like English prepositions:

talon ympäri = around the house
pöydän alla = under the table
kaupungin läpi = through the city

So in the sentence:

kaukana olevan tähden ympäri
= around the star that is far away

you must keep:

Noun phrase in genitive: kaukana olevan tähden
Postposition after it: ympäri

You cannot normally move ympäri in front of the noun (*ympäri tähden) in standard Finnish; that would sound wrong.

Could we say kaukainen tähti instead of kaukana oleva tähti? Is there a difference?

Both are grammatical, but they have slightly different nuances:

kaukainen tähti
- literally: “a distant star”
- kaukainen is an adjective meaning “distant, remote”.
- Often describes an inherent or usual characteristic.
kaukana oleva tähti
- literally: “a star that is far away (located far away)”
- focuses more on location: the star is at a far‑away place now.

In many contexts they’re interchangeable, and you could say:

joka kiertää kaukaista tähteä
joka kiertää kaukaisen tähden ympäri

In your original sentence, kaukana olevan tähden ympäri feels very natural, slightly more descriptive/“visual” about the star’s position in space.

Could we say joka kiertää kaukaista tähteä instead of joka kiertää kaukana olevan tähden ympäri?

Yes, that’s possible, but there is a nuance difference:

joka kiertää kaukaista tähteä
- verb kiertää
  - partitive object kaukaista tähteä
- Means roughly “which orbits a distant star”, with the idea of ongoing or repeated activity (partitive object is common with verbs describing continuous processes).
joka kiertää kaukana olevan tähden ympäri
- literally: “which circles around a star that is far away”
- uses ympäri
  - genitive to explicitly express “around”.
- Sounds more spatial/physical: the path goes around the star.

Both are good; the original one is just a bit more explicit about the motion around the star.

How much can we change the word order in the relative clause joka kiertää kaukana olevan tähden ympäri?

Finnish word order is somewhat flexible, but there are constraints:

joka must stay at the beginning of its relative clause (except in marked, poetic styles).
ympäri as a postposition must follow its genitive complement.

So these are fine:

joka kiertää kaukana olevan tähden ympäri (neutral)
joka kaukana olevan tähden ympäri kiertää (possible, a bit marked/emphatic)

These are not acceptable in standard Finnish:

*joka kiertää ympäri kaukana olevan tähden (postposition moved to front)
*joka kiertää tähden kaukana olevan ympäri (breaking the noun phrase apart)

In practice, the original order is the most natural and clear.